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Detection of Wuchereria bancrofti in the city of São Luís, state of Maranhão, Brazil: New incursion or persisting problem? PLoS Negl Trop Dis 2023; 17:e0011091. [PMID: 36716339 PMCID: PMC9910792 DOI: 10.1371/journal.pntd.0011091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 02/09/2023] [Accepted: 01/11/2023] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND The elimination of lymphatic filariasis (LF) from Brazil by 2020 was not accomplished; however, this goal can be achieved in the upcoming years with the assistance of specific strategies. The surveillance of LF can be performed using molecular xenomonitoring (MX), a noninvasive method used to infer the presence of the parasite in the human population. Herein, São Luís (state of Maranhão) was the first city to be investigated to identify whether LF transmission in Brazil has been interrupted and if there were any new incursions. METHODOLOGY/PRINCIPAL FINDINGS Mosquitoes were collected by aspiration at 901 points distributed among 11 neighborhoods in São Luís with records of patients with microfilaremia. Pools of engorged or gravid Culex quinquefasciatus females were evaluated by WbCx duplex PCR with endogenous control for mosquitoes and target for W. bancrofti for determining the vector infection rate. Among the 10,428 collected mosquitoes, the most abundant species were C. quinquefasciatus (85%) and Aedes aegypti (12%). Significantly larger numbers of mosquitoes were collected from the neighborhoods of Areinha and Coreia (p<0.05). MX performed using PCR validated 705 pools of engorged or gravid females, fifteen of which were positive for Wuchereria bancrofti in two neighborhoods. CONCLUSIONS The high density of engorged C. quinquefasciatus females per home, inadequate sanitation, and detection of W. bancrofti-infected mosquitoes in the city of São Luís represent a warning of the possible upsurge of LF, a disease that is still neglected; this underscores the need for the ostensive monitoring of LF in Brazil.
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Ochi A, Bannai H, Aonuma H, Kanuka H, Uchida-Fujii E, Kinoshita Y, Ohta M, Kambayashi Y, Tsujimura K, Ueno T, Nemoto M. Surveillance of Getah virus in mosquitoes and racehorses from 2016 to 2019 at a training center in Ibaraki Prefecture, Japan, a site of several previous Getah virus outbreaks. Arch Virol 2023; 168:35. [PMID: 36609628 DOI: 10.1007/s00705-022-05631-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 10/09/2022] [Indexed: 01/09/2023]
Abstract
Mosquitoes and EDTA-treated blood samples from febrile racehorses were investigated for Getah virus infection from 2016 to 2019 at the Miho Training Center, where several outbreaks of Getah virus have occurred. We collected 5557 mosquitoes and 331 blood samples from febrile horses in this study. The most frequently captured mosquito species was Culex tritaeniorhynchus (51.9%), followed by Aedes vexans nipponii (14.2%) and Anopheles sinensis (11.2%). Getah virus was detected in mosquitoes (Aedes vexans nipponii) in 2016 (strain 16-0810-26) but not in 2017-2019. Six of 74 febrile horses in 2016 and one of 69 in 2019 tested positive for Getah virus; none of the horses tested positive in 2017 or 2018. Phylogenetic and sequence analysis showed that strain 16-0810-26 was closely related to strains that had been isolated from horses and a pig around the training center in 2014-2016 but have not been detected in samples collected at the training center since 2017. In contrast, the strain isolated from the infected horse in 2019 (19-I-703) was genetically distinct from the strains isolated from horses and a pig in 2014-2016 and was more closely related to a strain isolated in 1978 at the training center. The source of strain 19-I-703 is unclear, but the virus was not detected in other horses sampled in 2019. In summary, we found that the distribution of mosquito species present at the training center had not changed significantly since 1979, and although a small outbreak of Getah virus infection occurred among horses at the training center in 2016, limited Getah virus activity was detected in mosquitoes and horses at the training center from 2017 to 2019.
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Affiliation(s)
- Akihiro Ochi
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Hiroshi Bannai
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Hiroka Aonuma
- Department of Tropical Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Hirotaka Kanuka
- Department of Tropical Medicine, Jikei University School of Medicine, Tokyo, Japan
| | - Eri Uchida-Fujii
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Yuta Kinoshita
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Minoru Ohta
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Yoshinori Kambayashi
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Koji Tsujimura
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Takanori Ueno
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan
| | - Manabu Nemoto
- Equine Research Institute, Japan Racing Association, 1400-4 Shiba, Shimotsuke, Tochigi, 329-0412, Japan.
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Reyes-Proaño E, Alvarez-Quinto R, Delgado-Jiménez JA, Cornejo-Franco JF, Mollov D, Bejerman N, Quito-Avila DF. Genome Characterization and Pathogenicity of Two New Hyptis pectinata Viruses Transmitted by Distinct Insect Vectors. PHYTOPATHOLOGY 2022; 112:2440-2448. [PMID: 35694887 DOI: 10.1094/phyto-04-22-0130-r] [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: 06/15/2023]
Abstract
Two newly described viruses belonging to distinct families, Rhabdoviridae and Geminiviridae, were discovered co-infecting Hyptis pectinata from a tropical dry forest of Ecuador. The negative-sense RNA genome of the rhabdovirus, tentatively named Hyptis latent virus (HpLV), comprises 13,765 nucleotides with seven open reading frames separated by the conserved intergenic region 3'-AAUUAUUUUGAU-5'. Sequence analyses showed identities as high as 56% for the polymerase and 38% for the nucleocapsid to members of the genus Cytorhabdovirus. Efficient transmission of HpLV was mediated by the pea aphid (Acyrthosiphon pisum) in a persistent replicative manner. The single-stranded DNA genome of the virus tentatively named Hyptis golden mosaic virus (HpGMV) shared homology with members of the genus Begomovirus with bipartite genomes. The DNA-A component consists of 2,716 nucleotides (nt), whereas the DNA-B component contains 2,666 nt. Pairwise alignments using the complete genomic sequence of DNA-A of HpGMV and closest relatives showed identities below the cutoff (<91% shared nt) established by the ICTV as species demarcation, indicating that HpGMV should be classified in a distinct begomovirus species. Transmission experiments confirmed that the whitefly Bemisia tabaci Middle East-Asia Minor 1 (MEAM1) is a vector of HpGMV.
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Affiliation(s)
- Edison Reyes-Proaño
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral (ESPOL), Guayaquil, Guayas, Ecuador
| | - Robert Alvarez-Quinto
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, U.S.A
| | - José A Delgado-Jiménez
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral (ESPOL), Guayaquil, Guayas, Ecuador
| | - Juan F Cornejo-Franco
- Centro de Investigaciones Biotecnológicas del Ecuador (CIBE), Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Guayas, Ecuador
| | - Dimitre Mollov
- USDA-ARS, Horticultural Crops Disease and Pest Management Research Unit, Corvallis, OR, U.S.A
| | - Nicolás Bejerman
- Instituto de Patología Vegetal, Centro de Investigaciones Agropecuarias, Instituto Nacional de Tecnología Agropecuaria (IPAVE-CIAP-INTA), Camino 60 Cuadras Km 5.5, Córdoba X5020ICA, Argentina
- Consejo Nacional de Investigaciones Científicas y Técnicas, Unidad de Fitopatología y Modelización Agrícola, Camino 60 Cuadras Km 5.5, Córdoba X5020ICA, Argentina
| | - Diego F Quito-Avila
- Facultad de Ciencias de la Vida, Escuela Superior Politécnica del Litoral (ESPOL), Guayaquil, Guayas, Ecuador
- Centro de Investigaciones Biotecnológicas del Ecuador (CIBE), Escuela Superior Politécnica del Litoral, ESPOL, Guayaquil, Guayas, Ecuador
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Diniz DFA, Romão TP, Helvécio E, de Carvalho-Leandro D, Xavier MDN, Peixoto CA, de Melo Neto OP, Melo-Santos MAVD, Ayres CFJ. A comparative analysis of Aedes albopictus and Aedes aegypti subjected to diapause-inducing conditions reveals conserved and divergent aspects associated with diapause, as well as novel genes associated with its onset. CURRENT RESEARCH IN INSECT SCIENCE 2022; 2:100047. [PMID: 36683953 PMCID: PMC9846470 DOI: 10.1016/j.cris.2022.100047] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 09/28/2022] [Accepted: 09/29/2022] [Indexed: 05/05/2023]
Abstract
Aedes albopictus and Aedes aegypti are mosquito species that are distributed worldwide and transmit diverse arboviruses of medical importance, such as those causing yellow fever, dengue, chikungunya and Zika. A. albopictus embryos may remain viable for long periods in the environment due to their ability to become dormant through quiescence or diapause, a feature that contributes to their dispersion and hinders control actions. Diapause incidence can vary among natural populations of A. albopictus, but metabolic and genetic parameters associated with its induction still need to be better defined. The present study aimed to investigate the effect of exposure to diapause-inducing conditions on several biological parameters in different populations of A. albopictus (from tropical and temperate areas) and the diapause-refractory A. aegypti (tropical and subtropical populations). As expected, only the A. albopictus populations exhibited diapause, but with a lower incidence for the population from a tropical area. Exposure to diapause-inducing conditions, however, led to a sharp reduction in fecundity for both A. albopictus and A. aegypti tropical populations, with no effect on fertility (>90%). It also led to a prolonged period as pupae for the progeny of all induced groups, with a further delay for those from temperate climates. In all those induced groups, the lipid contents in eggs and adult females were higher than in the non-induced controls, with the highest values observed for both A. albopictus groups. Three genes were selected to have their expression profile investigated: cathepsin, idgf4, and pepck. Upon exposure to diapause-inducing conditions, all three genes were upregulated in the A. albopictus embryos from the tropical region, but only idgf4 was upregulated in the temperate climate embryos. This represents a new gene associated with diapause that can be used as a target to evaluate and prevent embryonic dormancy, a possible new vector control strategy for mosquito species from temperate areas, such as A. albopictus.
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Affiliation(s)
- Diego Felipe Araujo Diniz
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Tatiany Patrícia Romão
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
- Correspondence: Department of Entomology, Centro de Pesquisas Aggeu Magalhães-FIOCRUZ, Recife, PE 50670-420, Brazil.
| | - Elisama Helvécio
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Danilo de Carvalho-Leandro
- Colégio de Aplicação, Federal University of Pernambuco, Av. da Arquitetura, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Morgana do Nascimento Xavier
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Christina Alves Peixoto
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Osvaldo Pompílio de Melo Neto
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Maria Alice Varjal de Melo-Santos
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
| | - Constância Flávia Junqueira Ayres
- Entomology Department - Aggeu Magalhães Institute - Oswaldo Cruz Foundation, Av. Professor Moraes Rego, s/n, Cidade Universitária, Recife, PE, Brazil
- Correspondence: Department of Entomology, Centro de Pesquisas Aggeu Magalhães-FIOCRUZ, Recife, PE 50670-420, Brazil.
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Daidoji T, Morales Vargas RE, Hagiwara K, Arai Y, Watanabe Y, Nishioka K, Murakoshi F, Garan K, Sadakane H, Nakaya T. Development of genus-specific universal primers for the detection of flaviviruses. Virol J 2021; 18:187. [PMID: 34526049 PMCID: PMC8442469 DOI: 10.1186/s12985-021-01646-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/23/2021] [Indexed: 12/03/2022] Open
Abstract
Background Flaviviruses are representative arboviruses carried by arthropods and/or vertebrates; these viruses can pose a public health concern in many countries. By contrast, it is known that a novel virus group called insect-specific flaviviruses (ISFs) also infects arthropods, although no such virus has yet been isolated from vertebrates. The characteristics of ISFs, which affect replication of human-pathogenic flaviviruses within co-infected mosquito cells or mosquitoes without affecting the mosquitoes themselves, mean that we should pay attention to both ISFs and human-pathogenic flaviviruses, despite the fact that ISFs appear not to be directly hazardous to human health. To assess the risk of diseases caused by flaviviruses, and to better understand their ecology, it is necessary to know the extent to which flaviviruses are harbored by arthropods. Methods We developed a novel universal primer for use in a PCR-based system to detect a broad range of flaviviruses. We then evaluated its performance. The utility of the novel primer pair was evaluated in a PCR assay using artificially synthesized oligonucleotides derived from a template viral genome sequence. The utility of the primer pair was also examined by reverse transcription PCR (RT-PCR) using cDNA templates prepared from virus-infected cells or crude supernatants prepared from virus-containing mosquito homogenates. Results The novel primer pair amplified the flavivirus NS5 sequence (artificially synthesized) in all samples tested (six species of flavivirus that can cause infectious diseases in humans, and flaviviruses harbored by insects). In addition, the novel primer pair detected viral genomes in cDNA templates prepared from mosquito cells infected with live flavivirus under different infectious conditions. Finally, the viral genome was detected with high sensitivity in crude supernatants prepared from pooled mosquito homogenates. Conclusion This PCR system based on a novel primer pair makes it possible to detect arthropod-borne flaviviruses worldwide (the primer pair even detected viruses belonging to different genetic subgroups). As such, an assay based on this primer pair may help to improve public health and safety, as well as increase our understanding of flavivirus ecology. Supplementary Information The online version contains supplementary material available at 10.1186/s12985-021-01646-5.
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Affiliation(s)
- Tomo Daidoji
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan.
| | | | - Katsuro Hagiwara
- Veterinary Virology, School of Veterinary Medicine , Rakuno Gakuen University, Hokkaido, 069-8501, Japan
| | - Yasuha Arai
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Yohei Watanabe
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Keisuke Nishioka
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Fumi Murakoshi
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Kotaro Garan
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Hiroki Sadakane
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
| | - Takaaki Nakaya
- Department of Infectious Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 602-8566, Japan
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Munivenkatappa A, Nyayanit DA, Yadav PD, Rangappa M, Patil S, Majumdar T, Mohandas S, Sinha DP, Jayaswamy MM, OmPrakash P. Identification of Phasi Charoen-Like Phasivirus in Field Collected Aedes aegypti from Karnataka State, India. Vector Borne Zoonotic Dis 2021; 21:900-909. [PMID: 34520272 DOI: 10.1089/vbz.2021.0011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Background: A wide range of insect-specific viruses (ISVs) have been reported worldwide. There are no studies from India that have reported ISVs. The current study describes the identification of Phasi Charoen-like virus (PCLV) from Aedes aegypti mosquito-pools from six districts of Karnataka state, India. Materials and Methods: During the Chikungunya virus (CHIKV) outbreak in the Bangalore Urban district in 2019, using conventional PCR, it was found that both human and mosquito samples were positive for CHIKV. For retrieve the complete genome sequence, mosquito samples were subjected to next generation sequencing (NGS) analysis and PCLV was also found. During 2019, as part of a vector-borne disease surveillance, we received 50 mosquito pool samples from 6 districts of the state, all of them were subjected to NGS to identify PCLV. Results: The A. aegypti mosquito-pools samples were subjected to the NGS platform that led to identification of an ISV, PCLV. PCLV was identified in 26 A. aegypti mosquito-pools collected from 6 districts. We also found mixed infection of PCLV with the Dengue virus (DENV; genotypes 1 and 3) and CHIKV from five pools. The nucleotide identity for the L gene of Indian PCLV sequences ranged between 97.1% and 98.3% in comparison with the Thailand sequences. Conclusions: To the best of our knowledge, this is the first report of PCLV dual infection with DENV and CHIKV in India. The present study confirms the presence of PCLV in A. aegypti mosquitoes from Karnataka state. The study adds India in the global geographical distribution of PCLV.
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Affiliation(s)
- Ashok Munivenkatappa
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Bangalore, Karnataka, India
| | - Dimpal A Nyayanit
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Pune, Maharashtra, India
| | - Pragya D Yadav
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Pune, Maharashtra, India
| | - Manjushree Rangappa
- National Anti-Malaria Programme Bangalore Zone, Directorate of Health and Family Welfare Services, Bangalore, Karnataka, India
| | - Savita Patil
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Pune, Maharashtra, India
| | - Triparna Majumdar
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Pune, Maharashtra, India
| | - Sreelekshmy Mohandas
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Pune, Maharashtra, India
| | - Diamond Prakash Sinha
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Bangalore, Karnataka, India
| | - Manjunath M Jayaswamy
- Indian Council of Medical Research (ICMR)-National Institute of Virology, Bangalore, Karnataka, India
| | - Patil OmPrakash
- Directorate of Health and Family Welfare Services, Bangalore, Karnataka, India
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Evaluation of Actin-1 Expression in Wild Caught Wuchereria bancrofti-Infected Mosquito Vectors. J Pathog 2020; 2020:7912042. [PMID: 33062336 PMCID: PMC7547363 DOI: 10.1155/2020/7912042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Revised: 03/18/2020] [Accepted: 03/30/2020] [Indexed: 11/17/2022] Open
Abstract
Background Wuchereria bancrofti is the major cause of lymphatic filariasis transmitted by mosquito vectors. In the vector-parasite interaction and among other proteins, actin-1 has been implicated for successful transmission of the pathogen in laboratory-controlled experiments. However, validation of this finding from the pathogen's natural environment is required. Objective This study is aimed at evaluating actin-1 expression upon Wuchereria bancrofti infection in mosquito vectors collected during an epidemiology study in Tsafe Local Government Area of Zamfara State, Nigeria. Methods Mosquitoes were collected and identified using morphological keys, which include length of maxillary palps, pale spots on the wings, and scale patterns on the abdomen. This was followed by detection of the 188 bp SspI marker of Wuchereria bancrofti infection using polymerase chain reaction (PCR). The mRNA levels of the actin-1 gene were evaluated in the infected Anopheles gambiae sl and Culex quinquefasciatus and their controls, which were adult reared from the larvae in the study area. Results The mosquitoes were identified to be Anopheles gambiae sl and Culex quinquefasciatus, while infection by Wuchereria bancrofti was confirmed by amplification of the 188 bp SspI marker. A 4.85 and 4.09 relative fold increase in actin-1 gene expression in Wuchereria bancrofti-infected Anopheles gambiae sl and Culex quinquefasciatus was observed. Thus, for the first time we reported that the actin-1 gene in wild caught mosquito vectors (Anopheles gambiae sl and Culex quinquefasciatus) infected with Wuchereria bancrofti is upregulated. Conclusion The actin-1 gene is upregulated and similarly expressed during W. bancrofti infection in mosquito vectors in the study area and this may likely serve as a biomarker and viable strategy for the control of parasite transmission in endemic areas.
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Albuquerque ALD, Araújo TAD, Melo DCTVD, Paiva MHS, Melo FLD, Oliveira CMFD, Ayres CFJ. Development of a molecular xenomonitoring protocol to assess filariasis transmission. Exp Parasitol 2020; 215:107918. [PMID: 32464220 DOI: 10.1016/j.exppara.2020.107918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/16/2020] [Accepted: 05/14/2020] [Indexed: 11/30/2022]
Abstract
According to the World Health Organization, lymphatic filariasis (LF), a mosquito-borne neglected tropical disease (NTD), should be eliminated as a public health concern by the end of 2020. To this end, the goals of the Global Programme to Eliminate Lymphatic Filariasis (GPELF) include interrupting transmission through mass drug administration (MDA). After two decades, several countries have implemented MDA and are now ready to confirm whether transmission has been interrupted. The method for detecting the parasites in mosquito vectors known as xenomonitoring is a non-invasive tool for assessing the current transmission status of the filarial nematode Wuchereria bancrofti (which is responsible for 90% of cases) by their vectors. There are several methods available for detection of the worm in mosquito samples, such as dissection or polymerase chain reaction (PCR). However, most of these techniques still produce a considerable number of false-negative results. The present study describes a new duplex PCR protocol, which is an improvement on the traditional PCR methodology, enhanced by introducing the actin gene as an endogenous control gene. After adjusting the mosquito pool size, DNA extraction, and WbCx PCR duplex design, we achieved a reliable and sensitive molecular xenomonitoring protocol. This assay was able to eliminate 5% of false negative samples and detected less than one Wb larvae. This high sensitivity is particularly valuable after MDA, when prevalence declines. This new method could reduce the number of false-negative samples, which will enable us to improve our ability to generate accurate results and aid the monitoring strategies used by LF elimination programmes.
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Affiliation(s)
| | | | | | - Marcelo Henrique Santos Paiva
- Departamento de Entomologia, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz, Recife, Pernambuco, Brazil; Universidade Federal de Pernambuco, Centro Acadêmico do Agreste, Caruaru, Pernambuco, Brazil.
| | - Fábio Lopes de Melo
- Departamento de Parasitologia, Instituto Aggeu Magalhães, Fundação Oswaldo Cruz, Recife, Pernambuco, Brazil.
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Parry R, Naccache F, Ndiaye EH, Fall G, Castelli I, Lühken R, Medlock J, Cull B, Hesson JC, Montarsi F, Failloux AB, Kohl A, Schnettler E, Diallo M, Asgari S, Dietrich I, Becker SC. Identification and RNAi Profile of a Novel Iflavirus Infecting Senegalese Aedes vexans arabiensis Mosquitoes. Viruses 2020; 12:E440. [PMID: 32295109 PMCID: PMC7232509 DOI: 10.3390/v12040440] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 04/10/2020] [Accepted: 04/11/2020] [Indexed: 01/16/2023] Open
Abstract
The inland floodwater mosquito Aedes vexans (Meigen, 1830) is a competent vector of numerous arthropod-borne viruses such as Rift Valley fever virus (Phenuiviridae) and Zika virus (Flaviviridae). Aedes vexans spp. have widespread Afrotropical distribution and are common European cosmopolitan mosquitoes. We examined the virome of Ae. vexans arabiensis samples from Barkédji village, Senegal, with small RNA sequencing, bioinformatic analysis, and RT-PCR screening. We identified a novel 9494 nt iflavirus (Picornaviridae) designated here as Aedes vexans iflavirus (AvIFV). Annotation of the AvIFV genome reveals a 2782 amino acid polyprotein with iflavirus protein domain architecture and typical iflavirus 5' internal ribosomal entry site and 3' poly-A tail. Aedes vexans iflavirus is most closely related to a partial virus sequence from Venturia canescens (a parasitoid wasp) with 56.77% pairwise amino acid identity. Analysis of AvIFV-derived small RNAs suggests that AvIFV is targeted by the exogenous RNA interference pathway but not the PIWI-interacting RNA response, as ~60% of AvIFV reads corresponded to 21 nt Dicer-2 virus-derived small RNAs and the 24-29 nt AvIFV read population did not exhibit a "ping-pong" signature. The RT-PCR screens of archival and current (circa 2011-2020) Ae. vexans arabiensis laboratory samples and wild-caught mosquitoes from Barkédji suggest that AvIFV is ubiquitous in these mosquitoes. Further, we screened wild-caught European Ae. vexans samples from Germany, the United Kingdom, Italy, and Sweden, all of which tested negative for AvIFV RNA. This report provides insight into the diversity of commensal Aedes viruses and the host RNAi response towards iflaviruses.
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Affiliation(s)
- Rhys Parry
- Australian Infectious Diseases Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; (R.P.); (S.A.)
| | - Fanny Naccache
- Institute for Parasitology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - El Hadji Ndiaye
- Pole de Zoologie Médicale, Institut Pasteur de Dakar, Dakar BP 220, Senegal; (E.H.N.); (M.D.)
| | - Gamou Fall
- Pole de Virologie, Unité des Arbovirus et Virus de Fièvres Hémorragiques, Institut Pasteur de Dakar, Dakar BP 220, Senegal;
| | - Ilaria Castelli
- Arboviruses and Insect Vectors, Department of Virology, Institut Pasteur, 75724 Paris, France; (I.C.); (A.-B.F.)
| | - Renke Lühken
- Faculty of Mathematics, Informatics and Natural Sciences, Universiät Hamburg, 20148 Hamburg, Germany; (R.L.); (E.S.)
- Bernhard-Nocht-Institute for Tropical Medicine, 20359 Hamburg, Germany
| | - Jolyon Medlock
- Health Protection Research Unit in Emerging and Zoonotic Infection, Public Health England, Porton Down, Salisbury SP4 0JG, UK;
- Medical Entomology & Zoonoses Ecology, Emergency Response Department Science & Technology, Public Health England, Porton Down, Salisbury SP4 0JG, UK; or
| | - Benjamin Cull
- Medical Entomology & Zoonoses Ecology, Emergency Response Department Science & Technology, Public Health England, Porton Down, Salisbury SP4 0JG, UK; or
| | - Jenny C. Hesson
- Department of Medical Biochemistry and Microbiology/Zoonosis Science Center, Uppsala University, 75237 Uppsala, Sweden;
| | - Fabrizio Montarsi
- Laboratory of Parasitology, Istituto Zooprofilattico Sperimentale delle Venezie, 35020 Legnaro (Padua), Italy;
| | - Anna-Bella Failloux
- Arboviruses and Insect Vectors, Department of Virology, Institut Pasteur, 75724 Paris, France; (I.C.); (A.-B.F.)
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow G61 1QH, UK;
| | - Esther Schnettler
- Faculty of Mathematics, Informatics and Natural Sciences, Universiät Hamburg, 20148 Hamburg, Germany; (R.L.); (E.S.)
- Bernhard-Nocht-Institute for Tropical Medicine, 20359 Hamburg, Germany
- German Centre for Infection Research, partner site Hamburg-Lübeck-Borstel-Riems, 20359 Hamburg, Germany
| | - Mawlouth Diallo
- Pole de Zoologie Médicale, Institut Pasteur de Dakar, Dakar BP 220, Senegal; (E.H.N.); (M.D.)
| | - Sassan Asgari
- Australian Infectious Diseases Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia; (R.P.); (S.A.)
| | | | - Stefanie C. Becker
- Institute for Parasitology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany;
- Research Center for Emerging Infections and Zoonoses, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
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10
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Gravina HD, Suzukawa AA, Zanluca C, Cardozo Segovia FM, Tschá MK, Martins da Silva A, Faoro H, da Silva Ribeiro R, Mendoza Torres LP, Rojas A, Ferrerira L, Costa Ribeiro MCVD, Delfraro A, Duarte Dos Santos CN. Identification of insect-specific flaviviruses in areas of Brazil and Paraguay experiencing endemic arbovirus transmission and the description of a novel flavivirus infecting Sabethes belisarioi. Virology 2018; 527:98-106. [PMID: 30476788 DOI: 10.1016/j.virol.2018.11.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 11/15/2018] [Accepted: 11/15/2018] [Indexed: 11/26/2022]
Abstract
Viral infection was examined with pan-flavivirus and pan-alphavirus sets of primers in mosquitoes collected in four South American regions with confirmed pathogenic arbovirus circulation. Positive pools for flavivirus infection were sequenced and screened for specific arboviruses, which were not detected. However, NS5 gene sequencing showed that most sequences corresponded to the insect-specific Culex flavivirus. One sequence retrieved from an Aedes albopictus pool grouped with the insect-specific Aedes flavivirus and two Sabethes belisarioi pools were infected by a previously unknown flavivirus, tentatively named Sabethes flavivirus (SbFV). Phylogenetic inference placed SbFV as ancestral to a clade formed by Culiseta flavivirus, Mercadeo, and Calbertado. SbFV polyprotein showed an average aminoacidic identity of 51% in comparison to these flaviviruses. In vitro studies suggest that SbFV infects insect cells, but not vertebrate cells, therefore, we propose it as a new insect-specific flavivirus. These results highlight the wide distribution of insect-specific flaviviruses concomitant with the circulation of emergent arboviruses.
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Affiliation(s)
| | - Andreia Akemi Suzukawa
- Laboratório de Virologia Molecular, Instituto Carlos Chagas/Fiocruz-PR, Curitiba, PR, Brazil
| | - Camila Zanluca
- Laboratório de Virologia Molecular, Instituto Carlos Chagas/Fiocruz-PR, Curitiba, PR, Brazil
| | - Fatima María Cardozo Segovia
- Departamento de Salud Pública, Instituto de Investigaciones en Ciencias de la Salud (IICS), Universidad Nacional de Asunción (UNA), Paraguay
| | - Marcel Kruchelski Tschá
- Laboratório de Virologia Molecular, Instituto Carlos Chagas/Fiocruz-PR, Curitiba, PR, Brazil
| | - Allan Martins da Silva
- Laboratório Central, Secretaria de Estado da Saúde (SESA), São José dos Pinhais, PR, Brazil
| | - Helisson Faoro
- Laboratório de Regulação da Expressão Gênica (LRGEN), Instituto Carlos Chagas/Fiocruz-PR, Curitiba, PR, Brazil
| | - Ricardo da Silva Ribeiro
- Laboratório de Vigilância Ambiental, Centro de Vigilância em Saúde Ambiental (CVSA), Secretaria de Estado de Saúde (SESA), Vitória, ES, Brazil
| | - Laura Patricia Mendoza Torres
- Departamento de Salud Pública, Instituto de Investigaciones en Ciencias de la Salud (IICS), Universidad Nacional de Asunción (UNA), Paraguay
| | - Alejandra Rojas
- Departamento de Salud Pública, Instituto de Investigaciones en Ciencias de la Salud (IICS), Universidad Nacional de Asunción (UNA), Paraguay
| | - Luis Ferrerira
- Servicio Nacional de Erradicación del Paludismo (SENEPA), Ministerio de Salud Pública y Bienestar Social, Asunción, Paraguay
| | | | - Adriana Delfraro
- Sección Virología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
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11
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Iwashita H, Higa Y, Futami K, Lutiali PA, Njenga SM, Nabeshima T, Minakawa N. Mosquito arbovirus survey in selected areas of Kenya: detection of insect-specific virus. Trop Med Health 2018; 46:19. [PMID: 29991925 PMCID: PMC5987586 DOI: 10.1186/s41182-018-0095-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 04/04/2018] [Indexed: 11/29/2022] Open
Abstract
Background Many arboviral outbreaks have occurred in various locations in Kenya. Entomological surveys are suitable methods for revealing information about circulating arboviruses before human outbreaks are recognized. Therefore, mosquitoes were collected in Kenya to determine the distribution of arboviruses. Methods Various species of mosquitoes were sampled from January to July 2012 using several collection methods. Mosquito homogenates were directly tested by reverse transcription-polymerase chain reaction (RT-PCR) using various arbovirus-targeted primer pairs. Results We collected 12,569 mosquitoes. Although no human-related arboviruses were detected, Culex flavivirus (CxFV), an insect-specific arbovirus, was detected in 54 pools of 324 Culex quinquefasciatus individuals collected during the rainy season. Of these 54 positive pools, 96.3% (52/54) of the mosquitoes were collected in Busia, on the border of western Kenya and Uganda. The remaining two CxFV-positive pools were collected in Mombasa and Kakamega, far from Busia. Phylogenetic analysis revealed minimal genetic diversity among the CxFVs collected in Mombasa, Kakamega, and Busia, even though these cities are in geographically different regions. Additionally, CxFV was detected in one mosquito pool collected in Mombasa during the dry season. In addition to Culex mosquitoes, Aedes (Stegomyia) and Anopheles mosquitoes were also positive for the Flavivirus genus. Cell fusing agent virus was detected in one pool of Aedes aegypti. Mosquito flavivirus was detected in three pools of Anopheles gambiae s.l. collected in the dry and rainy seasons. Conclusions Although no mosquitoes were positive for human-related arbovirus, insect-specific viruses were detected in various species of mosquitoes. The heterogeneity observed in the number of CxFVs in Culex mosquitoes in different locations in Kenya suggests that the abundance of human-related viruses might differ depending on the abundance of insect-specific viruses. We may have underestimated the circulation of any human-related arbovirus in Kenya, and the collection of larger samples may allow for determination of the presence of human-related arboviruses.
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Affiliation(s)
- Hanako Iwashita
- 1Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523 Japan.,2Department of Bacteriology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishiharacho, Okinawa, 903-0125 Japan
| | - Yukiko Higa
- 1Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523 Japan
| | - Kyoko Futami
- 1Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523 Japan
| | - Peter A Lutiali
- 3NUITM-KEMRI Project, Kenya Medical Research Institute, Nairobi, Kenya
| | - Sammy M Njenga
- 4Eastern and Southern Africa Centre of International Parasite Control (ESACIPAC), Kenya Medical Research Institute, Nairobi, Kenya
| | - Takeshi Nabeshima
- 5Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Noboru Minakawa
- 1Department of Vector Ecology and Environment, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki, 852-8523 Japan
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12
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Lumley S, Hernández-Triana LM, Horton DL, Fernández de Marco MDM, Medlock JM, Hewson R, Fooks AR, Johnson N. Competence of mosquitoes native to the United Kingdom to support replication and transmission of Rift Valley fever virus. Parasit Vectors 2018; 11:308. [PMID: 29776384 PMCID: PMC5960175 DOI: 10.1186/s13071-018-2884-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/02/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Rift Valley fever phlebovirus (RVFV) is a mosquito-borne arbovirus causing severe disease in humans and livestock. It is endemic in Africa and spread to the Arabian Peninsula in 2000 raising concerns it could emerge in Europe. The ability of temperate mosquitoes from the United Kingdom (UK) to support replication and transmission of RVFV is unknown. METHODS In this study, two colonised lines of Culex pipiens, wild-caught Aedes detritus and Ae. rusticus from the UK were infected with pathogenic strains of RVFV to assess their vector competence. Mosquitoes were offered artificial blood-meals containing 106 or 107 plaque forming units (PFU)/ml RVFV, simulating natural peak viraemia in young ruminants, and maintained at 20 °C or 25 °C for up to 21 days. Bodies, legs and saliva were collected and tested for the presence of viral RNA and infectious virus to determine the infection, dissemination and transmission potential. RESULTS Across temperatures, doses and strains the average infection, dissemination and transmission rates were: 35, 13 and 5% (n = 91) for Cx. pipiens (Caldbeck); 23, 14 and 5% (n = 138) for Cx. pipiens (Brookwood); 36, 28 and 7% (n = 118) for Ae. detritus. However, despite 35% (n = 20) being susceptible to infection, Ae. rusticus did not transmit RVFV. Survival of Aedes species was negatively affected by maintenance at 25 °C compared to the more representative peak average British summer temperature of 20 °C. Increased mortality was also observed with some species infected with 107 PFU/ml compared to 106 PFU/ml. CONCLUSIONS It can be concluded that temperate mosquito species present in the UK demonstrate a transmission potential for RVFV in the laboratory but, even at high temperatures, this occurred at low efficiency.
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Affiliation(s)
- Sarah Lumley
- Microbiology Services Division, Public Health England, Wiltshire, UK. .,School of Veterinary Medicine, University of Surrey, Guildford, UK. .,Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Addlestone, Surrey, UK.
| | - Luis M Hernández-Triana
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Addlestone, Surrey, UK
| | - Daniel L Horton
- School of Veterinary Medicine, University of Surrey, Guildford, UK
| | | | - Jolyon M Medlock
- Microbiology Services Division, Public Health England, Wiltshire, UK
| | - Roger Hewson
- Microbiology Services Division, Public Health England, Wiltshire, UK.,NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK
| | - Anthony R Fooks
- Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Addlestone, Surrey, UK.,NIHR Health Protection Research Unit in Emerging and Zoonotic Infections, University of Liverpool, Liverpool, UK.,Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, UK
| | - Nicholas Johnson
- School of Veterinary Medicine, University of Surrey, Guildford, UK.,Wildlife Zoonoses and Vector-borne Diseases Research Group, Animal and Plant Health Agency, Addlestone, Surrey, UK
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13
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Jiang F, Liang L, Li Z, Yu Y, Wang J, Wu Y, Zhu S. A conserved motif within cox 2 allows broad detection of economically important fruit flies (Diptera: Tephritidae). Sci Rep 2018; 8:2077. [PMID: 29391551 PMCID: PMC5794786 DOI: 10.1038/s41598-018-20555-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 01/19/2018] [Indexed: 11/09/2022] Open
Abstract
The genera Anastrepha, Bactrocera, Ceratitis, Dacus and Rhagoletis in the family Tephritidae order Diptera are economically important, worldwide distributed and cause damage to a large number of commercially produced fruits and vegetables. China had regulated these five genera as quarantine pests, including the species Carpomya vesuviana. An accurate molecular method not depending on morphology able to detect all the quarantine fruit flies simultaneously is required for quarantine monitoring. This study contributes a comparative analysis of 146 mitochondrial genomes of Diptera species and found variable sites at the mt DNA cox2 gene only conserved in economically important fruit flies species. Degenerate primers (TephFdeg/TephR) were designed specific for the economically important fruit flies. A 603 bp fragment was amplified after testing each of the 40 selected representative species belonging to each economically important Tephritid genera, no diagnostic fragments were detected/amplified in any of the other Tephritidae and Diptera species examined. PCR sensitivity assays demonstrated the limit of detection of targeted DNA was 0.1 ng/μl. This work contributes an innovative approach for detecting all reported economically important fruit flies in a single-step PCR specific for reported fruit fly species of quarantine concern in China.
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Affiliation(s)
- Fan Jiang
- Chinese Academy of Inspection and Quarantine, Beijing, 100176, China
| | - Liang Liang
- Key Laboratory of Agro-Products Postharvest Handling, Ministry of Agriculture, Chinese Academy of Agricultural Engineering, Beijing, 100121, China
| | - Zhihong Li
- College of Plant Protection, China Agricultural University, Beijing, 100193, China.
| | - Yanxue Yu
- Chinese Academy of Inspection and Quarantine, Beijing, 100176, China
| | - Jun Wang
- Chinese Academy of Inspection and Quarantine, Beijing, 100176, China
| | - Yuping Wu
- Chinese Academy of Inspection and Quarantine, Beijing, 100176, China.
| | - Shuifang Zhu
- Chinese Academy of Inspection and Quarantine, Beijing, 100176, China.
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14
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Liew JW, Fong MY, Lau YL. Quantitative real-time PCR analysis of Anopheles dirus TEP1 and NOS during Plasmodium berghei infection, using three reference genes. PeerJ 2017; 5:e3577. [PMID: 28761783 PMCID: PMC5533154 DOI: 10.7717/peerj.3577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 06/23/2017] [Indexed: 01/12/2023] Open
Abstract
Quantitative reverse transcription PCR (qRT-PCR) has been an integral part of characterizing the immunity of Anopheles mosquitoes towards Plasmodium invasion. Two anti-Plasmodium factors of Anopheles, thioester-containing protein 1 (TEP1) and nitric oxide synthase (NOS), play a role in the refractoriness of Anopheles towards Plasmodium infection and are generally expressed during infection. However, these are less studied in Anopheles dirus, a dominant malaria vector in Southeast Asia. Furthermore, most studies used a single reference gene for normalization during gene expression analysis without proper validation. This may lead to erroneous quantification of expression levels. Therefore, the present study characterized and investigated the expression profiles of TEP1 and NOS of Anopheles dirus during P. berghei infection. Prior to that, the elongation factor 1-alpha (EF1), actin 1 (Act) and ribosomal protein S7 (S7) genes were validated for their suitability as a set of reference genes. TEP1 and NOS expressions in An. dirus were found to be significantly induced after P. berghei infection.
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Affiliation(s)
- Jonathan W.K. Liew
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
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15
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Dengue virus detection in Aedes aegypti larvae and pupae collected in rural areas of Anapoima, Cundinamarca, Colombia. BIOMEDICA 2017; 37:193-200. [PMID: 29161491 DOI: 10.7705/biomedica.v37i0.3584] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 05/16/2017] [Indexed: 11/21/2022]
Abstract
INTRODUCTION There is a high incidence and prevalence of dengue in the department of Cundinamarca, and recently Aedes aegypti, the main vector of dengue virus (DENV), was detected in some of its rural areas. OBJECTIVE To evaluate viral transovarial transmission in larvae and pupae collected in rural areas of the municipality of Anapoima, Cundinamarca. MATERIALS AND METHODS Live larvae and pupae were collected from 53 homes and later they were taken to the laboratory in Anapoima, where they were classified, pooled and frozen. In Bogotá, they were homogenized, RNA was extracted with Trizol™, and RT-PCR and conventional PCR were performed. The amplified products were analyzed on 2% agarose gels. RESULTS In 54.7% of the houses we found A. aegypti in immature stages, and DENV-1 was the most frequent serotype. However, the simultaneous presence of DENV 1 and 2, DENV 1 and 3, DENV 1 and 4, and DENV 1, 2 and 3 serotypes was detected in some pools. CONCLUSION The results confirmed the natural vertical transmission of the virus in the rural area under study. These findings confirmed the vector capacity of A. aegypti, and partly explains the persistence of the virus in the region and the possibility of transmission by the vector during adulthood without having ingested infected blood. This situation increases the risk of DENV infection in Colombia and the need for prevention and control programs in all areas where the mosquito is present.
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16
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Mishra P, Furey C, Balaraman V, Fraser MJ. Antiviral Hammerhead Ribozymes Are Effective for Developing Transgenic Suppression of Chikungunya Virus in Aedes aegypti Mosquitoes. Viruses 2016; 8:v8060163. [PMID: 27294950 PMCID: PMC4926183 DOI: 10.3390/v8060163] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 05/24/2016] [Accepted: 05/25/2016] [Indexed: 12/18/2022] Open
Abstract
The chikungunya virus (CHIKV) is an emerging pathogen with widespread distribution in regions of Africa, India, and Asia that threatens to spread into temperate climates with the introduction of its major vector, Aedes albopictus. CHIKV causes a disease frequently misdiagnosed as dengue fever, with potentially life-threatening symptoms that can result in a longer-term debilitating arthritis. The increasing risk of spread from endemic regions via human travel and commerce and the current absence of a vaccine put a significant proportion of the world population at risk for this disease. In this study we designed and tested hammerhead ribozymes (hRzs) targeting CHIKV structural protein genes of the RNA genome as potential antivirals both at the cellular and in vivo level. We employed the CHIKV strain 181/25, which exhibits similar infectivity rates in both Vero cell cultures and mosquitoes. Virus suppression assay performed on transformed Vero cell clones of all seven hRzs demonstrated that all are effective at inhibiting CHIKV in Vero cells, with hRz #9 and #14 being the most effective. piggyBac transformation vectors were constructed using the Ae. aegypti t-RNAval Pol III promoted hRz #9 and #14 effector genes to establish a total of nine unique transgenic Higgs White Eye (HWE) Ae. aegypti lines. Following confirmation of transgene expression by real-time polymerase chain reaction (RT-PCR), comparative TCID50-IFA analysis, in situ Immuno-fluorescent Assays (IFA) and analysis of salivary CHIKV titers demonstrated effective suppression of virus replication at 7 dpi in heterozygous females of each of these transgenic lines compared with control HWE mosquitoes. This report provides a proof that appropriately engineered hRzs are powerful antiviral effector genes suitable for population replacement strategies
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Affiliation(s)
- Priya Mishra
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, P.O. Box 369, Notre Dame, IN 46556, USA.
| | - Colleen Furey
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, P.O. Box 369, Notre Dame, IN 46556, USA.
| | - Velmurugan Balaraman
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, P.O. Box 369, Notre Dame, IN 46556, USA.
| | - Malcolm J Fraser
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, P.O. Box 369, Notre Dame, IN 46556, USA.
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17
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Pérez-Castro R, Castellanos JE, Olano VA, Matiz MI, Jaramillo JF, Vargas SL, Sarmiento DM, Stenström TA, Overgaard HJ. Detection of all four dengue serotypes in Aedes aegypti female mosquitoes collected in a rural area in Colombia. Mem Inst Oswaldo Cruz 2016; 111:233-40. [PMID: 27074252 PMCID: PMC4830112 DOI: 10.1590/0074-02760150363] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 03/08/2016] [Indexed: 01/28/2023] Open
Abstract
The Aedes aegypti vector for dengue virus (DENV) has been reported in urban and periurban areas. The information about DENV circulation in mosquitoes in Colombian rural areas is limited, so we aimed to evaluate the presence of DENV in Ae. aegypti females caught in rural locations of two Colombian municipalities, Anapoima and La Mesa. Mosquitoes from 497 rural households in 44 different rural settlements were collected. Pools of about 20 Ae. aegypti females were processed for DENV serotype detection. DENV in mosquitoes was detected in 74% of the analysed settlements with a pool positivity rate of 62%. The estimated individual mosquito infection rate was 4.12% and the minimum infection rate was 33.3/1,000 mosquitoes. All four serotypes were detected; the most frequent being DENV-2 (50%) and DENV-1 (35%). Two-three serotypes were detected simultaneously in separate pools. This is the first report on the co-occurrence of natural DENV infection of mosquitoes in Colombian rural areas. The findings are important for understanding dengue transmission and planning control strategies. A potential latent virus reservoir in rural areas could spill over to urban areas during population movements. Detecting DENV in wild-caught adult mosquitoes should be included in the development of dengue epidemic forecasting models.
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Affiliation(s)
| | | | - Víctor A Olano
- Universidad El Bosque, Instituto de Salud y Ambiente, Bogotá,
Colombia
| | - María Inés Matiz
- Universidad El Bosque, Instituto de Salud y Ambiente, Bogotá,
Colombia
| | - Juan F Jaramillo
- Universidad El Bosque, Instituto de Salud y Ambiente, Bogotá,
Colombia
| | - Sandra L Vargas
- Universidad El Bosque, Instituto de Salud y Ambiente, Bogotá,
Colombia
| | - Diana M Sarmiento
- Universidad El Bosque, Instituto de Salud y Ambiente, Bogotá,
Colombia
| | - Thor Axel Stenström
- Durban University of Technology, South African Research Chair
Initiative, Durban, South Africa
| | - Hans J Overgaard
- Norwegian University of Life Sciences, Department of Mathematical and
Technological Sciences, Ås, Norway
- Kasetsart University, Department of Entomology, Bangkok, Thailand
- Institut de Recherche pour le Développement, Maladies Infectieuses et
Vecteurs Écologie, Génétique, Évolution et Contrôle, Montpellier, France
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18
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Onyango MG, Beebe NW, Gopurenko D, Bellis G, Nicholas A, Ogugo M, Djikeng A, Kemp S, Walker PJ, Duchemin JB. Assessment of population genetic structure in the arbovirus vector midge, Culicoides brevitarsis (Diptera: Ceratopogonidae), using multi-locus DNA microsatellites. Vet Res 2015; 231:39-58. [PMID: 26408175 DOI: 10.1007/978-3-319-20825-1_2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
Abstract
Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges (Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant (P < 0.05) population genetic subdivision was observed between all paired regions, though the highest levels of genetic sub-division involved pair-wise tests with PNG (PNG vs. Australia (FST = 0.120) and PNG vs. Timor-Leste (FST = 0.095)). Analysis of multi-locus allelic distributions using STRUCTURE identified a most probable two-cluster population model, which separated PNG specimens from a cluster containing specimens from Timor-Leste and Australia. The source of incursions of this species in Australia is more likely to be Timor-Leste than PNG. Future incursions of BTV positive C. brevitarsis into Australia may be genetically identified to their source populations using these microsatellite loci. The vector's panmictic genetic structure within Australia cannot explain the differential geographic distribution of BTV serotypes.
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Affiliation(s)
- Maria G Onyango
- CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia. .,School of Medicine, Deakin University, 75 Pidgons Road, Waurn Ponds, Victoria, 3216, Australia.
| | - Nigel W Beebe
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia. .,CSIRO Health & Biosecurity Ecosciences Precinct, 41, Boggo Road, Dutton Park, Queensland, 4102, Australia.
| | - David Gopurenko
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, PMB, Wagga Wagga, New South Wales, 2650, Australia. .,Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, New South Wales, 2678, Australia.
| | - Glenn Bellis
- Northern Australia Quarantine Strategy, 1 Pederson Road, Marrara, Northern Territory, 0812, Australia.
| | - Adrian Nicholas
- Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, New South Wales, 2678, Australia.
| | - Moses Ogugo
- International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya.
| | - Appolinaire Djikeng
- International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya. .,Biosciences eastern and central Africa - ILRI Hub (BecA-ILRI Hub), ILRI, PO Box 30709, 00100, Nairobi, Kenya.
| | - Steve Kemp
- International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya.
| | - Peter J Walker
- CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia.
| | - Jean-Bernard Duchemin
- CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia.
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19
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Onyango MG, Beebe NW, Gopurenko D, Bellis G, Nicholas A, Ogugo M, Djikeng A, Kemp S, Walker PJ, Duchemin JB. Assessment of population genetic structure in the arbovirus vector midge, Culicoides brevitarsis (Diptera: Ceratopogonidae), using multi-locus DNA microsatellites. Vet Res 2015; 46:108. [PMID: 26408175 PMCID: PMC4582633 DOI: 10.1186/s13567-015-0250-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/24/2015] [Indexed: 11/10/2022] Open
Abstract
Bluetongue virus (BTV) is a major pathogen of ruminants that is transmitted by biting midges (Culicoides spp.). Australian BTV serotypes have origins in Asia and are distributed across the continent into two distinct episystems, one in the north and another in the east. Culicoides brevitarsis is the major vector of BTV in Australia and is distributed across the entire geographic range of the virus. Here, we describe the isolation and use of DNA microsatellites and gauge their ability to determine population genetic connectivity of C. brevitarsis within Australia and with countries to the north. Eleven DNA microsatellite markers were isolated using a novel genomic enrichment method and identified as useful for genetic analyses of sampled populations in Australia, northern Papua New Guinea (PNG) and Timor-Leste. Significant (P < 0.05) population genetic subdivision was observed between all paired regions, though the highest levels of genetic sub-division involved pair-wise tests with PNG (PNG vs. Australia (FST = 0.120) and PNG vs. Timor-Leste (FST = 0.095)). Analysis of multi-locus allelic distributions using STRUCTURE identified a most probable two-cluster population model, which separated PNG specimens from a cluster containing specimens from Timor-Leste and Australia. The source of incursions of this species in Australia is more likely to be Timor-Leste than PNG. Future incursions of BTV positive C. brevitarsis into Australia may be genetically identified to their source populations using these microsatellite loci. The vector’s panmictic genetic structure within Australia cannot explain the differential geographic distribution of BTV serotypes.
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Affiliation(s)
- Maria G Onyango
- CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia. .,School of Medicine, Deakin University, 75 Pidgons Road, Waurn Ponds, Victoria, 3216, Australia.
| | - Nigel W Beebe
- School of Biological Sciences, The University of Queensland, St Lucia, Queensland, 4072, Australia. .,CSIRO Health & Biosecurity Ecosciences Precinct, 41, Boggo Road, Dutton Park, Queensland, 4102, Australia.
| | - David Gopurenko
- NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, PMB, Wagga Wagga, New South Wales, 2650, Australia. .,Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, New South Wales, 2678, Australia.
| | - Glenn Bellis
- Northern Australia Quarantine Strategy, 1 Pederson Road, Marrara, Northern Territory, 0812, Australia.
| | - Adrian Nicholas
- Graham Centre for Agricultural Innovation, Locked Bag 588, Wagga Wagga, New South Wales, 2678, Australia.
| | - Moses Ogugo
- International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya.
| | - Appolinaire Djikeng
- International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya. .,Biosciences eastern and central Africa - ILRI Hub (BecA-ILRI Hub), ILRI, PO Box 30709, 00100, Nairobi, Kenya.
| | - Steve Kemp
- International Livestock Research Institute, P.O. Box 30709, 00100, Nairobi, Kenya.
| | - Peter J Walker
- CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia.
| | - Jean-Bernard Duchemin
- CSIRO Health & Biosecurity Australian Animal Health Laboratory, 5 Portalington Road, Geelong, Victoria, 3220, Australia.
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Datta S, Gopalakrishnan R, Chatterjee S, Veer V. Phylogenetic Characterization of a Novel Insect-Specific Flavivirus Detected in a Culex Pool, Collected from Assam, India. Intervirology 2015; 58:149-54. [DOI: 10.1159/000381901] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Accepted: 03/24/2015] [Indexed: 11/19/2022] Open
Abstract
Objective: We report the phylogenetic characterization of a unique flavivirus sequence detected in a wild Culex tritaeniorhynchus mosquito pool, collected from the northeast Indian state of Assam. Methods: DNA and RNA were extracted from field-collected mosquito pools. Extracts were subjected to PCR and reverse transcriptase PCR amplification using universal and type-specific primers for direct detection of flavivirus-specific viral nucleic acids. An amplified flavivirus nonstructural protein 5 (NS5) genetic region was sequenced and BLAST searched, and phylogenetic analyses performed with reference sequences retrieved from GenBank. Results: Phylogenetic analyses revealed the sequence to be related to insect-specific flaviviruses (ISFs) of the genus Flavivirus, family Flaviviridae. Despite being related to the Palm Creek virus (PCV; an ISF very recently reported from Northern Australia), the present sequence (provisionally named Assam virus) was found to be highly divergent from PCV and other ISF sequences available in GenBank. The partial NS5 sequence analysis demonstrated low nucleotide sequence identity (66-77%) with known ISFs reported from other parts of the globe. Conclusion: Findings of this study suggest the presence of a candidate novel ISF - the first to be reported from India.
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Adelman ZN, Anderson MAE, Liu M, Zhang L, Myles KM. Sindbis virus induces the production of a novel class of endogenous siRNAs in Aedes aegypti mosquitoes. INSECT MOLECULAR BIOLOGY 2012; 21:357-68. [PMID: 22458920 PMCID: PMC3386798 DOI: 10.1111/j.1365-2583.2012.01141.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Small RNA regulatory pathways are used to control the activity of transposons, regulate gene expression and resist infecting viruses. We examined the biogenesis of mRNA-derived endogenous short-interfering RNAs (endo-siRNAs) in the disease vector mosquito Aedes aegypti. Under standard conditions, mRNA-derived endo-siRNAs were produced from the bidirectional transcription of tail-tail overlapping gene pairs. Upon infection with the alphavirus, Sindbis virus (SINV), another class of mRNA-derived endo-siRNAs was observed. Genes producing SINV-induced endo-siRNAs were not enriched for overlapping partners or nearby genes, but were enriched for transcripts with long 3' untranslated regions. Endo-siRNAs from this class derived uniformly from the entire length of the target transcript, and were found to regulate the transcript levels of the genes from which they were derived. Strand-specific quantitative PCR experiments demonstrated that antisense strands of targeted mRNA genes were produced to exonic, but not intronic regions. Finally, small RNAs mapped to both sense and antisense strands of exon-exon junctions, suggesting double-stranded RNA precursors to SINV-induced endo-siRNAs may be synthesized from mature mRNA templates. These results suggest additional complexity in small RNA pathways and gene regulation in the presence of an infecting virus in disease vector mosquitoes.
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Affiliation(s)
- Z N Adelman
- Fralin Life Science Institute and Department of Entomology, Virginia Tech, Blacksburg, VA 24061, USA.
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Quito-Avila DF, Lightle D, Lee J, Martin RR. Transmission biology of Raspberry latent virus, the first aphid-borne reovirus. PHYTOPATHOLOGY 2012; 102:547-553. [PMID: 22352304 DOI: 10.1094/phyto-12-11-0331] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Raspberry latent virus (RpLV) is a newly characterized reovirus found in commercial raspberry fields in the Pacific Northwest (PNW). Thus far, all members of the plant reoviruses are transmitted in a replicative, persistent manner by several species of leafhoppers or planthoppers. After several failed attempts to transmit RpLV using leafhoppers, the large raspberry aphid, commonly found in the PNW, was tested as a vector of the virus. The virus was transmitted to new, healthy raspberry plants when inoculated with groups of at least 50 viruliferous aphids, suggesting that aphids are vectors of RpLV, albeit inefficient ones. Using absolute and relative quantification methods, it was shown that the virus titer in aphids continued to increase after the acquisition period even when aphids were serially transferred onto fresh, healthy plants on a daily basis. Transmission experiments determined that RpLV has a 6-day latent period in the aphid before it becomes transmissible; however, it was not transmitted transovarially to the next generation. To our knowledge, this is the first report of a plant reovirus transmitted by an aphid. Phylogenetic analyses showed that RpLV is related most closely to but distinct from Rice ragged stunt virus (RRSV), the type member of the genus Oryzavirus. Moreover, the conserved nucleotide termini of the genomic segments of RpLV did not match those of RRSV or other plant reoviruses, allowing us to suggest that RpLV is probably the type member of a new genus in the Reoviridae comprising aphid-transmitted reoviruses.
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Affiliation(s)
- Diego F Quito-Avila
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, USA.
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Quito-Avila DF, Martin RR. Real-time RT-PCR for detection of Raspberry bushy dwarf virus, Raspberry leaf mottle virus and characterizing synergistic interactions in mixed infections. J Virol Methods 2011; 179:38-44. [PMID: 21968094 DOI: 10.1016/j.jviromet.2011.09.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/14/2011] [Accepted: 09/19/2011] [Indexed: 10/17/2022]
Abstract
Two TaqMan-based real-time One-Step RT-PCR assays were developed for the rapid and efficient detection of Raspberry bushy dwarf virus (RBDV) and Raspberry leaf mottle virus (RLMV), two of the most common raspberry viruses in North America and Europe. The primers and probes were designed from conserved fragments of the polymerase region of each virus and were effective for the detection of different isolates tested in this study. The RBDV assay amplified a 94bp amplicon and was able to detect as few as 30 viral copies. Whereas the RLMV assay amplified a 180bp amplicon and detected as few as 300 viral copies from plant and aphid RNA extracts. Both assays were significantly more sensitive than their corresponding conventional RT-PCR methods. The sensitivity of the RLMV assay was also tested on single aphids after a fixed acquisition access period (AAP). In addition, the assays revealed a novel synergistic interaction between the two viruses, where the concentration of RBDV was enhanced ∼400-fold when it occurred in combination with RLMV compared to its concentration in single infections. The significance of this finding and the importance of the development of real-time RT-PCR assays for the detection of RBDV and RLMV are discussed.
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Affiliation(s)
- Diego F Quito-Avila
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA.
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Saiyasombat R, Bolling BG, Brault AC, Bartholomay LC, Blitvich BJ. Evidence of efficient transovarial transmission of Culex flavivirus by Culex pipiens (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2011; 48:1031-1038. [PMID: 21936322 DOI: 10.1603/me11043] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
This study determined the transovarial transmission (TOT) potential and tissue tropisms of Culex flavivirus (CxFV), an insect-specific flavivirus, in Culex pipiens (L.). Several hundred mosquito egg rafts were collected in the field, transferred to the insectaries, reared to the fourth larval instar, and identified using morphological characteristics. Cx. pipiens were reared to adults, allowed to oviposit in individual containers, and tested for CxFV RNA by reverse transcription-polymerase chain reaction (RT-PCR) and nucleotide sequencing. Eighteen CxFV RNA-positive females were identified from 26 females that oviposited viable egg rafts. Thirty F1 adults from each positive female were individually tested by RT-PCR for CxFV RNA. Viral RNA was detected in 526 of 540 progeny, and thus, the filial infection rate was 97.4%. Because all 18 positive females produced infected offspring, the TOT prevalence was 100%. These data indicated that efficient TOT of CxFV occurs in nature. To define the tissue tropisms of CxFV, different tissues (salivary glands, ovaries, testes, head, fat bodies, and midguts) were removed from the remainder of the F1 and tested by RT-PCR for CxFV RNA. Viral RNA was detected in all tissues. Additionally, uninfected laboratory-colonized Cx. pipiens were infected with CxFV by needle inoculation, and ovaries were collected at 4, 6, 8, and 12 d postinoculation and tested for CxFV RNA by RT-PCR. Viral RNA was detected at all time points, demonstrating that CxFV infects the ovaries as early as 4 d postinoculation. Surprisingly, however, we were unable to demonstrate transovarial transmission despite the presence of viral RNA in the ovaries. Nevertheless, the experiments performed with field-infected Cx. pipiens demonstrate that TOT is an efficient mechanism by which CxFV is maintained in mosquitoes in nature.
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Affiliation(s)
- Rungrat Saiyasombat
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA
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