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Fagre AC, Soto RA, Magleby R, Cuadera MKQ, Sun A, Cervantes K, Crans SC, Panella NA, Kenney JL, Angelus A, Burkhalter KL, Woell D, Horiuchi K, Biggerstaff BJ, Staples JE, Connelly R, Martin SW, Komar N. Enhancing Eastern Equine Encephalitis Virus Surveillance in New Jersey: Optimized Collection of Culiseta melanura. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2024; 40:92-101. [PMID: 38587266 DOI: 10.2987/23-7148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Eastern equine encephalitis virus (EEEV) causes the most clinically severe neuroinvasive arboviral disease in the United States. The virus is endemic in eastern and Gulf Coast states and the Great Lakes region, causing cases annually. To detect EEEV circulation in its enzootic cycle before the virus infects humans and other mammals, mosquito control agencies in New Jersey have conducted mosquito surveillance using a series of permanent wooden resting box sites since 1975. We conducted 2 field studies, 1 evaluating resting traps and 1 evaluating efficacy of CO2 lures, to optimize collection of Culiseta melanura, the primary enzootic vector of EEEV. Resulting mosquito samples were subjected to molecular analysis to determine EEEV infection rates. Corrugated plastic boxes trapped more bloodfed Cs. melanura than other resting trap types (resting boxes, Centers for Disease Control and Prevention [CDC] resting traps, or fiber pots) and were similar to resting boxes in total number of female Cs. melanura caught. Further, non-baited CDC light traps were more successful in trapping host-seeking Cs. melanura than those baited with dry ice, a CO2 lure. The EEEV RNA was identified in Cs. melanura, Aedes vexans, Anopheles quadrimaculatus, and Uranotaenia sapphirina. Our findings indicate that corrugated plastic boxes and non-CO2 baited traps could improve detection of Cs. melanura. Mosquito control agencies are encouraged to periodically assess their surveillance strategy for EEEV.
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Zubair AS, McAlpine LS, Gobeske KT. Virology, ecology, epidemiology, pathology, and treatment of eastern equine encephalitis. J Neurol Sci 2024; 457:122886. [PMID: 38278094 DOI: 10.1016/j.jns.2024.122886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 12/27/2023] [Accepted: 01/11/2024] [Indexed: 01/28/2024]
Abstract
Eastern equine encephalitis (EEE) was one of the first-recognized neuroinvasive arboviral diseases in North America, and it remains the most lethal. Although EEE is known to have periodic spikes in infection rates, there is increasing evidence that it may be undergoing a change in its prevalence and its public health burden. Numerous factors shape the scope of EEE in humans, and there are important similarities with other emergent viral diseases that have surfaced or strengthened in recent years. Because environmental and ecological conditions that broadly influence the epidemiology of arboviral diseases also are changing, and the frequency, severity, and scope of outbreaks are expected to worsen, an expanded understanding of EEE will have untold importance in coming years. Here we review the factors shaping EEE transmission cycles and the conditions leading to outbreaks in humans from an updated, multidomain perspective. We also provide special consideration of factors shaping the virology, host-vector-environment relationships, and mechanisms of pathology and treatment as a reference for broadening audiences.
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Affiliation(s)
- Adeel S Zubair
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA
| | | | - Kevin T Gobeske
- Department of Neurology, Yale School of Medicine, New Haven, CT, USA.
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Laojun S, Changbunjong T, Sumruayphol S, Chaiphongpachara T. Molecular and morphometric differentiation of secondary filariasis vector Coquillettidia mosquitoes (Diptera: Culicidae) in Thailand. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2023:105452. [PMID: 37257802 DOI: 10.1016/j.meegid.2023.105452] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/13/2023] [Accepted: 05/22/2023] [Indexed: 06/02/2023]
Abstract
Coquillettidia mosquitoes are important nuisance-biting pests and a vector of brugian filariasis in Thailand. However, comprehensive information about these mosquitoes remains unavailable such as molecular and morphometric differences among species. The lack of vector knowledge on Coquillettidia species could affect future disease control. This study aims to investigate differences in molecular variations based on mitochondrial cytochrome oxidase subunit I (COI) gene and wing geometric traits of three Coquillettidia species, namely Cq. crassipes, Cq. nigrosignata, and Cq. ochracea in Thailand. The results of molecular analyses revealed the differences among three Coquillettidia species. The genetic difference measure based on the Kimura two-parameter model among three Coquillettidia species showed low intraspecific distances (0%-3.05%) and large interspecific distances (10.10%-12.41%). The values of intra- and inter-genetic differences of three Coquillettidia species did not overlap which showed the existence of a barcoding gap indicating the efficiency of the identification based on the COI gene. As with molecular analysis, the landmark-based geometric morphometrics approach based on wing shape analysis indicated three distinct species groups which were supported by the high total performance score of cross-validated classification (97.16%). These results provide the first evidence of taxonomic signal based on molecular and wing geometric differences to support species identification and biological variations of Coquillettidia mosquitoes in Thailand for understanding these rare vector mosquitoes in depth and leading to effective further mosquito control.
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Affiliation(s)
- Sedthapong Laojun
- Department of Public Health and Health Promotion, College of Allied Health Sciences, Suan Sunandha Ra-jabhat University, Samut Songkhram 75000, Thailand
| | - Tanasak Changbunjong
- Department of Pre-Clinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand; The Monitoring and Surveillance Center for Zoonotic Diseases in Wildlife and Exotic Animals (MoZWE), Faculty of Veterinary Science, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Suchada Sumruayphol
- Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Tanawat Chaiphongpachara
- Department of Public Health and Health Promotion, College of Allied Health Sciences, Suan Sunandha Ra-jabhat University, Samut Songkhram 75000, Thailand.
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Jian XY, Jiang YT, Wang M, Jia N, Cai T, Xing D, Li CX, Zhao TY, Guo XX, Wu JH. Effects of constant temperature and daily fluctuating temperature on the transovarial transmission and life cycle of Aedes albopictus infected with Zika virus. Front Microbiol 2023; 13:1075362. [PMID: 36687634 PMCID: PMC9845868 DOI: 10.3389/fmicb.2022.1075362] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 12/06/2022] [Indexed: 01/05/2023] Open
Abstract
Introduction Numerous studies on the mosquito life cycle and transmission efficacy were performed under constant temperatures. Mosquito in wild, however, is not exposed to constant temperature but is faced with temperature variation on a daily basis. Methods In the present study, the mosquito life cycle and Zika virus transmission efficiency were conducted at daily fluctuating temperatures and constant temperatures. Aedes albopictus was infected with the Zika virus orally. The oviposition and survival of the infected mosquitoes and hatching rate, the growth cycle of larvae at each stage, and the infection rate (IR) of the progeny mosquitoes were performed at two constant temperatures (23°C and 31°C) and a daily temperature range (DTR, 23-31°C). Results It showed that the biological parameters of mosquitoes under DTR conditions were significantly different from that under constant temperatures. Mosquitoes in DTR survived longer, laid more eggs (mean number: 36.5 vs. 24.2), and had a higher hatching rate (72.3% vs. 46.5%) but a lower pupation rate (37.9% vs. 81.1%) and emergence rate (72.7% vs. 91.7%) than that in the high-temperature group (constant 31°C). When compared to the low-temperature group (constant 23°C), larvae mosquitoes in DTR developed faster (median days: 9 vs. 23.5) and adult mosquitoes carried higher Zika viral RNA load (median log10 RNA copies/μl: 5.28 vs. 3.86). However, the temperature or temperature pattern has no effect on transovarial transmission. Discussion Those results indicated that there are significant differences between mosquito development and reproductive cycles under fluctuating and constant temperature conditions, and fluctuating temperature is more favorable for mosquitos' survival and reproduction. The data would support mapping and predicting the distribution of Aedes mosquitoes in the future and establishing an early warning system for Zika virus epidemics.
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Affiliation(s)
- Xian-yi Jian
- The Key and Characteristic Laboratory of Modern Pathogen Biology, School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China,State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yu-ting Jiang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Miao Wang
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Nan Jia
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Tong Cai
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dan Xing
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Chun-xiao Li
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Tong-yan Zhao
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China,Tong-yan Zhao ✉
| | - Xiao-xia Guo
- State Key Laboratory of Pathogens and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China,Xiao-xia Guo ✉
| | - Jia-hong Wu
- The Key and Characteristic Laboratory of Modern Pathogen Biology, School of Basic Medical Sciences, Guizhou Medical University, Guiyang, China,*Correspondence: Jia-hong Wu ✉
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Eliash N, Suenaga M, Mikheyev AS. Vector-virus interaction affects viral loads and co-occurrence. BMC Biol 2022; 20:284. [PMID: 36527054 PMCID: PMC9758805 DOI: 10.1186/s12915-022-01463-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Accepted: 11/10/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Vector-borne viral diseases threaten human and wildlife worldwide. Vectors are often viewed as a passive syringe injecting the virus. However, to survive, replicate and spread, viruses must manipulate vector biology. While most vector-borne viral research focuses on vectors transmitting a single virus, in reality, vectors often carry diverse viruses. Yet how viruses affect the vectors remains poorly understood. Here, we focused on the varroa mite (Varroa destructor), an emergent parasite that can carry over 20 honey bee viruses, and has been responsible for colony collapses worldwide, as well as changes in global viral populations. Co-evolution of the varroa and the viral community makes it possible to investigate whether viruses affect vector gene expression and whether these interactions affect viral epidemiology. RESULTS Using a large set of available varroa transcriptomes, we identified how abundances of individual viruses affect the vector's transcriptional network. We found no evidence of competition between viruses, but rather that some virus abundances are positively correlated. Furthermore, viruses that are found together interact with the vector's gene co-expression modules in similar ways, suggesting that interactions with the vector affect viral epidemiology. We experimentally validated this observation by silencing candidate genes using RNAi and found that the reduction in varroa gene expression was accompanied by a change in viral load. CONCLUSIONS Combined, the meta-transcriptomic analysis and experimental results shed light on the mechanism by which viruses interact with each other and with their vector to shape the disease course.
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Affiliation(s)
- Nurit Eliash
- grid.18098.380000 0004 1937 0562Shamir Research Institute, University of Haifa, Katzrin, Israel ,grid.250464.10000 0000 9805 2626Okinawa Institute of Science and Technology, 1919-1 Tancha Onna-son, Okinawa, 904-0495 Japan
| | - Miyuki Suenaga
- grid.250464.10000 0000 9805 2626Okinawa Institute of Science and Technology, 1919-1 Tancha Onna-son, Okinawa, 904-0495 Japan
| | - Alexander S. Mikheyev
- grid.250464.10000 0000 9805 2626Okinawa Institute of Science and Technology, 1919-1 Tancha Onna-son, Okinawa, 904-0495 Japan ,grid.1001.00000 0001 2180 7477Australian National University, Canberra, ACT, 2600 Australia
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Vector Competence of Mosquitoes from Germany for Sindbis Virus. Viruses 2022; 14:v14122644. [PMID: 36560650 PMCID: PMC9785343 DOI: 10.3390/v14122644] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Transmission of arthropod-borne viruses (arboviruses) are an emerging global health threat in the last few decades. One important arbovirus family is the Togaviridae, including the species Sindbis virus within the genus Alphavirus. Sindbis virus (SINV) is transmitted by mosquitoes, but available data about the role of different mosquito species as potent vectors for SINV are scarce. Therefore, we investigated seven mosquito species, collected from the field in Germany (Ae. koreicus, Ae. geniculatus, Ae. sticticus, Cx. torrentium, Cx. pipiens biotype pipiens) as well as lab strains (Ae. albopictus, Cx. pipiens biotype molestus, Cx. quinquefasciatus), for their vector competence for SINV. Analysis was performed via salivation assay and saliva was titrated to calculate the amount of infectious virus particles per saliva sample. All Culex and Aedes species were able to transmit SINV. Transmission could be detected at all four investigated temperature profiles (of 18 ± 5 °C, 21 ± 5 °C, 24 ± 5 °C or 27 ± 5 °C), and no temperature dependency could be observed. The concentration of infectious virus particles per saliva sample was in the same range for all species, which may suggest that all investigated mosquito species are able to transmit SINV in Germany.
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Dieme C, Ngo KA, Tyler S, Maffei JG, Zink SD, Dupuis AP, Koetzner CA, Shultis C, Stout J, Payne AF, Backenson PB, Kuo L, Drebot MA, Ciota AT, Kramer LD. Role of Anopheles Mosquitoes in Cache Valley Virus Lineage Displacement, New York, USA. Emerg Infect Dis 2022; 28:303-313. [PMID: 35075998 PMCID: PMC8798675 DOI: 10.3201/eid2802.203810] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Cache Valley virus (CVV) is a mosquitoborne virus that infects livestock and humans. We report results of surveillance for CVV in New York, USA, during 2000–2016; full-genome analysis of selected CVV isolates from sheep, horse, humans, and mosquitoes from New York and Canada; and phenotypic characterization of selected strains. We calculated infection rates by using the maximum-likelihood estimation method by year, region, month, and mosquito species. The highest maximum-likelihood estimations were for Anopheles spp. mosquitoes. Our phylogenetic analysis identified 2 lineages and found evidence of segment reassortment. Furthermore, our data suggest displacement of CVV lineage 1 by lineage 2 in New York and Canada. Finally, we showed increased vector competence of An. quadrimaculatus mosquitoes for lineage 2 strains of CVV compared with lineage 1 strains.
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McGregor BL, Erram D, Alto BW, Lednicky JA, Wisely SM, Burkett-Cadena ND. Vector Competence of Florida Culicoides insignis (Diptera: Ceratopogonidae) for Epizootic Hemorrhagic Disease Virus Serotype-2. Viruses 2021; 13:v13030410. [PMID: 33807536 PMCID: PMC7998304 DOI: 10.3390/v13030410] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/03/2021] [Accepted: 03/04/2021] [Indexed: 01/28/2023] Open
Abstract
Epizootic hemorrhagic disease virus (EHDV; family Reoviridae, genus Orbivirus) is an arthropod-borne virus of ungulates, primarily white-tailed deer in North America. Culicoides sonorensis, the only confirmed North American vector of EHDV, is rarely collected from Florida despite annual virus outbreaks. Culicoides insignis is an abundant species in Florida and is also a confirmed vector of the closely related Bluetongue virus. In this study, oral challenge of C. insignis was performed to determine vector competence for EHDV serotype-2. Field-collected female midges were provided bovine blood spiked with three different titers of EHDV-2 (5.05, 4.00, or 2.94 log10PFUe/mL). After an incubation period of 10 days or after death, bodies and legs were collected. Saliva was collected daily from all females from 3 days post feeding until their death using honey card assays. All samples were tested for EHDV RNA using RT-qPCR. Our results suggest that C. insignis is a weakly competent vector of EHDV-2 that can support a transmissible infection when it ingests a high virus titer (29% of midges had virus positive saliva when infected at 5.05 log10PFUe/mL), but not lower virus titers. Nevertheless, due to the high density of this species, particularly in peninsular Florida, it is likely that C. insignis plays a role in the transmission of EHDV-2.
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Affiliation(s)
- Bethany L. McGregor
- Center for Grain and Animal Health Research, Agricultural Research Service, United States Department of Agriculture, Manhattan, KS 66502, USA
- Correspondence: ; Tel.: +1-785-477-1259
| | - Dinesh Erram
- Florida Medical Entomology Laboratory, Institute of Food and Agricultural Sciences, University of Florida, Vero Beach, FL 32962, USA; (D.E.); (B.W.A.); (N.D.B.-C.)
| | - Barry W. Alto
- Florida Medical Entomology Laboratory, Institute of Food and Agricultural Sciences, University of Florida, Vero Beach, FL 32962, USA; (D.E.); (B.W.A.); (N.D.B.-C.)
| | - John A. Lednicky
- Department of Environmental & Global Health, College of Public Health and Health Professions, University of Florida, Gainesville, FL 32610, USA;
| | - Samantha M. Wisely
- Department of Wildlife Ecology and Conservation, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, USA;
| | - Nathan D. Burkett-Cadena
- Florida Medical Entomology Laboratory, Institute of Food and Agricultural Sciences, University of Florida, Vero Beach, FL 32962, USA; (D.E.); (B.W.A.); (N.D.B.-C.)
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Dieme C, Ciota AT, Kramer LD. Transmission potential of Mayaro virus by Aedes albopictus, and Anopheles quadrimaculatus from the USA. Parasit Vectors 2020; 13:613. [PMID: 33298165 PMCID: PMC7724717 DOI: 10.1186/s13071-020-04478-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 11/05/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mayaro virus (MAYV; Alphavirus, Togaviridae) is an emerging pathogen endemic in South American countries. The increase in intercontinental travel and tourism-based forest excursions has resulted in an increase in MAYV spread, with imported cases observed in Europe and North America. Intriguingly, no local transmission of MAYV has been reported outside South America, despite the presence of potential vectors. METHODS We assessed the vector competence of Aedes albopictus from New York and Anopheles quadrimaculatus for MAYV. RESULTS The results show that Ae. albopictus from New York and An. quadrimaculatus are competent vectors for MAYV. However, Ae. albopictus was more susceptible to infection. Transmission rates increased with time for both species, with rates of 37.16 and 64.44% for Ae. albopictus, and of 25.15 and 48.44% for An. quadrimaculatus, respectively, at 7 and 14 days post-infection. CONCLUSIONS Our results suggest there is a risk of further MAYV spread throughout the Americas and autochthonous transmission in the USA. Preventive measures, such as mosquito surveillance of MAYV, will be essential for early detection.
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Affiliation(s)
- Constentin Dieme
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, USA.
| | - Alexander T Ciota
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, USA
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, New York, USA
| | - Laura D Kramer
- Wadsworth Center, New York State Department of Health, Slingerlands, New York, USA
- Department of Biomedical Sciences, School of Public Health, State University of New York at Albany, Albany, New York, USA
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West RG, Mathias DR, Day JF, Boohene CK, Unnasch TR, Burkett-Cadena ND. Vectorial Capacity of Culiseta melanura (Diptera: Culicidae) Changes Seasonally and Is Related to Epizootic Transmission of Eastern Equine Encephalitis Virus in Central Florida. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00270] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Alto BW, Civana A, Wiggins K, Eastmond B, Shin D. Effect of Oral Infection of Mayaro Virus on Fitness Correlates and Expression of Immune Related Genes in Aedes aegypti. Viruses 2020; 12:E719. [PMID: 32630843 PMCID: PMC7412308 DOI: 10.3390/v12070719] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 06/18/2020] [Accepted: 06/26/2020] [Indexed: 01/01/2023] Open
Abstract
Mayaro virus is a mosquito-borne Alphavirus endemic to forests of tropical South America with a sylvatic cycle involving non-human primates and Haemagogus mosquitoes. Human infection with Mayaro virus causes a febrile illness and long-lasting arthralgia and cases are often associated with exposure to tropical forest habitats. Human movement between tropical forest habitats and urban settings may allow for imported cases and subsequent local transmission by domestic mosquito Aedes aegypti. The relative importance of Ae. aegypti as a vector of Mayaro virus may depend on the pathogenic effects of the virus on fitness correlates, especially those entomological parameters that relate to vectorial capacity. We performed mosquito infection studies and compared adult survival and fecundity of females from Brazilian and Floridian populations of Ae. aegypti following oral ingestion of uninfectious (control) and Mayaro virus infectious blood. Mayaro virus infected and refractory mosquitoes had similar or 30-50% lower fecundity than control (unexposed) mosquitoes, suggesting a reproductive cost to mounting an immune response or phenotypic expression of refractoriness. Survival of adult female mosquitoes and targeted gene expression in the Toll and IMD pathways were not altered by Mayaro virus infection. Adult lifespan and fecundity estimates were independent of measured viral titer in the bodies of mosquitoes. The lack of adverse effects of infection status on female survival suggests that Mayaro virus will not alter vectorial capacity mediated by changes in this parameter.
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Affiliation(s)
- Barry W. Alto
- Florida Medical Entomology Laboratory, University of Florida, 200 9th St. Vero Beach, FL 32962, USA; (A.C.); (K.W.); (B.E.); (D.S.)
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Pereira-dos-Santos T, Roiz D, Lourenço-de-Oliveira R, Paupy C. A Systematic Review: Is Aedes albopictus an Efficient Bridge Vector for Zoonotic Arboviruses? Pathogens 2020; 9:pathogens9040266. [PMID: 32272651 PMCID: PMC7238240 DOI: 10.3390/pathogens9040266] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 04/03/2020] [Accepted: 04/04/2020] [Indexed: 12/17/2022] Open
Abstract
Mosquito-borne arboviruses are increasing due to human disturbances of natural ecosystems and globalization of trade and travel. These anthropic changes may affect mosquito communities by modulating ecological traits that influence the “spill-over” dynamics of zoonotic pathogens, especially at the interface between natural and human environments. Particularly, the global invasion of Aedes albopictus is observed not only across urban and peri-urban settings, but also in newly invaded areas in natural settings. This could foster the interaction of Ae. albopictus with wildlife, including local reservoirs of enzootic arboviruses, with implications for the potential zoonotic transfer of pathogens. To evaluate the potential of Ae. albopictus as a bridge vector of arboviruses between wildlife and humans, we performed a bibliographic search and analysis focusing on three components: (1) The capacity of Ae. albopictus to exploit natural larval breeding sites, (2) the blood-feeding behaviour of Ae. albopictus, and (3) Ae. albopictus’ vector competence for arboviruses. Our analysis confirms the potential of Ae. albopictus as a bridge vector based on its colonization of natural breeding sites in newly invaded areas, its opportunistic feeding behaviour together with the preference for human blood, and the competence to transmit 14 arboviruses.
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Affiliation(s)
- Taissa Pereira-dos-Santos
- MIVEGEC, Univ. Montpellier, IRD, CNRS, 34090 Montpellier, France;
- Correspondence: (T.P.-d.-S.); (C.P.)
| | - David Roiz
- MIVEGEC, Univ. Montpellier, IRD, CNRS, 34090 Montpellier, France;
| | | | - Christophe Paupy
- MIVEGEC, Univ. Montpellier, IRD, CNRS, 34090 Montpellier, France;
- Correspondence: (T.P.-d.-S.); (C.P.)
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Ciota AT, Keyel AC. The Role of Temperature in Transmission of Zoonotic Arboviruses. Viruses 2019; 11:E1013. [PMID: 31683823 PMCID: PMC6893470 DOI: 10.3390/v11111013] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/31/2022] Open
Abstract
We reviewed the literature on the role of temperature in transmission of zoonotic arboviruses. Vector competence is affected by both direct and indirect effects of temperature, and generally increases with increasing temperature, but results may vary by vector species, population, and viral strain. Temperature additionally has a significant influence on life history traits of vectors at both immature and adult life stages, and for important behaviors such as blood-feeding and mating. Similar to vector competence, temperature effects on life history traits can vary by species and population. Vector, host, and viral distributions are all affected by temperature, and are generally expected to change with increased temperatures predicted under climate change. Arboviruses are generally expected to shift poleward and to higher elevations under climate change, yet significant variability on fine geographic scales is likely. Temperature effects are generally unimodal, with increases in abundance up to an optimum, and then decreases at high temperatures. Improved vector distribution information could facilitate future distribution modeling. A wide variety of approaches have been used to model viral distributions, although most research has focused on the West Nile virus. Direct temperature effects are frequently observed, as are indirect effects, such as through droughts, where temperature interacts with rainfall. Thermal biology approaches hold much promise for syntheses across viruses, vectors, and hosts, yet future studies must consider the specificity of interactions and the dynamic nature of evolving biological systems.
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Affiliation(s)
- Alexander T Ciota
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
- Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Rensselaer, NY 12144, USA.
| | - Alexander C Keyel
- Wadsworth Center, New York State Department of Health, Albany, NY 12201, USA.
- Department of Atmospheric and Environmental Sciences, University at Albany, Albany, NY 12222, USA.
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Ciota AT. The role of co-infection and swarm dynamics in arbovirus transmission. Virus Res 2019; 265:88-93. [PMID: 30879977 DOI: 10.1016/j.virusres.2019.03.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 03/11/2019] [Accepted: 03/13/2019] [Indexed: 02/07/2023]
Abstract
Arthropod-borne viruses (arboviruses) are transmitted by hematophagous insects, primarily mosquitoes. The geographic range and prevalence of mosquito-borne viruses and their vectors has dramatically increased over the last 50 years. As a result, the most medically important arboviurses now co-exist in many regions, resulting in an increased frequency of co-infections in hosts and vectors. In addition to concurrent infections with human pathogens, mosquito-only viruses and/or enzootic viruses not associated with human disease are ubiquitous in mosquito populations. Moreover, mosquito-borne viruses are largely RNA viruses that exist within individual hosts as a diverse and dynamic swarm of closely related genotypes. Interactions among co-infecting viruses and genotypes can have profound effects on virulence, fitness and evolution. Here, we review our understanding of how these complex interactions influence transmission of mosquito-borne viruses, focusing on the often-neglected virus interactions in the mosquito vector, and identify gaps in our knowledge that should guide future studies.
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Affiliation(s)
- Alexander T Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY, USA; Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, NY, USA.
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15
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Gaye A, Wang E, Vasilakis N, Guzman H, Diallo D, Talla C, Ba Y, Dia I, Weaver SC, Diallo M. Potential for sylvatic and urban Aedes mosquitoes from Senegal to transmit the new emerging dengue serotypes 1, 3 and 4 in West Africa. PLoS Negl Trop Dis 2019; 13:e0007043. [PMID: 30759080 PMCID: PMC6373929 DOI: 10.1371/journal.pntd.0007043] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 12/02/2018] [Indexed: 01/19/2023] Open
Abstract
Dengue fever (DEN) is the most common arboviral disease in the world and dengue virus (DENV) causes 390 million annual infections around the world, of which 240 million are inapparent and 96 million are symptomatic. During the past decade a changing epidemiological pattern has been observed in Africa, with DEN outbreaks reported in all regions. In Senegal, all DENV serotypes have been reported. These important changes in the epidemiological profile of DEN are occurring in a context where there is no qualified vaccine against DEN. Further there is significant gap of knowledge on the vector bionomics and transmission dynamics in the African region to effectively prevent and control epidemics. Except for DENV-2, few studies have been performed with serotypes 1, 3, and 4, so this study was undertaken to fill out this gap. We assessed the vector competence of Aedes (Diceromyia) furcifer, Ae. (Diceromyia) taylori, Ae. (Stegomyia) luteocephalus, sylvatic and urban Ae. (Stegomyia) aegypti populations from Senegal for DENV-1, DENV-3 and DENV-4 using experimental oral infection. Whole bodies and wings/legs were tested for DENV presence by cell culture assays and saliva samples were tested by real time RT-PCR to estimate infection, disseminated infection and transmission rates. Our results revealed a low capacity of sylvatic and urban Aedes mosquitoes from Senegal to transmit DENV-1, DENV-3 and DENV-4 and an impact of infection on their mortality. The highest potential transmission rate was 20% despite the high susceptibility and disseminated infection rates up to 93.7% for the 3 Ae. aegypti populations tested, and 84.6% for the sylvatic vectors Ae. furcifer, Ae. taylori and Ae. luteocephalus.
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Affiliation(s)
- Alioune Gaye
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Senegal
| | - Eryu Wang
- Institute for Human Infections and Immunity, Center for Tropical Diseases and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas
| | - Nikos Vasilakis
- Institute for Human Infections and Immunity, Center for Tropical Diseases and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas
- Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Hilda Guzman
- Department of Pathology and Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Diawo Diallo
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Senegal
| | - Cheikh Talla
- Epidemiological Infectious Disease Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Yamar Ba
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Senegal
| | - Ibrahima Dia
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Senegal
| | - Scott C. Weaver
- Institute for Human Infections and Immunity, Center for Tropical Diseases and Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas
| | - Mawlouth Diallo
- Unité d’Entomologie Médicale, Institut Pasteur de Dakar, Dakar, Senegal
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da Silveira ID, Petersen MT, Sylvestre G, Garcia GA, David MR, Pavan MG, Maciel-de-Freitas R. Zika Virus Infection Produces a Reduction on Aedes aegypti Lifespan but No Effects on Mosquito Fecundity and Oviposition Success. Front Microbiol 2018; 9:3011. [PMID: 30619118 PMCID: PMC6305470 DOI: 10.3389/fmicb.2018.03011] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/21/2018] [Indexed: 11/13/2022] Open
Abstract
A Zika virus (ZIKV) pandemic started soon after the first autochthonous cases in Latin America. Although Aedes aegypti is pointed as the primary vector in Latin America, little is known about the fitness cost due to ZIKV infection. We investigated the effects of ZIKV infection on the life-history traits of Ae. aegypti females collected in three districts of Rio de Janeiro, Brazil (Barra, Deodoro, and Porto), equidistant ~25 km each other. Aedes aegypti mosquitoes were classified into infected (a single oral challenge with ZIKV) and superinfected (two ZIKV-infected blood meals spaced by 7 days each other). ZIKV infection reduced Ae. aegypti survival in two of the three populations tested, and superinfection produced a sharper increase in mortality in one of those populations. We hypothesized higher mortality with the presence of more ZIKV copies in Ae. aegypti females from Porto. The number of eggs laid per clutch was statistically similar between vector populations and infected and uninfected mosquitoes. Infection by ZIKV not affected female oviposition success. ZIKV infection impacted Ae. aegypti vectorial capacity by reducing its lifespan, although female fecundity remained unaltered. The outcome of these findings to disease transmission intensity still needs further evaluation.
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Affiliation(s)
- Isabella Dias da Silveira
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Martha Thieme Petersen
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Gabriel Sylvestre
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Gabriela Azambuja Garcia
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Mariana Rocha David
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil
| | - Márcio Galvão Pavan
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rafael Maciel-de-Freitas
- Laboratório de Mosquitos Transmissores de Hematozoários, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, Brazil.,Instituto Nacional de Ciência e Tecnologia em Entomologia Molecular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Blore K, Beier JC, Xue RD. Impact of Three Species of Aquatic Plants on Anopheles quadrimaculatus and its Effect on the Efficacy of Boric Acid Sugar Baits. JOURNAL OF THE AMERICAN MOSQUITO CONTROL ASSOCIATION 2018; 34:50-52. [PMID: 31442109 DOI: 10.2987/17-6660.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The purpose of this study was to investigate the sugar-feeding behavior of Anopheles quadrimaculatus by measuring the impact of different aquatic plants on its survival. At the same time, the potential use of boric acid in toxic sugar bait (TSB) applications to the leaves of these plants was also evaluated. Mean survival rates of mosquitoes after 120 h feeding on 3 common aquatic plant species-Thalia geniculata, Pontederia cordata, and Limnobium spongia-were 10.55%, 1.86%, and 6.21%, respectively. No significant difference in mortality between mosquitoes feeding on separate plant species was detected (P = 0.05). The TSB efficacy was evaluated by leaf dip bioassay to compare 24-h mortality of mosquitoes feeding on leaves treated with TSB formulation (1% boric acid, 10% sucrose) and leaves dipped in 10% sucrose. Mortality was significantly higher for TSB-treated leaves for T. geniculata (t = 12.5, df = 8, P < 0.0001) and P. cordata (t = 5.42, df = 8, P = 0.0006) than for L. spongia (t = 1.4003, df = 8, P = 0.199). One-way ANOVA analysis showed no significant difference in efficacy between TSB-treated leaves of the 3 plants.
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18
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Kramer LD, Ciota AT. Dissecting vectorial capacity for mosquito-borne viruses. Curr Opin Virol 2015; 15:112-8. [PMID: 26569343 DOI: 10.1016/j.coviro.2015.10.003] [Citation(s) in RCA: 131] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 10/02/2015] [Accepted: 10/19/2015] [Indexed: 01/01/2023]
Abstract
The inter-relationship between mosquitoes and the viruses they transmit is complex. While previously understood barriers to infection and transmission remain valid, additional factors have been uncovered that suggest an 'arms race' between mosquito and virus. These include the mosquito microbiota and interplay between mosquito and viral genetics. Following an infectious blood meal, the mosquito mounts an immune and transcriptional response, leading to altered expression of multiple genes. These complex interactions, specific to vector and virus genotypes, combine with external influences, particularly temperature, to determine vector competence. The mosquito's response to the infecting agent may have consequences in terms of longevity, feeding behavior and/or fecundity. These factors, together with population density and the frequency of host contact determine vectorial capacity.
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Affiliation(s)
- Laura D Kramer
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, NY, USA.
| | - Alexander T Ciota
- Wadsworth Center, New York State Department of Health, and School of Public Health, State University of New York at Albany, Albany, NY, USA.
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19
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Molaei G, Armstrong PM, Graham AC, Kramer LD, Andreadis TG. Insights into the recent emergence and expansion of eastern equine encephalitis virus in a new focus in the Northern New England USA. Parasit Vectors 2015; 8:516. [PMID: 26453283 PMCID: PMC4600208 DOI: 10.1186/s13071-015-1145-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/03/2015] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Eastern equine encephalomyelitis virus (EEEV) causes a highly pathogenic zoonosis that circulates in an enzootic cycle involving the ornithophagic mosquito, Culiseta melanura, and wild passerine birds in freshwater hardwood swamps in the northeastern U.S. Epidemic/epizootic transmission to humans/equines typically occurs towards the end of the transmission season and is generally assumed to be mediated by locally abundant and contiguous mammalophagic "bridge vector" mosquitoes. METHODS Engorged mosquitoes were collected using CDC light, resting box, and gravid traps during epidemic transmission of EEEV in 2012 in Addison and Rutland counties, Vermont. Mosquitoes were identified to species and blood meal analysis performed by sequencing mitochondrial cytochrome b gene polymerase chain reaction products. Infection status with EEEV in mosquitoes was determined using cell culture and RT-PCR assays, and all viral isolates were sequenced and compared to other EEEV strains by phylogenetic analysis. RESULTS The host choices of 574 engorged mosquitoes were as follows: Cs. melanura (n = 331, 94.3 % avian-derived, 5.7 % mammalian-derived); Anopheles quadrimaculatus (n = 164, 3.0 % avian, 97.0 % mammalian); An. punctipennis (n = 56, 7.2 % avian, 92.8 % mammalian), Aedes vexans (n = 9, 22.2 % avian, 77.8 % mammalian); Culex pipiens s.l. n = 6, 100 % avian); Coquillettidia perturbans (n = 4, 25.0 % avian, 75.0 % mammalian); and Cs. morsitans (n = 4, 100 % avian). A seasonal shift in blood feeding by Cs. melanura from Green Heron towards other avian species was observed. EEEV was successfully isolated from blood-fed Cs. melanura and analyzed by phylogenetic analysis. Vermont strains from 2012 clustered with viral strains previously isolated in Virginia yet were genetically distinct from an earlier EEEV isolate from Vermont during 2011. CONCLUSIONS Culiseta melanura acquired blood meals primarily from birds and focused feeding activity on several competent species capable of supporting EEEV transmission. Culiseta melanura also occasionally obtained blood meals from mammalian hosts including humans. This mosquito species serves as the primary vector of EEEV among wild bird species, but also is capable of occasionally contributing to epidemic/epizootic transmission of EEEV to humans/equines. Other mosquito species including Cq. perturbans that feed more opportunistically on both avian and mammalian hosts may be important in epidemic/epizootic transmission under certain conditions. Phylogenetic analyses suggest that EEEV was independently introduced into Vermont on at least two separate occasions.
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Affiliation(s)
- Goudarz Molaei
- Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
| | - Philip M Armstrong
- Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
| | - Alan C Graham
- Vermont Agency of Agriculture, 322 Industrial Lane, Barre, VT, 05641, USA.
| | - Laura D Kramer
- Wadsworth Center, New York State Department of Health, 5668 State Farm Rd, Slingerlands, NY, 12159, USA.
| | - Theodore G Andreadis
- Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
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20
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Alto BW, Richards SL, Anderson SL, Lord CC. Survival of West Nile virus-challenged Southern house mosquitoes, Culex pipiens quinquefasciatus, in relation to environmental temperatures. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2014; 39:123-33. [PMID: 24820564 PMCID: PMC4874492 DOI: 10.1111/j.1948-7134.2014.12078.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 02/17/2014] [Indexed: 05/25/2023]
Abstract
We investigated the effect of West Nile virus (WNV) infection on survival in two colonies of Culex pipiens quinquefasciatus Say (Diptera: Culicidae) originating from Vero Beach and Gainesville, FL. Mosquitoes were fed West Nile virus-infected blood and checked daily for survival. Exposure to WNV decreased survival among Cx. p. quinquefasciatus from Gainesville relative to unexposed individuals at 31° C. In contrast, exposure to WNV enhanced survival among Cx. p. quinquefasciatus from Vero Beach relative to unexposed individuals at 27° C. These results may suggest that exposure to WNV and associated infection could increase or decrease components of fitness, dependent on environmental temperature and intraspecific variation in Cx. p. quinquefasciatus. The relationship between lifespan (time of death in days) and WNV titer differed in the colonies at 31° C and 27° C, suggesting that intraspecific species variation in response to temperature impacts interactions with WNV. While further work is needed to determine if similar effects occur under field conditions, this suggests intraspecific variation in vector competence for WNV and adult survival of Cx. p. quinquefasciatus, both aspects of vectorial capacity.
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Affiliation(s)
- Barry W Alto
- Florida Medical Entomology Laboratory, University of Florida, 200 9th St. S.E. Vero Beach, FL 32962, U.S.A..
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21
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Costanzo KS, Muturi EJ, Montgomery AV, Alto BW. Effect of oral infection of La Crosse virus on survival and fecundity of native Ochlerotatus triseriatus and invasive Stegomyia albopicta. MEDICAL AND VETERINARY ENTOMOLOGY 2014; 28:77-84. [PMID: 23781898 DOI: 10.1111/mve.12018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 01/11/2013] [Accepted: 02/18/2013] [Indexed: 06/02/2023]
Abstract
Arboviruses can have benign, deleterious, or beneficial effects on the vector. We tested the hypothesis that oral infection with La Crosse virus (LACV) will have little to no effect on mosquito longevity and fecundity, a prediction of low virulence selected in a system with frequent vertical transmission. We tested the effects of infection in native Ochlerotatus triseriatus Say and invasive Stegomyia albopicta Skuse (Diptera: Culicidae). We artificially fed adult female mosquitoes of each species with either LACV-infected or uninfected bovine blood and determined adult longevity and fecundity. For females fed LACV-infected blood, bodies and legs, respectively, were separately homogenized and assayed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) to determine the LACV infection and dissemination rates. Ochlerotatus triseriatus had a higher infection and dissemination rate than St. albopicta. For both species, female size had no effect on infection status. Infection status also had no effect on longevity or fecundity for both species. We suggest that the high frequency of vertical transmission may have selected for strains of the virus with low virulence in two vectors, in spite of their different evolutionary histories with the virus.
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Affiliation(s)
- K S Costanzo
- Department of Biology, Canisius College, Buffalo, NY, U.S.A
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Vector-virus interactions and transmission dynamics of West Nile virus. Viruses 2013; 5:3021-47. [PMID: 24351794 PMCID: PMC3967159 DOI: 10.3390/v5123021] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Revised: 11/04/2013] [Accepted: 11/06/2013] [Indexed: 12/17/2022] Open
Abstract
West Nile virus (WNV; Flavivirus; Flaviviridae) is the cause of the most widespread arthropod-borne viral disease in the world and the largest outbreak of neuroinvasive disease ever observed. Mosquito-borne outbreaks are influenced by intrinsic (e.g., vector and viral genetics, vector and host competence, vector life-history traits) and extrinsic (e.g., temperature, rainfall, human land use) factors that affect virus activity and mosquito biology in complex ways. The concept of vectorial capacity integrates these factors to address interactions of the virus with the arthropod host, leading to a clearer understanding of their complex interrelationships, how they affect transmission of vector-borne disease, and how they impact human health. Vertebrate factors including host competence, population dynamics, and immune status also affect transmission dynamics. The complexity of these interactions are further exacerbated by the fact that not only can divergent hosts differentially alter the virus, but the virus also can affect both vertebrate and invertebrate hosts in ways that significantly alter patterns of virus transmission. This chapter concentrates on selected components of the virus-vector-vertebrate interrelationship, focusing specifically on how interactions between vector, virus, and environment shape the patterns and intensity of WNV transmission.
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Ocampo CB, Caicedo PA, Jaramillo G, Ursic Bedoya R, Baron O, Serrato IM, Cooper DM, Lowenberger C. Differential expression of apoptosis related genes in selected strains of Aedes aegypti with different susceptibilities to dengue virus. PLoS One 2013; 8:e61187. [PMID: 23593426 PMCID: PMC3622604 DOI: 10.1371/journal.pone.0061187] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 03/07/2013] [Indexed: 01/06/2023] Open
Abstract
Aedes aegypti is the principal vector of Dengue viruses worldwide. We identified field collected insects with differential susceptibility to Dengue-2 virus (DENv-2) and used isofemale selection to establish susceptible and refractory strains based on midgut infection barriers. Previous experiments had identified higher expression of apoptosis-related genes in the refractory strain. To identify potential molecular mechanisms associated with DENv susceptibility, we evaluated the differential expression of Caspase-16, Aedronc, Aedredd, Inhibitor of apoptosis (AeIAP1) and one member of the RNAi pathway, Argonaute-2 in the midguts and fat body tissues of the selected strains at specific times post blood feeding or infection with DENv-2. In the refractory strain there was significantly increased expression of caspases in midgut and fatbody tissues in the presence of DENv-2, compared to exposure to blood alone, and significantly higher caspase expression in the refractory strain compared with the susceptible strain at timepoints when DENv was establishing in these tissues. We used RNAi to knockdown gene expression; knockdown of AeIAP1 was lethal to the insects. In the refractory strain, knockdown of the pro-apoptotic gene Aedronc increased the susceptibility of refractory insects to DENv-2 from 53% to 78% suggesting a contributing role of this gene in the innate immune response of the refractory strain.
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Affiliation(s)
- Clara B. Ocampo
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
| | - Paola A. Caicedo
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
| | - Gloria Jaramillo
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
| | - Raul Ursic Bedoya
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- Tekmira Pharmaceuticals Corporation, Burnaby, British Columbia, Canada
| | - Olga Baron
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
- Université Nice Sophia Antipolis, Nice, France
| | - Idalba M. Serrato
- Centro Internacional de Entrenamiento e Investigaciones Médicas (CIDEIM), Cali, Colombia
| | - Dawn M. Cooper
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Carl Lowenberger
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
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Effects of Bartonella spp. on flea feeding and reproductive performance. Appl Environ Microbiol 2013; 79:3438-43. [PMID: 23542614 DOI: 10.1128/aem.00442-13] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Numerous pathogens are transmitted from one host to another by hematophagous insect vectors. The interactions between a vector-borne organism and its vector vary in many ways, most of which are yet to be explored and identified. These interactions may play a role in the dynamics of the infection cycle. One way to evaluate these interactions is by studying the effects of the tested organism on the vector. In this study, we tested the effects of infection with Bartonella species on fitness-related variables of fleas by using Bartonella sp. strain OE 1-1, Xenopsylla ramesis fleas, and Meriones crassus jirds as a model system. Feeding parameters, including blood meal size and metabolic rate during digestion, as well as reproductive parameters, including fecundity, fertility, and life span, were compared between fleas experimentally infected with Bartonella and uninfected fleas. In addition, the developmental time, sex ratio, and body size of F1 offspring fleas were compared between the two groups. Most tested parameters did not differ between infected and uninfected fleas. However, F1 males produced by Bartonella-positive females were significantly smaller than F1 males produced by Bartonella-negative female fleas. The findings in this study suggest that bartonellae are well adapted to their flea vectors, and by minimally affecting their fitness they have evolved to better spread themselves in the natural environment.
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Ciota AT, Ehrbar DJ, Matacchiero AC, Van Slyke GA, Kramer LD. The evolution of virulence of West Nile virus in a mosquito vector: implications for arbovirus adaptation and evolution. BMC Evol Biol 2013; 13:71. [PMID: 23514328 PMCID: PMC3626576 DOI: 10.1186/1471-2148-13-71] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 03/11/2013] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Virulence is often coupled with replicative fitness of viruses in vertebrate systems, yet the relationship between virulence and fitness of arthropod-borne viruses (arboviruses) in invertebrates has not been evaluated. Although the interactions between vector-borne pathogens and their invertebrate hosts have been characterized as being largely benign, some costs of arbovirus exposure have been identified for mosquitoes. The extent to which these costs may be strain-specific and the subsequent consequences of these interactions on vector and virus evolution has not been adequately explored. RESULTS Using West Nile virus (WNV) and Culex pipiens mosquitoes, we tested the hypothesis that intrahost fitness is correlated with virulence in mosquitoes by evaluating life history traits following exposure to either non-infectious bloodmeals or bloodmeals containing wildtype (WNV WT) or the high fitness, mosquito-adapted strain, WNV MP20 derived from WNV WT. Our results demonstrate strain-specific effects on mosquito survival, fecundity, and blood feeding behavior. Specifically, both resistance to and infection with WNV MP20, but not WNV WT, decreased survival of Cx. pipiens and altered fecundity and bloodfeeding such that early egg output was enhanced at a later cost. CONCLUSIONS As predicted by the trade-off hypothesis of virulence, costs of infection with WNV MP20 in terms of survival were directly correlated to viral load, yet resistance to infection with this virulent strain was equally costly. Taken together, these results demonstrate that WNV MP20 infection decreases the transmission potential of Cx. pipiens populations despite the increased intrahost fitness of this strain, indicating that a virulence-transmission trade-off in invertebrates could contribute significantly to the adaptive and evolutionary constraint of arboviruses.
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Affiliation(s)
- Alexander T Ciota
- Wadsworth Center, Arbovirus laboratory, New York State Department of Health, 5668 State Farm Road, Slingerlands, NY 12159, USA.
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Tabachnick WJ. Nature, nurture and evolution of intra-species variation in mosquito arbovirus transmission competence. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2013; 10:249-77. [PMID: 23343982 PMCID: PMC3564141 DOI: 10.3390/ijerph10010249] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 12/29/2012] [Accepted: 01/09/2013] [Indexed: 01/14/2023]
Abstract
Mosquitoes vary in their competence or ability to transmit arthropod-borne viruses (arboviruses). Many arboviruses cause disease in humans and animals. Identifying the environmental and genetic causes of variation in mosquito competence for arboviruses is one of the great challenges in public health. Progress identifying genetic (nature) and environmental (nurture) factors influencing mosquito competence for arboviruses is reviewed. There is great complexity in the various traits that comprise mosquito competence. The complex interactions between environmental and genetic factors controlling these traits and the factors shaping variation in Nature are largely unknown. The norms of reaction of specific genes influencing competence, their distributions in natural populations and the effects of genetic polymorphism on phenotypic variation need to be determined. Mechanisms influencing competence are not likely due to natural selection because of the direct effects of the arbovirus on mosquito fitness. More likely the traits for mosquito competence for arboviruses are the effects of adaptations for other functions of these competence mechanisms. Determining these other functions is essential to understand the evolution and distributions of competence for arboviruses. This information is needed to assess risk from mosquito-borne disease, predict new mosquito-arbovirus systems, and provide novel strategies to mitigate mosquito-borne arbovirus transmission.
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Affiliation(s)
- Walter J Tabachnick
- Florida Medical Entomology Laboratory, University of Florida, IFAS, 200 9th St. SE, Vero Beach, FL 32962, USA.
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Hernández-Jover M, Roche S, Ward MP. The human and animal health impacts of introduction and spread of an exotic strain of West Nile virus in Australia. Prev Vet Med 2012; 109:186-204. [PMID: 23098914 DOI: 10.1016/j.prevetmed.2012.09.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 09/07/2012] [Accepted: 09/23/2012] [Indexed: 10/27/2022]
Abstract
Vector-borne diseases can have substantial impacts on human and animal health, including major epidemics. West Nile virus (WNV) is of particular international importance due to its recent emergence and impact in the Western Hemisphere. Despite the presence of a sub-type of WNV (Kunjin virus, KUN) in Australia, a potential ecological niche could be occupied by an exotic strain of WNV of the North American type. This study assesses the probability an exotic strain of WNV enters Australia via an infected mosquito in an aircraft from the United States (U.S.) landing at Sydney airport, the probability it spreads to susceptible species and the impact of the resulting outbreak on human and animal health. A release, exposure and consequence assessment were conducted using expert opinion and scientific literature to parameterise the inputs for the models (OIE, 2009). Following establishment of WNV in Australia, the spatio-temporal spread of WNV was predicted over a six year period based on the Australian human and equine populations at-risk, the known distribution of other mosquito-borne flaviviruses in Australia, climatic factors, and the spread of WNV in the U.S. following it's incursion in New York City in 1999. The impact of this spread was measured as a multiplier of human and equine demographics using the U.S. incidence and case fatality rates as a reference. For an 8 month period from September to April (considering seasonal impact on mosquito activity during the coldest months in Australia and the U.S.), and assuming WNV is endemic in the U.S., the median probability an infected mosquito is introduced is 0.17, and the median number of infected mosquitoes introduced is predicted to be zero, with a 95th percentile range of one. The overall probability of a WNV outbreak (WNV released into Australia, susceptible hosts exposed and the virus spread) occurring in the human and the horse population during this time period is estimated to be 7.0×10(-6) and 3.9×10(-6), respectively. These values are largely influenced by the presence of mosquitoes in aircrafts and whether the introduced infected mosquito contacts wild birds. Results of this study suggest there is a low risk of introduction and spread of an exotic strain of WNV from the U.S via aircraft, and provides an insight into the magnitude and impact of the spread among human and horse populations. The generic framework presented could be applied to assess the potential introduction of other mosquito-borne diseases (which involve a wild bird transmission cycle) via international aircraft movements.
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Ciota AT, Styer LM, Meola MA, Kramer LD. The costs of infection and resistance as determinants of West Nile virus susceptibility in Culex mosquitoes. BMC Ecol 2011; 11:23. [PMID: 21975028 PMCID: PMC3215953 DOI: 10.1186/1472-6785-11-23] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 10/05/2011] [Indexed: 12/03/2022] Open
Abstract
Background Understanding the phenotypic consequences of interactions between arthropod-borne viruses (arboviruses) and their mosquito hosts has direct implications for predicting the evolution of these relationships and the potential for changes in epidemiological patterns. Although arboviruses are generally not highly pathogenic to mosquitoes, pathology has at times been noted. Here, in order to evaluate the potential costs of West Nile virus (WNV) infection and resistance in a primary WNV vector, and to assess the extent to which virus-vector relationships are species-specific, we performed fitness studies with and without WNV exposure using a highly susceptible Culex pipiens mosquito colony. Specifically, we measured and compared survival, fecundity, and feeding rates in bloodfed mosquitoes that were (i) infected following WNV exposure (susceptible), (ii) uninfected following WNV exposure (resistant), or (iii) unexposed. Results In contrast to our previous findings with a relatively resistant Cx. tarsalis colony, WNV infection did not alter fecundity or blood-feeding behaviour of Cx. pipiens, yet results do indicate that resistance to infection is associated with a fitness cost in terms of mosquito survival. Conclusions The identification of species-specific differences provides an evolutionary explanation for variability in vector susceptibility to arboviruses and suggests that understanding the costs of infection and resistance are important factors in determining the potential competence of vector populations for arboviruses.
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Goethert HK, Telford SR. Differential mortality of dog tick vectors due to infection by diverse Francisella tularensis tularensis genotypes. Vector Borne Zoonotic Dis 2011; 11:1263-8. [PMID: 21612530 PMCID: PMC3162643 DOI: 10.1089/vbz.2010.0237] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The factors involved in the long-term perpetuation of Francisella tularensis tularensis in nature are poorly understood. Martha's Vineyard, Massachusetts, has become a site of sustained transmission of Type A tularemia, with nearly 100 human cases reported from 2000 to 2010. We have identified a stable focus of F. tularensis transmission there, where the annual prevalence in host-seeking Dermacentor variabilis is about 3%, suggesting that this tick perpetuates the agent. However, laboratory studies have shown that infection with F. tularensis has a profound negative effect on dog tick mortality, presenting a paradox: how can a vector perpetuate an agent that negatively affects its fitness? It may be that experimental infection does not mimic that of natural transmission. Accordingly, we examined the effects that F. tularensis has on the longevity of field-derived ticks. Of 63 PCR-positive ticks collected in early summer, 89% were dead by December compared to 48% of 214 uninfected ticks collected at the same time and site. However, the quantum of F. tularensis DNA within each tick was not correlated with increased mortality. Instead, ticks with an uncommon genotype were more likely to die early than those with the common genotype. We conclude that the interaction between F. tularensis and its vector is complex and certain bacterial genotypes appear to be better adapted to their arthropod host.
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Affiliation(s)
- Heidi K Goethert
- Division of Infectious Diseases, Tufts Cummings School of Veterinary Medicine, North Grafton, Massachusetts 01536, USA
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Rochlin I, Turbow D, Gomez F, Ninivaggi DV, Campbell SR. Predictive mapping of human risk for West Nile virus (WNV) based on environmental and socioeconomic factors. PLoS One 2011; 6:e23280. [PMID: 21853103 PMCID: PMC3154328 DOI: 10.1371/journal.pone.0023280] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 07/11/2011] [Indexed: 11/18/2022] Open
Abstract
A West Nile virus (WNV) human risk map was developed for Suffolk County, New York utilizing a case-control approach to explore the association between the risk of vector-borne WNV and habitat, landscape, virus activity, and socioeconomic variables derived from publically available datasets. Results of logistic regression modeling for the time period between 2000 and 2004 revealed that higher proportion of population with college education, increased habitat fragmentation, and proximity to WNV positive mosquito pools were strongly associated with WNV human risk. Similar to previous investigations from north-central US, this study identified middle class suburban neighborhoods as the areas with the highest WNV human risk. These results contrast with similar studies from the southern and western US, where the highest WNV risk was associated with low income areas. This discrepancy may be due to regional differences in vector ecology, urban environment, or human behavior. Geographic Information Systems (GIS) analytical tools were used to integrate the risk factors in the 2000–2004 logistic regression model generating WNV human risk map. In 2005–2010, 41 out of 46 (89%) of WNV human cases occurred either inside of (30 cases) or in close proximity (11 cases) to the WNV high risk areas predicted by the 2000–2004 model. The novel approach employed by this study may be implemented by other municipal, local, or state public health agencies to improve geographic risk estimates for vector-borne diseases based on a small number of acute human cases.
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Affiliation(s)
- Ilia Rochlin
- Suffolk County Vector Control, Yaphank, New York, United States of America.
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Brown CR, O'Brien VA. Are Wild Birds Important in the Transport of Arthropod-borne Viruses? ACTA ACUST UNITED AC 2011. [DOI: 10.1525/om.2011.71.1.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Deardorff ER, Weaver SC. Vector competence of Culex (Melanoconion) taeniopus for equine-virulent subtype IE strains of Venezuelan equine encephalitis virus. Am J Trop Med Hyg 2010; 82:1047-52. [PMID: 20519599 DOI: 10.4269/ajtmh.2010.09-0556] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The mosquito Culex (Melanoconion) taeniopus is a proven vector of enzootic Venezuelan equine encephalitis virus (VEEV) subtype IE in Central America. It has been shown to be highly susceptible to infection by this subtype, and conversely to be highly refractory to infection by other VEEV subtypes. During the 1990s in southern coastal Mexico, two VEE epizootics in horses were attributed to subtype IE VEEV. These outbreaks were associated with VEEV strains with an altered infection phenotype for the epizootic mosquito vector, Aedes (Ochlerotatus) taeniorhynchus. To determine the infectivity for the enzootic vector, Culex taeniopus, mosquitoes from a recently established colony were orally exposed to VEEV strains from the outbreak. The equine-virulent strains exhibited high infectivity and transmission potential comparable to a traditional enzootic subtype IE VEEV strain. Thus, subtype IE VEEV strains in Chiapas are able to efficiently infect enzootic and epizootic vectors and cause morbidity and mortality in horses.
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Affiliation(s)
- Eleanor R Deardorff
- Center for Tropical Diseases and Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA.
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Brown CR, Moore AT, Young GR, Komar N. Persistence of Buggy Creek virus (Togaviridae, Alphavirus) for two years in unfed swallow bugs (Hemiptera: Cimicidae: Oeciacus vicarius). JOURNAL OF MEDICAL ENTOMOLOGY 2010; 47:436-41. [PMID: 20496591 PMCID: PMC2903633 DOI: 10.1603/me09288] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Alphaviruses (Togaviridae) have rarely been found to persist for long in the adult insects that serve as their vectors. The ectoparasitic swallow bug (Hemiptera: Cimicidae: Oeciacus vicarius Horvath), the vector for Buggy Creek virus (BCRV; Togaviridae, Alphavirus), lives year-round in the mud nests of its host, the cliff swallow (Petrochelidon pyrrhonota Vieillot). We measured the prevalence of BCRV in swallow bugs at sites with cliff swallows present and at the same sites after cliff swallows had been absent for 2 yr. We collected bugs directly from cliff swallow nests in the field and screened bug pools with BCRV-specific real-time-polymerase chain reaction (RT-PCR) and plaque assay. At two colony sites last occupied by birds 2 yr earlier, we found 12.5 and 55.6% of bug pools positive for BCRV RNA by RT-PCR. Infection rates (per 1,000 bugs) for these sites were 1.32 and 7.39. RNA prevalence in the unfed bugs was not significantly different from that in fed bugs 2 yr earlier at the same sites. The RNA-positive samples from unfed bugs failed to yield cytopathic BCRV by Vero-cell plaque assay. However, viral RNA concentrations did not differ between unfed bugs and bugs at active sites, and over 84% of positive bug pools were cytopathic to Vero cells 4-5 wk later, after cliff swallows moved into one of the colony sites. These data demonstrate the persistence of potentially infectious BCRV in unfed swallow bugs for at least 2 yr in nature.
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Affiliation(s)
- Charles R Brown
- Department of Biological Sciences, University of Tulsa, Tulsa, OK 74104, USA.
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Sisterson MS. Transmission of insect-vectored pathogens: effects of vector fitness as a function of infectivity status. ENVIRONMENTAL ENTOMOLOGY 2009; 38:345-355. [PMID: 19389282 DOI: 10.1603/022.038.0206] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The transmission of insect-vectored pathogens is dependent on the population dynamics of the vector. Epidemiological models typically assume that birth and death rates of pathogen-free and inoculative vectors are equal, an assumption that is not true for all pathosystems. Here, a series of simple and general epidemiological models were used to explore how assumptions about birth and death rates of vectors based on their infectivity status influence disease incidence. With fixed death rate of pathogen-free vectors, increasing the death rate of inoculative vectors reduced vector density, the proportion of vectors that were inoculative, and the proportion of hosts infected. This effect was mediated by acquisition rate. Specifically, increasing the acquisition rate increased the proportion of vectors that were inoculative, thereby increasing the proportion of the vector population that experienced the increased death rate. With fixed birth rate of pathogen-free vectors, variation in birth rate of inoculative vectors had little influence on disease incidence provided that the birth rate of pathogen-free vectors was much greater than their death rate. However, when the birth rate of pathogen-free vectors was only slightly greater than their death rate, large increases in the birth rate of inoculative vectors increased total vector density and disease incidence. The results indicate that assumptions about birth and death rates of vectors based on infectivity status can have important effects on the vector population that in turn affects disease incidence.
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Affiliation(s)
- Mark S Sisterson
- USDA-ARS, San Joaquin Valley Agricultural Sciences Center, Parlier, CA 93648, USA.
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Suppression of RNA interference increases alphavirus replication and virus-associated mortality in Aedes aegypti mosquitoes. BMC Microbiol 2009; 9:49. [PMID: 19265532 PMCID: PMC2660349 DOI: 10.1186/1471-2180-9-49] [Citation(s) in RCA: 110] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2008] [Accepted: 03/05/2009] [Indexed: 01/06/2023] Open
Abstract
Background Arthropod-borne viruses (arboviruses) can persistently infect and cause limited damage to mosquito vectors. RNA interference (RNAi) is a mosquito antiviral response important in restricting RNA virus replication and has been shown to be active against some arboviruses. The goal of this study was to use a recombinant Sindbis virus (SINV; family Togaviridae; genus Alphavirus) that expresses B2 protein of Flock House virus (FHV; family Nodaviridae; genus Alphanodavirus), a protein that inhibits RNAi, to determine the effects of linking arbovirus infection with RNAi inhibition. Results B2 protein expression from SINV (TE/3'2J) inhibited the accumulation of non-specific small RNAs in Aedes aegypti mosquito cell culture and virus-specific small RNAs both in infected cell culture and Ae. aegypti mosquitoes. More viral genomic and subgenomic RNA accumulated in cells and mosquitoes infected with TE/3'2J virus expressing B2 (TE/3'2J/B2) compared to TE/3'2J and TE/3'2J virus expressing GFP. TE/3'2J/B2 exhibited increased infection rates, dissemination rates, and infectious virus titers in mosquitoes following oral bloodmeal. Following infectious oral bloodmeal, significantly more mosquitoes died when TE/3'2J/B2 was ingested. The virus was 100% lethal following intrathoracic inoculation of multiple mosquito species and lethality was dose-dependent in Ae. aegypti. Conclusion We show that RNAi is active in Ae. aegypti cell culture and that B2 protein inhibits RNAi in mosquito cells when expressed by a recombinant SINV. Also, SINV more efficiently replicates in mosquito cells when RNAi is inhibited. Finally, TE/3'2J/B2 kills mosquitoes in a dose-dependent manner independent of infection route and mosquito species.
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Lambrechts L, Scott TW. Mode of transmission and the evolution of arbovirus virulence in mosquito vectors. Proc Biol Sci 2009; 276:1369-78. [PMID: 19141420 PMCID: PMC2660968 DOI: 10.1098/rspb.2008.1709] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The traditional assumption that vector-borne pathogens should evolve towards a benign relationship with their arthropod vectors has been challenged on theoretical grounds and empirical evidence. However, in the case of arboviruses (arthropod-borne viruses), although a number of investigators have reported experimental evidence for virus-induced vector mortality, others have failed to detect any significant impact. Whether this variation in the observed level of arbovirus virulence depends on biological traits or experimental design is unclear. Here, we perform a meta-analysis of studies across a range of mosquito-virus systems to show that, overall, arboviruses do reduce the survival of their mosquito vectors, but that the magnitude of the effect depends on the vector/virus taxonomic groups and the mode of virus transmission. Alphaviruses were associated with highest virulence levels in mosquitoes. Horizontal transmission (intrathoracic inoculation or oral infection) was correlated with significant virus-induced mortality, whereas a lack of adverse effect was found for Aedes mosquitoes infected transovarially by bunyaviruses-a group of viruses characterized by high natural rates of vertical transmission in their enzootic vectors. Our findings are consistent with the general prediction that vertically transmitted pathogens should be less virulent than those transmitted horizontally. We conclude that varying degrees of virulence observed among vector-virus systems probably reflect different selective pressures imposed on arboviruses that are primarily transmitted horizontally versus vertically.
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Affiliation(s)
- Louis Lambrechts
- Department of Entomology, University of California, One Shields Avenue, Davis, CA 95616, USA.
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Bennett KE, Hopper JE, Stuart MA, West M, Drolet BS. Blood-feeding behavior of vesicular stomatitis virus infected Culicoides sonorensis (Diptera: Ceratopogonidae). JOURNAL OF MEDICAL ENTOMOLOGY 2008; 45:921-926. [PMID: 18826036 DOI: 10.1603/0022-2585(2008)45[921:bbovsv]2.0.co;2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
To determine whether vesicular stomatitis virus (VSV) infection of Culicoides sonorensis Wirth & Jones (Diptera: Ceratopogonidae) affects subsequent blood-feeding behavior, midges injected with either virus-infected or virus-free cell lysates were allowed to blood feed for short (10-min) or long (60-min) periods on 2, 3, and 4 d postinoculation (DPI). Generalized linear mixed models were fit to test the effects of infection status, duration of feeding period, and DPI on the percentage of females that blood fed. VSV-infection significantly reduced the percentage of females that blood fed on 2 DPI, the day of peak virus titer. On 3 DPI a significantly greater percentage of midges blood fed when allowed 60 min to feed. This effect was not seen on 2 and 4 DPI and was not dependent on VSV infection status. The impact of changes in blood-feeding behavior by infected insects on virus transmission is discussed.
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Affiliation(s)
- Kristine E Bennett
- USDA-ARS, Arthropod-Borne Animal Diseases Research Laboratory, Ag Bldg., Room 5031, Department 3354, 1000 E. University Ave., Laramie, WY 82071, USA.
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Bevins SN. Invasive mosquitoes, larval competition, and indirect effects on the vector competence of native mosquito species (Diptera: Culicidae). Biol Invasions 2007. [DOI: 10.1007/s10530-007-9188-8] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Styer LM, Meola MA, Kramer LD. West Nile virus infection decreases fecundity of Culex tarsalis females. JOURNAL OF MEDICAL ENTOMOLOGY 2007; 44:1074-1085. [PMID: 18047209 DOI: 10.1603/0022-2585(2007)44[1074:wnvidf]2.0.co;2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
West Nile virus (family Flaviviridae, genus Flavivirus, WNV) persistently infects many mosquito tissues, and it has been associated with cytopathological changes in midgut muscles and salivary glands. However, the effects of WNV infection on mosquito fitness (survival and reproduction) are not known. We conducted a life table study of individually housed female Culex tarsalis Coquillett. After an initial bloodmeal from a WNV-infected or uninfected chicken, mosquitoes were provided sucrose and offered weekly opportunities to feed on a hanging blood drop. WNV transmission status was determined by testing the remaining blood drop for virus after mosquito feeding. Dead mosquitoes and eggs were collected daily. Mosquito legs and bodies were tested for WNV, and eggs were counted and allowed to hatch. Two replicates of this experiment were performed, with a total of 62 mosquitoes that fed on a WNV-infected chicken (of which 21 became infected) and 43 mosquitoes that fed on an uninfected chicken. Fecundity of WNV-infected mosquitoes was significantly lower than that of uninfected mosquitoes, especially during the first oviposition. WNV infection was associated with smaller egg rafts, whereas increasing wing length and WNV titer in the legs had a positive effect on egg raft size. Additionally, infected mosquitoes had lower egg hatch rates than did uninfected mosquitoes. There were no significant differences in survival between infected and uninfected mosquitoes. Blood feeding rates were higher in infected mosquitoes than in uninfected mosquitoes. A small amount of virus (average, 378; range, 5-5000 plaque-forming units) was transmitted to the blood drops fed upon by infected mosquitoes. Although WNV infection negatively impacts mosquito reproduction, facets of mosquito biology that are critical to virus transmission success were either not affected (survival) or changed in such a way as to result in enhanced vectorial capacity (blood feeding).
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Affiliation(s)
- Linda M Styer
- Arbovirus Laboratories, Wadsworth Center, New York State Department of Health, Albany, NY 12159, USA
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Wonham MJ, Lewis MA, Rencławowicz J, van den Driessche P. Transmission assumptions generate conflicting predictions in host-vector disease models: a case study in West Nile virus. Ecol Lett 2006; 9:706-25. [PMID: 16706915 DOI: 10.1111/j.1461-0248.2006.00912.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This review synthesizes the conflicting outbreak predictions generated by different biological assumptions in host-vector disease models. It is motivated by the North American outbreak of West Nile virus, an emerging infectious disease that has prompted at least five dynamical modelling studies. Mathematical models have long proven successful in investigating the dynamics and control of infectious disease systems. The underlying assumptions in these epidemiological models determine their mathematical structure, and therefore influence their predictions. A crucial assumption is the host-vector interaction encapsulated in the disease-transmission term, and a key prediction is the basic reproduction number, R(0). We connect these two model elements by demonstrating how the choice of transmission term qualitatively and quantitatively alters R(0) and therefore alters predicted disease dynamics and control implications. Whereas some transmission terms predict that reducing the host population will reduce disease outbreaks, others predict that this will exacerbate infection risk. These conflicting predictions are reconciled by understanding that different transmission terms apply biologically only at certain population densities, outside which they can generate erroneous predictions. For West Nile virus, R(0) estimates for six common North American bird species indicate that all would be effective outbreak hosts.
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Affiliation(s)
- Marjorie J Wonham
- Department of Biological Sciences, Centre for Mathematical Biology, University of Alberta, CAB 632, Edmonton, AB, Canada T6G 2G1.
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Derraik JGB. Exotic mosquitoes in New Zealand: a review of species intercepted, their pathways and ports of entry. Aust N Z J Public Health 2005; 28:433-44. [PMID: 15707185 DOI: 10.1111/j.1467-842x.2004.tb00025.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
A review was carried out to identify the exotic mosquito species intercepted in New Zealand to 2004, together with their origins, pathways and ports of entry into the country. A total of 171 interceptions have been recorded since 1929. There was little or no taxonomic information available for many, but at least 27 exotic species not yet established in New Zealand have been intercepted, including important disease vectors such as Aedes albopictus, Aedes aegypti and Culex annulirostris. Of 152 interception records with a described origin, 100 (66%) have originated from the South Pacific, 42 (28%) from Australia alone, while Japan was the likely source for 22 (15%) interceptions and has become the main source of exotic mosquitoes since the 1990s. Aircraft have clearly been the main vessel for invading mosquitoes with 94 (62%) of 151 cases with a described entrance pathway, but that pattern has changed greatly in the past 15 years, with 51 (82%) of 62 interceptions occurring on ships. Auckland, New Zealand's largest city, has been the main port of entry for invaders (75/93; 81%). The data indicate that it is somewhat fortunate that New Zealand has only four exotic mosquito species established. It is necessary, therefore, to adopt comprehensive exotic species monitoring and border surveillance, with particular emphasis on incoming ships and their cargo, in order to stop further mosquito invasions that could potentially lead to future outbreaks of mosquito-borne diseases.
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Affiliation(s)
- José G B Derraik
- Ecology and Health Research Centre, Department of Public Health, Wellington School of Medicine and Health Sciences, University of Otago, New Zealand.
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Derraik JGB. Exotic mosquitoes in New Zealand: a review of species intercepted, their pathways and ports of entry. Aust N Z J Public Health 2004. [DOI: 10.1111/j.1467-842x.2004.tb00942.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
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Bowers DF, Coleman CG, Brown DT. Sindbis virus-associated pathology in Aedes albopictus (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:698-705. [PMID: 14596286 DOI: 10.1603/0022-2585-40.5.698] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Virus dissemination and associated pathology were examined in Aedes albopictus after intrathoracic inoculation of Sindbis virus (SIN), the prototypic Alphavirus. At 10 days postinfection, virus RNA was detected in all three-body segments of the insect. Colocalization of virus antigen with structural pathology was observed in mosquito salivary glands and midgut-associated visceral muscles, representing yet another example of arbovirus-associated pathology in a mosquito host. SIN antigen and gross pathology were detected in lateral lobes, but not the medial lobe of salivary glands, whereas virus antigen, vacuolated cytoplasm, and myofilament misalignment were detected in the visceral muscles at the midgut exterior surface. Early in the midgut infection, virus antigen was localized in small foci on the organ surface that progressed to a grate work-like banding pattern that eventually cleared. Both the salivary glands and the midgut are essential to insect survival and reproduction. Additionally, these organs provide a pathway for virus transmission in nature. Although SIN infection may not shorten the mosquito life span, persistent coexistence could permit survival of both host and microbe as well as contribute to alterations in insect behavior.
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Affiliation(s)
- Doria F Bowers
- Department of Biology, University of North Florida, Jacksonville, FL 32224-2661, USA
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Fernández Z, Moncayo AC, Carrara AS, Forattini OP, Weaver SC. Vector competence of rural and urban strains of Aedes (Stegomyia) albopictus (Diptera: Culicidae) from São Paulo State, Brazil for IC, ID, and IF subtypes of Venezuelan equine encephalitis virus. JOURNAL OF MEDICAL ENTOMOLOGY 2003; 40:522-527. [PMID: 14680121 DOI: 10.1603/0022-2585-40.4.522] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Aedes albopictus (Skuse) is an Asiatic mosquito species that has spread and colonized all continents except Antarctica. It has major public health importance because it is a potential vector of several pathogens. The objectives of our study were to analyze the vector competence of urban and rural strains of Ae. albopictus from São Paulo State (Brazil) for Venezuelan equine encephalitis virus (VEE) subtypes IC, ID, and IF, and to evaluate the effect of infection with subtype IC of VEE on mosquito longevity. Both mosquito strains were susceptible to subtypes IC and ID, but the infection rate for subtype IF was low. Infection and transmission rates of Ae. albopictus for subtype IC were similar to those reported for Ochlerotatus taeniorhynchus (Wiedemann). The high infection, dissemination, and transmission rates for subtype ID reported for Oc. fulvus (Wiedemann) and Culex (Melanoconion) spp. are comparable with those found in this study. We found significant differences in the susceptibility to subtype IC between rural and urban populations of São Paulo. Significant survival rate differences were observed between uninfected and infected mosquitoes, but there were no differences in survival between rural and urban mosquito strains.
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Affiliation(s)
- Z Fernández
- National Institution of Hygiene Rafael Rangel, Ap. Postal 60412, Caracas, Venezuela
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Kay BH, Jennings CD. Enhancement or modulation of the vector competence of Ochlerotatus vigilax (Diptera: Culicidae) for ross river virus by temperature. JOURNAL OF MEDICAL ENTOMOLOGY 2002; 39:99-105. [PMID: 11931278 DOI: 10.1603/0022-2585-39.1.99] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Two different doses of Ross River virus (RR) were fed to Ochlerotatus vigilax (Skuse), the primary coastal vector in Australia; and blood engorged females were held at different temperatures up to 35 d. After ingesting 10(4.3) CCID50/mosquito, mosquitoes reared at 18 and 25 degrees C (and held at the same temperature) had higher body remnant and head and salivary gland titers than those held at 32 degrees C. although infection rates were comparable. At 18, 25, and 32 degrees C, respectively, virus was first detected in the salivary glands on days 3, 2, and 3. Based on a previously demonstrated 98.7% concordance between salivary gland infection and transmission, the extrinsic incubation periods were estimated as 5, 4, and 3 d, respectively, for these three temperatures. When Oc. vigilax reared at 18, 25, or 32 degrees C were fed a lower dosage of 10(3.3) CCID50 RR/mosquito, and assayed after 7 d extrinsic incubation at these (or combinations of these) temperatures, infection rates and titers were similar. However, by 14 d, infection rates and titers of those reared and held at 18 and 32 degrees C were significantly higher and lower, respectively. However, this process was reversible when the moderate 25 degrees C was involved, and intermediate infection rates and titers resulted. These data indicate that for the strains of RR and Oc. vigilax used, rearing temperature is unimportant to vector competence in the field, and that ambient temperature variations will modulate or enhance detectable infection rates only after 7 d extrinsic incubation. Because of the short duration of extrinsic incubation, however, this will do little to influence RR epidemiology, because by this time some Oc. vigilax could be seeking their third blood meal, the latter two being infectious.
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Affiliation(s)
- B H Kay
- Queensland Institute of Medical Research and University of Queensland Tropical Health Program, Royal Brisbane Hospital, Australia.
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