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Kalogianni AI, Bouzalas I, Bossis I, Gelasakis AI. A Longitudinal Cohort Study of Risk Factors Associated with Small Ruminant Lentivirus Seropositivity in Intensively Reared Dairy Ewes in Greece. Pathogens 2023; 12:1200. [PMID: 37887716 PMCID: PMC10609844 DOI: 10.3390/pathogens12101200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/28/2023] Open
Abstract
A two-year longitudinal cohort study was conducted on a total of 407 purebred Chios and Lacaune ewes from four intensive dairy sheep farms to assess potential risk factors for small ruminant lentiviruses (SRLVs) seropositivity. Ewes were serologically tested semiannually at pre-mating and pre-lambing, and their age, breed, and body condition score (BCS) were recorded. Εwes were categorized as constantly seronegative, constantly seropositive, seroconverted, seroreverted, or animals with an intermittent presence of antibodies. Mixed binary logistic regression models were used to estimate the adjusted relative risks of the studied risk factors for (i) the individual ewes' seropositivity, (ii) the manifestation of specific serological patterns, and (iii) the occurrence of seroconversion and seroreversion incidents. Increased age was associated with seropositivity and constantly seropositive status (p < 0.001 in both cases). On the other hand, age was negatively associated with constantly seronegative pattern, seroconversion incident, and the intermittent presence of antibodies (p < 0.05 in all cases). Moreover, breed was recognized as a risk factor: Lacaune ewes demonstrated increased seropositivity, whereas Chios ewes were more likely to demonstrate an intermittent presence of antibodies (p < 0.01 in both cases). Seropositive status (p < 0.001), seropositivity in animals with an intermittent presence of antibodies (p = 0.001), and seroconversion incidents (p < 0.001) were significantly increased at pre-lambing compared to pre-mating. The risk factors recognized in our study contribute to a better understanding of SRLVs epidemiology and the evidence-based designation of SRLVs' control programs in intensive dairy sheep farms in Greece.
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Affiliation(s)
- Aphrodite I Kalogianni
- Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, 11855 Athens, Greece
| | - Ilias Bouzalas
- Hellenic Agricultural Organization-DEMETER, Veterinary Research Institute, Campus of Thermi, 57001 Thessaloniki, Greece
| | - Ioannis Bossis
- Department of Agricultural Sciences, School of Agriculture, Forestry and Natural Resources, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Athanasios I Gelasakis
- Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, 11855 Athens, Greece
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Kalogianni AI, Bouzalas I, Bossis I, Gelasakis AI. Seroepidemiology of Maedi-Visna in Intensively Reared Dairy Sheep: A Two-Year Prospective Study. Animals (Basel) 2023; 13:2273. [PMID: 37508051 PMCID: PMC10375974 DOI: 10.3390/ani13142273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 07/05/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
The objective of this study is to prospectively evaluate the seroepidemiology of maedi-visna (MV) infections in intensively reared dairy sheep. A total of 407 purebred Chios and Lacaune ewes from four farms were surveyed for two consecutive years and were serologically tested semiannually with an indirect ELISA at pre-mating and pre-lambing. The farms' structure and management practices were similar and animal traits (age, breed, and production stage) were recorded. Based on the serological status, morbidity frequency measures were estimated, and ewes were categorized as constantly seronegative, constantly seropositive, seroconverted, seroreverted, or as animals with an intermittent presence of antibodies. During the study, period seroprevalence, incidence rate, and cumulative incidence were 84.8%, 33.6 new cases per 100 sheep-semesters, and 64.2%. Point-seroprevalence ranged from 48.5% to 96.0% among the studied farms and sampling occasions, and they increased by age. Increased morbidity frequency measures indicate the significance of horizontal transmission in intensive dairy sheep farms. A remarkable percentage of infected animals seroreverted (8.1%) or presented an intermittent presence of antibodies (10.3%) during the study, confirming the risk of misdiagnosis in cross-sectional studies and in the currently implemented testing and elimination programs. The serological patterns observed in our study need to be considered when studying MV epidemiology and for the designing of efficient MV elimination programs.
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Affiliation(s)
- Aphrodite I Kalogianni
- Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, 11855 Athens, Greece
| | - Ilias Bouzalas
- Veterinary Research Institute, Hellenic Agricultural Organization-DEMETER, Campus of Thermi, 57001 Thessaloniki, Greece
| | - Ioannis Bossis
- Department of Agricultural Sciences, School of Agriculture, Forestry and Natural Resources, University Campus, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Athanasios I Gelasakis
- Department of Animal Science, School of Animal Biosciences, Agricultural University of Athens, 11855 Athens, Greece
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3
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Jacob-Ferreira J, Coelho AC, Grau Vila A, Lacasta D, Quintas H. Small Ruminant Lentivirus Infection in Sheep and Goats in North Portugal: Seroprevalence and Risk Factors. Pathogens 2023; 12:829. [PMID: 37375519 DOI: 10.3390/pathogens12060829] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/07/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Small ruminant lentiviruses (SRLVs) are transmitted among ovine and caprine species. This disease is a severe problem for small ruminant production, not only for animals' well-being but also for flocks' efficiency. The main aim of this research was to quantify the seroprevalence and associated risk factors for SRLV infection in the northern region of Portugal. Samples were collected from a total of 150 flocks, of which 129 (86.0%; 95% CI: 80.67%-91.33%) had at least one seropositive animal. Out of 2607 individual blood samples, 1074 (41.2%) were positive for SRLVs. Risk factors associated with SRLV infection were species (caprine), age (>2 years old), flock size (>100 animals), production system (intensive), food production system (milk), type of activity (professional), participation in livestock competitions (yes), replacement young ewe bought (yes), and natural feeding management (yes). This knowledge empowers the implementation of effective preventive measures. Overall, biosecurity measures should be promoted and implemented with the main aim of reducing viral transmission and reducing the prevalence of this disease. We recognise that government authorities should promote and audit voluntary control and eradication programs in small ruminant flocks in the region studied.
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Affiliation(s)
- João Jacob-Ferreira
- Animal and Veterinary Research Centre, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal
- Mountain Research Center (CIMO), Polytechnic Institute of Bragança (IPB), Campus de Santa Apolónia, 5300-253 Bragança, Portugal
| | - Ana Cláudia Coelho
- Animal and Veterinary Research Centre, University of Trás-os-Montes and Alto Douro (UTAD), 5000-801 Vila Real, Portugal
| | - Ana Grau Vila
- Servicio de Sanidad Animal, Dirección General de Producción Agropecuaria e Infraestructuras Agrarias, Consejería de Agricultura y Ganadería, Junta de Castilla y León, 47014 Valladolid, Spain
| | - Delia Lacasta
- Animal Pathology Department, Instituto Agroalimentario de Aragón-IA2, Universidad de Zaragoza-CITA, Veterinary Faculty of Zaragoza C/Miguel Servet 177, 50013 Zaragoza, Spain
| | - Hélder Quintas
- Mountain Research Center (CIMO), Polytechnic Institute of Bragança (IPB), Campus de Santa Apolónia, 5300-253 Bragança, Portugal
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Jones S, McKay H, Eden L, Bollard N, Dunham S, Davies P, Tarlinton R. Clearance of Maedi-visna infection in a longitudinal study of naturally infected rams is associated with homozygosity for the TMEM154 resistance allele. J Med Microbiol 2022; 71. [PMID: 35144720 PMCID: PMC8941955 DOI: 10.1099/jmm.0.001506] [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] [Indexed: 12/03/2022] Open
Abstract
Maedi-visna (MV) is a lentiviral disease of sheep responsible for severe production losses in affected flocks. There are no vaccination or treatment options with control reliant on test and cull strategies. The most common diagnostic methods used at present are combination ELISAs for Gag and Env proteins with virus variability making PCR diagnostics still largely an experimental tool. To assess variability in viral loads and diagnostic tests results, serology, DNA and RNA viral loads were measured in the blood of 12 naturally infected rams repeatedly blood sampled over 16 months. Six animals tested negative in one or more tests at one or more time points and would have been missed on screening programmes reliant on one test method or a single time point. In addition the one animal homozygous for the ‘K’ allele of the TMEM154 E35K SNP maintained very low viral loads in all assays and apparently cleared infection to below detectable limits at the final time point it was sampled. This adds crucial data to the strong epidemiological evidence that this locus represents a genuine resistance marker for MV infection and is a strong candidate for selective breeding of sheep for resistance to disease.
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Affiliation(s)
- Scott Jones
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.,Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Heather McKay
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.,Three Valleys Veterinary, 107 Kesh Road, Irvinestown, Enniskillen BT94FX, UK
| | - Laura Eden
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.,Bishopton Veterinary Group, Mill Farm, Studley Road, Ripon, North Yorkshire, HG4 2QR, UK
| | - Nicola Bollard
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Stephen Dunham
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
| | - Peers Davies
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK.,Department of Livestock and One Health, University of Liverpool, Liverpool, CH64 7TE, UK
| | - Rachael Tarlinton
- School of Veterinary Medicine and Science, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK
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Aalberts M, Peterson K, Moll L, Vellema P, van Maanen C. Evaluation of five SRLV ELISAs for fitness for purpose in sheep and goat accreditation schemes in the Netherlands. Small Rumin Res 2021. [DOI: 10.1016/j.smallrumres.2021.106452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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de Miguel R, Arrieta M, Rodríguez-Largo A, Echeverría I, Resendiz R, Pérez E, Ruiz H, Pérez M, de Andrés D, Reina R, de Blas I, Luján L. Worldwide Prevalence of Small Ruminant Lentiviruses in Sheep: A Systematic Review and Meta-Analysis. Animals (Basel) 2021; 11:784. [PMID: 33799908 PMCID: PMC8000744 DOI: 10.3390/ani11030784] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 03/04/2021] [Accepted: 03/08/2021] [Indexed: 11/16/2022] Open
Abstract
Small Ruminant Lentiviruses (SRLV) are highly prevalent retroviruses with significant genetic diversity and antigenic heterogeneity that cause a progressive wasting disease of sheep called Maedi-visna. This work provides a systematic review and meta-analysis of the last 40 years (1981-2020) of scientific publications on SRLV individual and flock prevalence. Fifty-eight publications and 314 studies were included. Most articles used a single diagnostic test to estimate prevalence (77.6%), whereas articles using three or more tests were scarce (6.9%). Serological tests are more frequently used than direct methods and ELISA has progressively replaced AGID over the last decades. SRLV infection in sheep is widespread across the world, with Europe showing the highest individual prevalence (40.9%) and being the geographical area in which most studies have been performed. Africa, Asia, and North America show values between 16.7% to 21.8% at the individual level. South and Central America show the lowest individual SRLV prevalence (1.7%). There was a strong positive correlation between individual and flock prevalence (ρ = 0.728; p ≤ 0.001). Despite the global importance of small ruminants, the coverage of knowledge on SRLV prevalence is patchy and inconsistent. There is a lack of a gold standard method and a defined sampling strategy among countries and continents.
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Affiliation(s)
- Ricardo de Miguel
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
| | - Marta Arrieta
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
| | - Ana Rodríguez-Largo
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
| | - Irache Echeverría
- Institute of Agrobiotechnology, CSIC-Government of Navarra, 31192 Mutilva, Spain; (I.E.); (D.d.A.); (R.R.)
| | - Raúl Resendiz
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
| | - Estela Pérez
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
| | - Héctor Ruiz
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
| | - Marta Pérez
- Department of Anatomy, Embriology and Genetics, University of Zaragoza, 50013 Zaragoza, Spain;
- Instituto Universitario de Investigación Mixto Agroalimentario de Aragón, University of Zaragoza, 50013 Zaragoza, Spain
| | - Damián de Andrés
- Institute of Agrobiotechnology, CSIC-Government of Navarra, 31192 Mutilva, Spain; (I.E.); (D.d.A.); (R.R.)
| | - Ramsés Reina
- Institute of Agrobiotechnology, CSIC-Government of Navarra, 31192 Mutilva, Spain; (I.E.); (D.d.A.); (R.R.)
| | - Ignacio de Blas
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
- Instituto Universitario de Investigación Mixto Agroalimentario de Aragón, University of Zaragoza, 50013 Zaragoza, Spain
| | - Lluís Luján
- Department of Animal Pathology, University of Zaragoza, 50013 Zaragoza, Spain; (R.d.M.); (M.A.); (A.R.-L.); (R.R.); (E.P.); (H.R.); (I.d.B.)
- Instituto Universitario de Investigación Mixto Agroalimentario de Aragón, University of Zaragoza, 50013 Zaragoza, Spain
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Ramírez H, Echeverría I, Benito AA, Glaria I, Benavides J, Pérez V, de Andrés D, Reina R. Accurate Diagnosis of Small Ruminant Lentivirus Infection Is Needed for Selection of Resistant Sheep through TMEM154 E35K Genotyping. Pathogens 2021. [DOI: https://doi.org/10.3390/pathogens10010083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Small ruminant lentiviruses (SRLV) cause an incurable multiorganic disease widely spread in sheep and goats that disturbs animal welfare and production. In the absence of a vaccine, control measures have been traditionally based on early diagnosis and breeding with virus-inactivated colostrum with segregation of seropositive animals. However, antigenic heterogeneity, poor antibody production due to low viral load, and single strain design of most available ELISA, pose a threat to SRLV diagnosis. Genome-wide association studies have described TMEM154 E35K polymorphism as a good genetic marker for selection of resistant animals in some American and European breeds. In this study, a multitargeted serological and virological screening of more than 500 animals from four different breeds (latxa, raza Navarra, assaf, and churra) attending to SRLV infection status was performed. Then, animals were genotyped to characterize TMEM154 E35K polymorphism. ELISA procedures, individually considered, only identified a proportion of the seropositive animals, and PCR detected a fraction of seronegative animals, globally offering different animal classifications according to SRLV infection status. TMEM154 allele frequency differed substantially among breeds and a positive association between seroprevalence and TMEM154 genotype was found only in one breed. Selection based on TMEM154 may be suitable for specific ovine breeds or SRLV strains, however generalization to the whole SRLV genetic spectrum, ovine breeds, or epidemiological situation may need further validation.
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Ramírez H, Echeverría I, Benito AA, Glaria I, Benavides J, Pérez V, de Andrés D, Reina R. Accurate Diagnosis of Small Ruminant Lentivirus Infection Is Needed for Selection of Resistant Sheep through TMEM154 E35K Genotyping. Pathogens 2021; 10:pathogens10010083. [PMID: 33478070 PMCID: PMC7835874 DOI: 10.3390/pathogens10010083] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 01/05/2021] [Accepted: 01/13/2021] [Indexed: 02/05/2023] Open
Abstract
Small ruminant lentiviruses (SRLV) cause an incurable multiorganic disease widely spread in sheep and goats that disturbs animal welfare and production. In the absence of a vaccine, control measures have been traditionally based on early diagnosis and breeding with virus-inactivated colostrum with segregation of seropositive animals. However, antigenic heterogeneity, poor antibody production due to low viral load, and single strain design of most available ELISA, pose a threat to SRLV diagnosis. Genome-wide association studies have described TMEM154 E35K polymorphism as a good genetic marker for selection of resistant animals in some American and European breeds. In this study, a multitargeted serological and virological screening of more than 500 animals from four different breeds (latxa, raza Navarra, assaf, and churra) attending to SRLV infection status was performed. Then, animals were genotyped to characterize TMEM154 E35K polymorphism. ELISA procedures, individually considered, only identified a proportion of the seropositive animals, and PCR detected a fraction of seronegative animals, globally offering different animal classifications according to SRLV infection status. TMEM154 allele frequency differed substantially among breeds and a positive association between seroprevalence and TMEM154 genotype was found only in one breed. Selection based on TMEM154 may be suitable for specific ovine breeds or SRLV strains, however generalization to the whole SRLV genetic spectrum, ovine breeds, or epidemiological situation may need further validation.
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Affiliation(s)
- Hugo Ramírez
- Virology, Genetics and Molecular Biology Laboratory, Faculty of Higher Education, Cuautitlan, Veterinary Medicine, Campus 4, National Autonomous University of Mexico, Km. 2.5 Carretera Cuautitlán-Teoloyucan, San Sebastián Xhala, Cuautitlán Izcalli Estado de México C.P. 54714, Mexico;
| | - Irache Echeverría
- Animal Health Department, Institute of Agrobiotechnology (IdAB), CSIC-Government of Navarra, 31192 Navarra, Spain; (I.E.); (I.G.); (D.d.A.)
| | - Alfredo A. Benito
- Molecular and Cell Biology Department, EXOPOL SL, 50840 Zaragoza, Spain;
| | - Idoia Glaria
- Animal Health Department, Institute of Agrobiotechnology (IdAB), CSIC-Government of Navarra, 31192 Navarra, Spain; (I.E.); (I.G.); (D.d.A.)
| | - Julio Benavides
- Mountain Livestock Institute (IGM), CSIC-University of León, 24346 León, Spain;
| | - Valentín Pérez
- Department of Animal Health, University of León, 24071 León, Spain;
| | - Damián de Andrés
- Animal Health Department, Institute of Agrobiotechnology (IdAB), CSIC-Government of Navarra, 31192 Navarra, Spain; (I.E.); (I.G.); (D.d.A.)
| | - Ramsés Reina
- Animal Health Department, Institute of Agrobiotechnology (IdAB), CSIC-Government of Navarra, 31192 Navarra, Spain; (I.E.); (I.G.); (D.d.A.)
- Correspondence: ; Tel.: +34-948-168022
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Illius AW, Lievaart-Peterson K, McNeilly TN, Savill NJ. Epidemiology and control of maedi-visna virus: Curing the flock. PLoS One 2020; 15:e0238781. [PMID: 32911525 PMCID: PMC7482963 DOI: 10.1371/journal.pone.0238781] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 08/17/2020] [Indexed: 11/25/2022] Open
Abstract
Maedi-visna (MV) is a complex lentiviral disease syndrome characterised by long immunological and clinical latencies and chronic progressive inflammatory pathology. Incurable at the individual level, it is widespread in most sheep-keeping countries, and is a cause of lost production and poor animal welfare. Culling seropositive animals is the main means of control, but it might be possible to manage virus transmission effectively if its epidemiology was better quantified. We derive a mathematical epidemiological model of the temporal distributions of seroconversion probabilities and estimate susceptibility, transmission rate and latencies in three serological datasets. We demonstrate the existence of epidemiological latency, which has not explicitly been recognised in the SRLV literaure. This time delay between infection and infectiousness apparently exceeds the delay between infection and seroconversion. Poor body condition was associated with more rapid seroconversion, but not with a higher probability of infection. We estimate transmission rates amongst housed sheep to be at about 1,000 times faster than when sheep were at grass, when transmission was negligible. Maternal transmission has only a small role in transmission, because lambs from infected ewes have a low probability of being infected directly by them, and only a small proportion of lambs need be retained to maintain flock size. Our results show that MV is overwhelmingly a disease of housing, where sheep are kept in close proximity. Prevalence of MV is likely to double each year from an initial low incidence in housed flocks penned in typically-sized groups of sheep (c. 50) for even a few days per year. Ewes kept entirely at grass are unlikely to experience transmission frequently enough for MV to persist, and pre-existing infection should die out as older ewes are replaced, thereby essentially curing the flock.
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Affiliation(s)
- Andrew W Illius
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland
| | | | - Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Penicuik, Midlothian, Scotland
| | - Nicholas J Savill
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, Scotland
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Kalogianni AI, Bossis I, Ekateriniadou LV, Gelasakis AI. Etiology, Epizootiology and Control of Maedi-Visna in Dairy Sheep: A Review. Animals (Basel) 2020; 10:E616. [PMID: 32260101 PMCID: PMC7222820 DOI: 10.3390/ani10040616] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 03/27/2020] [Accepted: 03/31/2020] [Indexed: 01/04/2023] Open
Abstract
Maedi-visna (MV) in sheep is caused by maedi-visna virus (MVV), a small ruminant lentivirus (SRLV) that causes chronic infection and inflammatory lesions in infected animals. Pneumonia and mastitis are its predominant clinical manifestations, and the tissues infected by MVV are mainly the lungs, the mammary gland, the nervous system and the joints. MV has a worldwide distribution with distinct MVV transmission patterns depending on circulating strains and regionally applied control/eradication schemes. Nevertheless, the prevalence rate of MV universally increases. Currently, gaps in understanding the epizootiology of MV, the continuous mutation of existing and the emergence of new small ruminant lentiviruses (SRLVs) strains, lack of an effective detection protocol and the inefficiency of currently applied preventive measures render elimination of MV an unrealistic target. Therefore, modifications on the existing MV surveillance and control schemes on an evidentiary basis are necessary. Updated control schemes require the development of diagnostic protocols for the early and definitive diagnosis of MVV infections. The objectives of this review are to summarize the current knowledge in the epizootiology and control of MV in dairy sheep, to describe the research framework and to cover existing gaps in understanding future challenges regarding MV.
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Affiliation(s)
- Aphrodite I Kalogianni
- Laboratory of Anatomy and Physiology of Farm Animals, Department of Animal Science, Agricultural University of Athens (AUA), Iera Odos 75 str., 11855 Athens, Greece
| | - Ioannis Bossis
- Laboratory of Anatomy and Physiology of Farm Animals, Department of Animal Science, Agricultural University of Athens (AUA), Iera Odos 75 str., 11855 Athens, Greece
| | | | - Athanasios I Gelasakis
- Laboratory of Anatomy and Physiology of Farm Animals, Department of Animal Science, Agricultural University of Athens (AUA), Iera Odos 75 str., 11855 Athens, Greece
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12
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Gayo E, Polledo L, Magalde A, Balseiro A, García Iglesias MJ, Pérez Martínez C, Preziuso S, Rossi G, García Marín JF. Characterization of minimal lesions related to the presence of visna/maedi virus in the mammary gland and milk of dairy sheep. BMC Vet Res 2019; 15:109. [PMID: 30967151 PMCID: PMC6456970 DOI: 10.1186/s12917-019-1855-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 03/27/2019] [Indexed: 11/30/2022] Open
Abstract
Background In order to characterize the complete range of lesions, especially minimal, affecting mammary gland and viral antigen distribution and target cells using immunohistochemistry in naturally Visna/maedi (VM) 84 infected sheep were studied, forty-four from flocks with clinical cases (A) and 35 randomly sampled from two abattoirs (B) together with five negative controls (C). An immunocytochemistry technique was developed and further milk samples (n = 39) were used to study viral excretion, carrier cells and the role of milk and colostrum in the transmission of the disease. Results All sheep from group C and three sheep from group B were negative to VM in tissue sections by histopathology, immunohistochemistry and PCR, and also in serum using ELISA. Several degrees of CD3 + lymphocytic interstitial mastitis were observed in groups A and B: minimal (+) n = 26 sheep; moderate (++), n = 32 and severe (+++), n = 12. No differences in lesion distribution were observed between groups A and B. Viral presence was confirmed by immunohistochemistry using two different antibodies and/or PCR in every tissue with lesions while serology was negative in six sheep with lesions. Two milk samples taken from milk tanks from two flocks from group A and fourteen milk samples from 29 infected sheep from group B were positive to VM (most of them from animals with moderate and severe lesions). Positivity was only found in macrophages, even in focal and minimal lesions, while no positivity was observed in epithelial or any other cells in either tissue and milk samples. Conclusions This new observation of the minimal lesions described in this work increased the prevalence of VM lesions in mammary gland up to 90.9% and VM should be considered as a differential diagnosis when minimal interstitial lesions are detected. A high prevalence of VM was observed in intensive milk-producing sheep, ELISA serology did not detect as positivity all infected animals, while histology, IHC or PCR showed higher sensitivity. The cytological technique developed was very useful in milk-cell studies using hematoxylin and eosin and immunocytochemistry. Viral detection in milk samples (16/39) confirms a potential but limited role of milk/colostrum in viral transmission. Electronic supplementary material The online version of this article (10.1186/s12917-019-1855-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- E Gayo
- Veterinary Pathology Unit, School of Veterinary Medicine, University of León, León, Spain.
| | | | - A Magalde
- Veterinary Pathology Unit, School of Veterinary Medicine, University of León, León, Spain
| | | | - M J García Iglesias
- Veterinary Pathology Unit, School of Veterinary Medicine, University of León, León, Spain
| | - C Pérez Martínez
- Veterinary Pathology Unit, School of Veterinary Medicine, University of León, León, Spain
| | - S Preziuso
- School of Bioscences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - G Rossi
- School of Bioscences and Veterinary Medicine, University of Camerino, Camerino, Italy
| | - J F García Marín
- Veterinary Pathology Unit, School of Veterinary Medicine, University of León, León, Spain
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Michiels R, Van Mael E, Quinet C, Adjadj NR, Cay AB, De Regge N. Comparative Analysis of Different Serological and Molecular Tests for the Detection of Small Ruminant Lentiviruses (SRLVs) in Belgian Sheep and Goats. Viruses 2018; 10:v10120696. [PMID: 30544780 PMCID: PMC6316478 DOI: 10.3390/v10120696] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 11/23/2018] [Accepted: 12/05/2018] [Indexed: 12/31/2022] Open
Abstract
Countries rely on good diagnostic tests and appropriate testing schemes to fight against economically important small ruminant lentivirus (SRLV) infections. We undertook an extensive comparative analysis of seven commercially available serological tests and one in-house real-time PCR (qPCR) detecting genotype A and B strains using a large panel of representative Belgian field samples and samples from experimentally infected sheep and goats. ELISAs generally performed well and detected seroconversion within three weeks post experimental infection. Two enzyme-linked immunosorbent assays (ELISAs) (Elitest and IDscreen® kits) showed the highest sensitivities (>96%) and specificities (>95%) in both species, and their combined use allowed to correctly identify the infection status of all animals. Individual agar gel immunodiffusion (AGIDs) kits lacked sensitivity, but interestingly, the combined use of both kits had a sensitivity and specificity of 100%. qPCRs detected SRLV infection before seroconversion at two weeks post infection and showed a specificity of 100%. Sensitivity however remained suboptimal at 85%. These results allow to propose a faster and cheaper diagnostic testing strategy for Belgium by combining a first ELISA screening, followed by confirmation of positive samples in AGID and/or a second ELISA. Since genotypes A and B strains are predominant in many countries, these results are interesting for other countries implementing SRLV control programs.
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Affiliation(s)
- Rodolphe Michiels
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium.
| | - Eva Van Mael
- Dierengezondheidszorg Vlaanderen (DGZ), Industrielaan 29, 8820 Torhout, Belgium.
| | - Christian Quinet
- Association Régionale de Santé et d'Identification Animales (ARSIA), Allée des Artisans 2, 5590 Ciney, Belgium.
| | - Nadjah Radia Adjadj
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium.
| | - Ann Brigitte Cay
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium.
| | - Nick De Regge
- Unit of Enzootic, Vector-Borne and Bee Diseases, Sciensano, Groeselenberg 99, 1180 Brussels, Belgium.
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Gayo E, Polledo L, Balseiro A, Martínez CP, García Iglesias MJ, Preziuso S, Rossi G, García Marín JF. Inflammatory Lesion Patterns in Target Organs of Visna/Maedi in Sheep and their Significance in the Pathogenesis and Diagnosis of the Infection. J Comp Pathol 2018; 159:49-56. [PMID: 29599005 DOI: 10.1016/j.jcpa.2018.01.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/05/2018] [Accepted: 01/10/2018] [Indexed: 11/27/2022]
Abstract
Ovine visna/maedi (VM) infection is characterized by the development of chronic inflammatory lesions in different organs, mainly in the lung, mammary gland and central nervous system (CNS), with either histiocytic or lymphocytic pattern predominance being described in the CNS. To help to understand the role of host immune response in the development of these patterns, 50 naturally-infected sheep and eight non-infected sheep from intensive milk-producing flocks were studied. The histological lesion patterns in the three main target organs in each sheep were characterized. Lesion severity was determined, including minimal lesions. A histiocytic pattern was observed in 23 sheep (46%), a lymphocytic inflammatory pattern in 19 sheep (38%) and a mixed inflammatory pattern in eight sheep (16%). Forty animals showed moderate or severe lesions (80%), while 10 had minimal lesions (20%). Moderate or severe lesions affected only one target organ in 20 sheep (50%), two organs in 14 sheep (35%) and all three target organs in six sheep (15%). Infection was confirmed by immunohistochemistry (IHC) using an antibody specific for p28 of VM virus/caprine arthritis and encephalitis virus and by polymerase chain reaction (PCR) in all sheep. Minimal inflammatory lesions associated with positive IHC and PCR were observed. The results suggest that the development of a predominant inflammatory pattern in different organs within the same animal may be related to the host immune response. Minimal and focal lesions, not considered previously, should be taken into account when formulating a differential diagnosis in affected sheep.
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Affiliation(s)
- E Gayo
- Pathological Anatomy Section, Animal Health Department, School of Veterinary Medicine, University of León, Spain.
| | | | | | - C Pérez Martínez
- Pathological Anatomy Section, Animal Health Department, School of Veterinary Medicine, University of León, Spain
| | - M J García Iglesias
- Pathological Anatomy Section, Animal Health Department, School of Veterinary Medicine, University of León, Spain
| | - S Preziuso
- SERIDA, Gijón, Spain; School of Biosciences and Veterinary Medicine, University of Camerino, Italy
| | - G Rossi
- SERIDA, Gijón, Spain; School of Biosciences and Veterinary Medicine, University of Camerino, Italy
| | - J F García Marín
- Pathological Anatomy Section, Animal Health Department, School of Veterinary Medicine, University of León, Spain
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15
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Michiels R, Van Mael E, Quinet C, Welby S, Cay AB, De Regge N. Seroprevalence and risk factors related to small ruminant lentivirus infections in Belgian sheep and goats. Prev Vet Med 2017; 151:13-20. [PMID: 29496101 DOI: 10.1016/j.prevetmed.2017.12.014] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 12/14/2017] [Accepted: 12/22/2017] [Indexed: 01/13/2023]
Abstract
Maedi-Visna virus (MVV) and caprine arthritis encephalitis virus (CAEV) are two prototype members of the group of small ruminant lentiviruses (SRLVs). Both result in progressive and persistent infections of sheep and goats that impact animal health and cause economic losses. In Belgium, the sheep and goat sector is small and consists mostly of hobbyist farmers keeping few animals. A voluntary control program however exists, but less than 2% of the farmers participate to the program. The current lack of SRLV seroprevalence data and knowledge on risk factors related to SRLV seropositivity in this hobbyist sector makes it difficult to evaluate the risk of SRLV transmission from non-certified to SRLV free certified farms. We performed a nationwide SRLV seroprevalence study based on a stratified sampling proportional to the number of sheep and goat holders per province. Randomly selected sheep and goat owners were invited to participate and subject to a short questionnaire to collect information about flock size, animal health condition, age, flock constitution and housing conditions. Samples were collected from maximum 7 animals per farm and tested in a commercial ELISA. In total, we received samples from 87 sheep and 76 goat farms. Sheep flocks showed an overall seroprevalence of 9% (CI 95%: 5-15) and a between-herd seroprevalence of 17% (CI 95%:11-27). Seroprevalence at animal level in goat flocks was 6% (CI 95%: 3-12) and the between-herd seroprevalence was 13% (CI 95%: 7-23). Multiple sheep and goat breeds were found SRLV seropositive. Answers provided during the questionnaire confirmed the mostly hobbyist nature of the sector and showed that more than 65% of sheep and goat farmers had never heard of the disease. The only risk factor found to be related to SRLV seroprevalence was flock size. Herds of more than 10 goats had significantly higher chance to harbor seropositive animals (OR: 4.36; CI: 1.07; 17.73). In conclusion, it was shown that participants to the SRLV free certification program are at risk for reintroduction of the disease in their herds since SRLVs are present on about 15%-20% of non-certified farms. Except from flock size, no clear risk factors were found that are helpfull to identify flocks at risk. Greater effort should be made to inform sheep and goat farmers about the existence and consequences of this disease in order to promote the voluntary control program and further reduce the disease prevalence.
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Affiliation(s)
| | - Eva Van Mael
- Dierengezondheidszorg Vlaanderen (DGZ), Torhout, Belgium
| | - Christian Quinet
- Association Regionale de Sante et d'Identification Animales (ARSIA), Ciney, Belgium
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16
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Gayo E, Polledo L, Preziuso S, Rossi G, Balseiro A, Pérez Martínez C, García Iglesias M, García Marín J. Serological ELISA results are conditioned by individual immune response in ovine maedi visna. Small Rumin Res 2017. [DOI: 10.1016/j.smallrumres.2017.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Junkuszew A, Dudko P, Bojar W, Olech M, Osiński Z, Gruszecki TM, Kania MG, Kuźmak J, Czerski G. Risk factors associated with small ruminant lentivirus infection in eastern Poland sheep flocks. Prev Vet Med 2016; 127:44-9. [PMID: 27094139 DOI: 10.1016/j.prevetmed.2016.03.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/25/2016] [Accepted: 03/17/2016] [Indexed: 10/22/2022]
Abstract
An analysis of the risk factors for ovine lentivirus infection was performed in sheep flocks located throughout the central-eastern region of Poland. Here, we report the infection details for 98 flocks with a total of 6470 ewes, 15 sheep breeds. The identification of infected animals and a review of the epidemiological status of each flock were based on an evaluation of serological tests performed on collected blood serum samples. Blood for examination was obtained from 2925 ewes of the 98 flocks under observation. Specific antibodies for Maedi Visna Virus (MVV) were detected via ELISA. Data illustrating the conditions at each sheep farm were obtained through questionnaires completed by farmers, as well as observations, measurements, and breeding records that were available. These observations were used to assess risk factors contributing to small ruminant lentivirus (SRLV) infection in sheep flocks. It was found that both sheep flock size and the type of management system had a significant effect on the increased risk of lentiviral infection. In addition, we demonstrate that there is a significant (p<0.0001) relationship between the occurrence of mastitis (OR 2.01, CI: 1.55-2.61) and diarrhea (OR 4.22, CI: 3.30-5.39) with SRLV infection in the observed sheep. Additionally, the infection rate of the animals translated directly to an impaired physical condition. Notably, the risk of infection could potentially be reduced if sheep producers are further acquainted with SRLV detection and invoke a control program based on diagnostic tests. Moreover, marketing approval should be granted for solely SRLV-seronegative animals.
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Affiliation(s)
- Andrzej Junkuszew
- Department of Small Ruminants Breeding and Agriculture Advisor, University of Life Sciences in Lublin, 20-950 Lublin, Poland.
| | - Paulina Dudko
- Department of Small Ruminants Breeding and Agriculture Advisor, University of Life Sciences in Lublin, 20-950 Lublin, Poland
| | - Wiktor Bojar
- Department of Small Ruminants Breeding and Agriculture Advisor, University of Life Sciences in Lublin, 20-950 Lublin, Poland
| | - Monika Olech
- Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Zbigniew Osiński
- Department of Hygiene of Animal Feedingstuffs, National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Tomasz M Gruszecki
- Department of Small Ruminants Breeding and Agriculture Advisor, University of Life Sciences in Lublin, 20-950 Lublin, Poland
| | - Monika Greguła Kania
- Department of Small Ruminants Breeding and Agriculture Advisor, University of Life Sciences in Lublin, 20-950 Lublin, Poland
| | - Jacek Kuźmak
- Department of Biochemistry, National Veterinary Research Institute, 24-100 Pulawy, Poland
| | - Grzegorz Czerski
- Regional Managment for Environmental Protection in Lublin, Poland
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18
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Leymaster KA, Chitko-McKown CG, Heaton MP. Incidence of infection in 39-month-old ewes with TMEM154 diplotypes "1 1," "1 3," and "3 3" after natural exposure to ovine progressive pneumonia virus. J Anim Sci 2015; 93:41-5. [PMID: 25568355 DOI: 10.2527/jas.2014-8553] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Production and well-being of sheep and goats in many countries are harmfully impacted by small ruminant lentiviruses (SRLV) that cause incurable, progressive diseases. Susceptibility to ovine progressive pneumonia virus (OPPV), the North American form of SRLV, is influenced by variants of the ovine transmembrane protein 154 gene (TMEM154). The experimental objective was to estimate additive and dominance effects of TMEM154 haplotypes 1 and 3 on susceptibility of breeding ewes to infection after natural exposure to OPPV from birth to 39 mo of age. Sires and dams were heterozygous for TMEM154 haplotypes 1 and 3, producing ewe lambs with diplotypes "1 1," "1 3," and "3 3." These lambs were raised by mature, infected dams to ensure natural, maternal exposure to OPPV. Ewe lambs (n = 108) were kept for breeding and joined an infected flock of ewes to guarantee natural, nonmaternal exposure to OPPV. Ewes were bred to lamb at 1, 2, and 3 yr of age. Serum samples were collected at breeding, 1 mo before lambing and shortly after weaning each year to monitor infection status to 39 mo of age. During the experiment, 9 of the 108 ewes died while uninfected and data collected on these ewes were not analyzed. Infection status of the remaining 99 ewes at 39 mo of age was analyzed using logistic regression procedures. Effects of ewe type of birth, ewe type of rearing, and breed type of dam were not detected (P > 0.10), and the estimated sire variance component was nil. Ewe diplotype affected infection status (P < 0.0001), as did additive (P < 0.0001) and dominance (P < 0.0022) effects. Predicted probabilities of infection for ewes with diplotypes "1 1," "1 3," and "3 3" were 0.10, 0.88, and 0.89, respectively, and confidence intervals for diplotypes "1 3" and "3 3" were distinct from "1 1." Haplotype 3 was completely dominant to haplotype 1 at 39 mo of age. The probability of infection for ewes with either diplotype "1 3" or "3 3" averaged 8.5 times that of ewes with diplotype "1 1." Diplotype "1 3" and "3 3" ewes were highly susceptible to nonmaternal transmission of OPPV, in contrast to diplotype "1 1" ewes. Therefore, the distribution of ewes with diplotypes "1 1," "1 3," and "3 3" within a flock will influence the number of infections caused by each route of transmission. Selection and mating strategies can be implemented to produce sheep that are genetically less susceptible to OPPV infection.
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Affiliation(s)
- K A Leymaster
- USDA, ARS, Roman L. Hruska US Meat Animal Research Center, Clay Center, NE 68933-0166
| | - C G Chitko-McKown
- USDA, ARS, Roman L. Hruska US Meat Animal Research Center, Clay Center, NE 68933-0166
| | - M P Heaton
- USDA, ARS, Roman L. Hruska US Meat Animal Research Center, Clay Center, NE 68933-0166
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19
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Study on Correlation of Maedi-Visna Virus (MVV) with Ovine Subclinical Mastitis in Iran. Indian J Microbiol 2013; 54:218-22. [PMID: 25320425 DOI: 10.1007/s12088-013-0440-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2013] [Accepted: 11/21/2013] [Indexed: 10/25/2022] Open
Abstract
Maedi-Visna is an important slow viral disease of sheep leading to progressive pneumonia, encephalitis and mastitis. Udder is one of the organs affected by MVV. Despite the fact that in Iran Maedi-Visna is known since 2000, to the authors' knowledge correlation of subclinical mastitis and infection with MVV has not been assayed. In this study 50 milk samples from 10 flocks in East Azerbaijan Province of Iran were tested. None of the animals exhibited any clinical signs of the disease. Forty samples were collected from CMT positive ewes and ten were taken from CMT negative ewes. Milk samples were analyzed using PCR targeting gag sequence. Presence of provirus DNA was detected in one sample from CMT negative and seven samples from CMT positive ewes. These data demonstrate that 16.5 % of sheep with subclinical mastitis were infected to MVV. Thus this virus can be considered one of the main pathogenic agents of mastitis and can be dramatically transmitted to lambs by milk.
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Leymaster KA, Chitko-McKown CG, Clawson ML, Harhay GP, Heaton MP. Effects of TMEM154 haplotypes 1 and 3 on susceptibility to ovine progressive pneumonia virus following natural exposure in sheep. J Anim Sci 2013; 91:5114-21. [PMID: 23989875 DOI: 10.2527/jas.2013-6663] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Small ruminant lentiviruses (SRLV) adversely affect production and well-being of sheep and goats throughout much of the world. The SRLV, including ovine progressive pneumonia virus (OPPV) in North America, cause lifetime infections, and management procedures to eradicate or reduce disease prevalence are costly. Variants of ovine transmembrane protein 154 gene (TMEM154) affect susceptibility to OPPV. The primary experimental objective was to estimate additive and dominance effects of TMEM154 haplotypes 1 and 3 on susceptibility to OPPV infection following natural exposure. A group of 187 trial lambs was born and raised by mature, infected ewes to ensure natural exposure to OPPV. Parents of trial lambs were heterozygous for haplotypes 1 and 3, producing lambs with diplotypes "1 1," "1 3," and "3 3." A group of 20 sentinel lambs was born and raised by mature, uninfected ewes that were diplotype "1 1." Sentinel lambs had diplotypes "1 1" and "1 3," being sired by the same set of rams as trial lambs. Trial and sentinel lambs were comingled during the experiment. Lambs were weaned at 60 d of age, bled 1 wk after weaning, and thereafter at intervals of 4 or 5 wk until 9 mo of age when OPPV infection status was determined by use of a competitive enzyme-linked immunosorbent assay. Only 1 sentinel lamb became infected. Infection status of trial lambs was analyzed using logistic regression procedures to account for the binary nature of infection status and random effects of sires. Effects of sex, type of birth, type of rearing, age of dam, breed type of dam, and sires were not detected (P>0.20). Infection status was affected by diplotype of lamb (P=0.005), with additive (P=0.002) and dominance (P=0.052) effects identified. Predicted probabilities of infection for lambs with diplotypes "1 1," "1 3," and "3 3" were 0.094, 0.323, and 0.346, respectively. Confidence intervals for probabilities of infection for diplotypes "1 3" and "3 3" were similar, but distinct from diplotype "1 1." These results are consistent with complete dominance of haplotype 3 relative to haplotype 1. The probability of infection at 9 mo of age for lambs with either diplotype "1 3" or "3 3" averaged 3.56 times that of lambs with diplotype "1 1." Genetic susceptibility to OPPV infection can be reduced by selection to increase the frequency of haplotype 1, resulting in a greater proportion of lambs with diplotype "1 1."
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Affiliation(s)
- K A Leymaster
- USDA-ARS, Roman L. Hruska US Meat Animal Research Center, Clay Center, NE 68933-0166
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21
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Larruskain A, Jugo BM. Retroviral infections in sheep and goats: small ruminant lentiviruses and host interaction. Viruses 2013; 5:2043-61. [PMID: 23965529 PMCID: PMC3761241 DOI: 10.3390/v5082043] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 07/26/2013] [Accepted: 08/05/2013] [Indexed: 12/18/2022] Open
Abstract
Small ruminant lentiviruses (SRLV) are members of the Retrovirus family comprising the closely related Visna/Maedi Virus (VMV) and the Caprine Arthritis-Encephalitis Virus (CAEV), which infect sheep and goats. Both infect cells of the monocyte/macrophage lineage and cause lifelong infections. Infection by VMV and CAEV can lead to Visna/Maedi (VM) and Caprine Arthritis-Encephalitis (CAE) respectively, slow progressive inflammatory diseases primarily affecting the lungs, nervous system, joints and mammary glands. VM and CAE are distributed worldwide and develop over a period of months or years, always leading to the death of the host, with the consequent economic and welfare implications. Currently, the control of VM and CAE relies on the control of transmission and culling of infected animals. However, there is evidence that host genetics play an important role in determining Susceptibility/Resistance to SRLV infection and disease progression, but little work has been performed in small ruminants. More research is necessary to understand the host-SRLV interaction.
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Affiliation(s)
- Amaia Larruskain
- Genomics and Health Group, Department of Genetics, Physical Anthropology and Animal Physiology, Faculty of Science and Technology, University of the Basque Country UPV/EHU, Bilbao 48080, Spain.
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22
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Pérez M, Muñoz JA, Biescas E, Salazar E, Bolea R, de Andrés D, Amorena B, Badiola JJ, Reina R, Luján L. Successful Visna/maedi control in a highly infected ovine dairy flock using serologic segregation and management strategies. Prev Vet Med 2013; 112:423-7. [PMID: 24054307 DOI: 10.1016/j.prevetmed.2013.07.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2013] [Revised: 07/26/2013] [Accepted: 07/31/2013] [Indexed: 11/19/2022]
Abstract
A control system for Visna/maedi virus (VMV) infection based on serologic segregation and management strategies was applied in an infected Spanish dairy Manchega breed sheep flock (n=670) that was affected by a severe respiratory process associated to VMV. The control started in 2004 and consisted on the serological study of animals, segregation in two different flocks (seropositive and seronegative), separate management of flocks, selection of young female lambs for replacement only from seronegative ewes offspring, immediate removal of seropositive animals detected in the seronegative flock and a management tending toward the reduction and final culling of the seropositive flock. The serological control was repeated yearly or twice a year, approximately. Initial VMV seroprevalence of the undivided flock was 66.4% (January 2004) that descended to 47.3%, 12.8%, 2.2% and 0.2% between July 2004 and May 2006. Residual seroprevalence fluctuated slightly thereafter with a peak of 2.2% in April 2008. After segregation, number of animals in the seronegative flock was 378 that descended to 323 in October 2005. Since then, this number has increased steadily reaching 650 sheep in December 2011. The seropositive flock was progressively reduced by culling until its total disappearance in June 2010. This work presents the detailed results obtained in the control strategy against VMV in a single dairy sheep flock by implementing a segregation system based on serologic testing. The system is highly successful, as it reduces to residual levels VMV infection in about two years without the need of culling a high number of animals, as required by other methods. Moreover, the original size flock was been recovered within 8 years and has led to a subjective improvement of animal health and welfare in the flock. The residual seroprevalence could be eliminated at this stage by applying more sensitive molecular or other serological techniques to reach eradication.
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Affiliation(s)
- M Pérez
- Department of Anatomy, Embryology and Genetics, University of Zaragoza, Spain
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Polledo L, González J, Fernández C, Miguélez J, Martínez-Fernández B, Morales S, Ferreras M, Marín JG. Simple control strategy to reduce the level of Maedi-Visna infection in sheep flocks with high prevalence values (>90%). Small Rumin Res 2013. [DOI: 10.1016/j.smallrumres.2012.12.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Small ruminant lentiviruses: genetic variability, tropism and diagnosis. Viruses 2013; 5:1175-207. [PMID: 23611847 PMCID: PMC3705272 DOI: 10.3390/v5041175] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Revised: 04/09/2013] [Accepted: 04/12/2013] [Indexed: 02/05/2023] Open
Abstract
Small ruminant lentiviruses (SRLV) cause a multisystemic chronic disease affecting animal production and welfare. SRLV infections are spread across the world with the exception of Iceland. Success in controlling SRLV spread depends largely on the use of appropriate diagnostic tools, but the existence of a high genetic/antigenic variability among these viruses, the fluctuant levels of antibody against them and the low viral loads found in infected individuals hamper the diagnostic efficacy. SRLV have a marked in vivo tropism towards the monocyte/macrophage lineage and attempts have been made to identify the genome regions involved in tropism, with two main candidates, the LTR and env gene, since LTR contains primer binding sites for viral replication and the env-encoded protein (SU ENV), which mediates the binding of the virus to the host’s cell and has hypervariable regions to escape the humoral immune response. Once inside the host cell, innate immunity may interfere with SRLV replication, but the virus develops counteraction mechanisms to escape, multiply and survive, creating a quasi-species and undergoing compartmentalization events. So far, the mechanisms of organ tropism involved in the development of different disease forms (neurological, arthritic, pulmonary and mammary) are unknown, but different alternatives are proposed. This is an overview of the current state of knowledge on SRLV genetic variability and its implications in tropism as well as in the development of alternative diagnostic assays.
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de Andrés X, Ramírez H, Bertolotti L, San Román B, Glaria I, Crespo H, Jáuregui P, Minguijón E, Juste R, Leginagoikoa I, Pérez M, Luján L, Badiola JJ, Polledo L, García-Marín JF, Riezu JI, Borrás-Cuesta F, de Andrés D, Rosati S, Reina R, Amorena B. An insight into a combination of ELISA strategies to diagnose small ruminant lentivirus infections. Vet Immunol Immunopathol 2013; 152:277-88. [PMID: 23375019 DOI: 10.1016/j.vetimm.2012.12.017] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Revised: 12/20/2012] [Accepted: 12/28/2012] [Indexed: 02/08/2023]
Abstract
A single broadly reactive standard ELISA is commonly applied to control small ruminant lentivirus (SRLV) spread, but type specific ELISA strategies are gaining interest in areas with highly prevalent and heterogeneous SRLV infections. Short (15-residue) synthetic peptides (n=60) were designed in this study using deduced amino acid sequence profiles of SRLV circulating in sheep from North Central Spain and SRLV described previously. The corresponding ELISAs and two standard ELISAs were employed to analyze sera from sheep flocks either controlled or infected with different SRLV genotypes. Two outbreaks, showing SRLV-induced arthritis (genotype B2) and encephalitis (genotype A), were represented among the infected flocks. The ELISA results revealed that none of the assays detected all the infected animals in the global population analyzed, the assay performance varying according to the genetic type of the strain circulating in the area and the test antigen. Five of the six highly reactive (57-62%) single peptide ELISAs were further assessed, revealing that the ELISA based on peptide 98M (type A ENV-SU5, consensus from the neurological outbreak) detected positives in the majority of the type-A specific sera tested (Se: 86%; Sp: 98%) and not in the arthritic type B outbreak. ENV-TM ELISAs based on peptides 126M1 (Se: 82%; Sp: 95%) and 126M2 0,65 0.77 (Se: 68%; Sp: 88%) detected preferentially caprine arthritis encephalitis (CAEV, type B) and visna/maedi (VMV, type A) virus infections respectively, which may help to perform a preliminary CAEV vs. VMV-like typing of the flock. The use of particular peptide ELISAs and standard tests individually or combined may be useful in the different areas under study, to determine disease progression, diagnose/type infection and prevent its spread.
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Affiliation(s)
- X de Andrés
- Institute of Agrobiotechnology (CSIC-UPNA-Gobierno de Navarra), Navarre, Spain
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Quantitative estimation of the impact of caprine arthritis encephalitis virus infection on milk production by dairy goats. Vet J 2013; 197:311-7. [PMID: 23384438 DOI: 10.1016/j.tvjl.2012.12.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2012] [Revised: 11/16/2012] [Accepted: 12/21/2012] [Indexed: 11/21/2022]
Abstract
This retrospective study investigated milk production losses associated with serological evidence (serostatus) of caprine arthritis encephalitis virus (CAEV) infection over one lactation in 4543 Murciano-Granadina goats from 22 herds in Spain. The seroprevalence of infection was 18%, ranging from 0% to 2% in 11 herds, 7% to 60% in 10 herds and was 100% in one herd. Seropositive does had significantly shorter lactations, produced less milk and milk fat, lactose and dry extract and had higher somatic cell counts than their seronegative counterparts, although differences in milk production between seropositive and seronegative animals were noted between herds. Mixed regression models confirmed the association between CAEV seropositivity and reduced milk production. The adjusted, least squares mean (LSM) test-day milk yield was 10% less in seropositive compared to seronegative does and this difference varied according to lactation number. In contrast, differences in the LSM of milk fat, lactose and dry extract percentages between seropositive and seronegative goats were only between 0.1% and 0.2% and did not increase with lactation number. The findings of this study provide strong evidence that CAEV-infection can be a major cause of reduction in milk yield in goats and its control should be considered as part of dairy goat herd health schemes.
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First molecular characterization of visna/maedi viruses from naturally infected sheep in Turkey. Arch Virol 2012; 158:559-70. [PMID: 23124887 DOI: 10.1007/s00705-012-1518-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2012] [Accepted: 09/17/2012] [Indexed: 10/27/2022]
Abstract
Recent worldwide serological and genetic studies of small ruminant lentiviruses (SRLV) have led to the description of new genotypes and the development of new diagnostic tests. This study investigated the detection and molecular characterization of visna/maedi virus (VMV) infection in serum and blood samples from pure and mixed sheep breeds acquired from different regions in Turkey using ELISA and PCR techniques. The prevalence of VMV was 67.8 % by ELISA and/or LTR-PCR with both assays showing a medium level of agreement (kappa: 0.26; ± 0.038 CI). Positivity of VMV in sheep increased according to the age of the animal, although PCR positivity was higher than ELISA in young individuals. Phylogenetic analysis of 33 LTR sequences identified two distinct clades that were closely related to American and Greek LTR sequences. Phylogenetic analysis of 10 partial gag gene sequences identified A2, A3, A5, A9, A11 subtypes of genotype A SRLVs. In vitro culture of all isolates in fetal sheep lung cells (FSLC) showed a slow/low phenotype causing less or no lytic infection compared with infection with the WLC-1 American strain characterized by a rapid/highly lytic phenotype. Phylogenetic analysis revealed that Turkish VMV sequences preceded the establishment of American or Greek strains that were associated with the migration of sheep from the Middle East to Western Europe several centuries ago. This is the first study that describes Turkish VMV sequences with the molecular characterization of LTR and gag genes, and it strongly suggests that SRLV-genotype A originated in Turkey.
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Ramírez H, Reina R, Bertolotti L, Cenoz A, Hernández MM, San Román B, Glaria I, de Andrés X, Crespo H, Jáuregui P, Benavides J, Polledo L, Pérez V, García-Marín JF, Rosati S, Amorena B, de Andrés D. Study of compartmentalization in the visna clinical form of small ruminant lentivirus infection in sheep. BMC Vet Res 2012; 8:8. [PMID: 22281181 PMCID: PMC3328241 DOI: 10.1186/1746-6148-8-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 01/26/2012] [Indexed: 02/08/2023] Open
Abstract
Background A central nervous system (CNS) disease outbreak caused by small ruminant lentiviruses (SRLV) has triggered interest in Spain due to the rapid onset of clinical signs and relevant production losses. In a previous study on this outbreak, the role of LTR in tropism was unclear and env encoded sequences, likely involved in tropism, were not investigated. This study aimed to analyze heterogeneity of SRLV Env regions - TM amino terminal and SU V4, C4 and V5 segments - in order to assess virus compartmentalization in CNS. Results Eight Visna (neurologically) affected sheep of the outbreak were used. Of the 350 clones obtained after PCR amplification, 142 corresponded to CNS samples (spinal cord and choroid plexus) and the remaining to mammary gland, blood cells, bronchoalveolar lavage cells and/or lung. The diversity of the env sequences from CNS was 11.1-16.1% between animals and 0.35-11.6% within each animal, except in one animal presenting two sequence types (30% diversity) in the CNS (one grouping with those of the outbreak), indicative of CNS virus sequence heterogeneity. Outbreak sequences were of genotype A, clustering per animal and compartmentalizing in the animal tissues. No CNS specific signature patterns were found. Conclusions Bayesian approach inferences suggested that proviruses from broncoalveolar lavage cells and peripheral blood mononuclear cells represented the common ancestors (infecting viruses) in the animal and that neuroinvasion in the outbreak involved microevolution after initial infection with an A-type strain. This study demonstrates virus compartmentalization in the CNS and other body tissues in sheep presenting the neurological form of SRLV infection.
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Affiliation(s)
- Hugo Ramírez
- Instituto de Agrobiotecnología, CSIC-UPNA-Gobierno de Navarra, 31192 Mutilva, Navarra, Spain
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Reduced lentivirus susceptibility in sheep with TMEM154 mutations. PLoS Genet 2012; 8:e1002467. [PMID: 22291605 PMCID: PMC3266874 DOI: 10.1371/journal.pgen.1002467] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 11/21/2011] [Indexed: 11/19/2022] Open
Abstract
Visna/Maedi, or ovine progressive pneumonia (OPP) as it is known in the United States, is an incurable slow-acting disease of sheep caused by persistent lentivirus infection. This disease affects multiple tissues, including those of the respiratory and central nervous systems. Our aim was to identify ovine genetic risk factors for lentivirus infection. Sixty-nine matched pairs of infected cases and uninfected controls were identified among 736 naturally exposed sheep older than five years of age. These pairs were used in a genome-wide association study with 50,614 markers. A single SNP was identified in the ovine transmembrane protein (TMEM154) that exceeded genome-wide significance (unadjusted p-value 3×10−9). Sanger sequencing of the ovine TMEM154 coding region identified six missense and two frameshift deletion mutations in the predicted signal peptide and extracellular domain. Two TMEM154 haplotypes encoding glutamate (E) at position 35 were associated with infection while a third haplotype with lysine (K) at position 35 was not. Haplotypes encoding full-length E35 isoforms were analyzed together as genetic risk factors in a multi-breed, matched case-control design, with 61 pairs of 4-year-old ewes. The odds of infection for ewes with one copy of a full-length TMEM154 E35 allele were 28 times greater than the odds for those without (p-value<0.0001, 95% CI 5–1,100). In a combined analysis of nine cohorts with 2,705 sheep from Nebraska, Idaho, and Iowa, the relative risk of infection was 2.85 times greater for sheep with a full-length TMEM154 E35 allele (p-value<0.0001, 95% CI 2.36–3.43). Although rare, some sheep were homozygous for TMEM154 deletion mutations and remained uninfected despite a lifetime of significant exposure. Together, these findings indicate that TMEM154 may play a central role in ovine lentivirus infection and removing sheep with the most susceptible genotypes may help eradicate OPP and protect flocks from reinfection. Ovine lentivirus targets the host immune system and causes persistent retroviral infections affecting millions of sheep worldwide. In primates, lentivirus resistance is attributed to mutant virus coreceptors that are not expressed. In sheep, some animals are resistant to lentivirus infection despite repeated exposure; however, the mechanism of resistance is unknown. We designed a genome-wide association study to test whether sheep might have genetic variation that protects against lentivirus infection. Our results showed that variation in an ovine gene (TMEM154) was associated with infection. Sheep with the ancestral type of this gene were nearly three times more likely to become infected than those with mutant forms. We also discovered two mutant forms predicted to abolish the protein's function. Although the biological function of TMEM154 is unknown, our results indicate that it plays an important role in lentivirus infection in sheep. Producing sheep with the least susceptible form of TMEM154 may help eradicate the ovine disease caused by lentivirus.
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Lago N, López C, Panadero R, Cienfuegos S, Pato J, Prieto A, Díaz P, Mourazos N, Fernández G. Seroprevalence and risk factors associated with Visna/Maedi virus in semi-intensive lamb-producing flocks in northwestern Spain. Prev Vet Med 2011; 103:163-9. [PMID: 21993274 DOI: 10.1016/j.prevetmed.2011.09.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 09/16/2011] [Accepted: 09/17/2011] [Indexed: 11/26/2022]
Abstract
A cross-sectional study was carried out to determine Visna/Maedi virus (VMV) seroprevalence and risk factors in semi-intensive lamb-producing flocks as a prelude to establishing a monitoring program in northwestern (NW) Spain. A total of 15,155 serum samples were taken from 78 commercial flocks and were submitted to an indirect VMV ELISA. Association between potential risk factors and seroprevalence at the flock level was assessed using a multivariable logistic regression model. A Generalized Estimating Equations (GEE) model and Exhaustive Chi-squared Automatic Interaction Detector (CHAID) were used to determine the seropositivity against VMV at the individual animal level. Individual seropositivity was 24.8% while 52.6% of the flocks examined had a true seroprevalence ≥1%. Flock size and introduction of new animals in the flock were significantly associated with seropositivity at the flock level. Flock size, sheep-goat contact, type of housing of lambs prior to weaning and age were significantly associated with individual VMV seropositivity. Confinement of lambs in preweaning lamb groups and high sheep-goat contact, regardless of the low number of goats per flock, were risk factors associated with individual VMV seropositivity, suggesting that these two factors are crucial for VMV control in semi-intensive lamb-producing flocks. These factors should be considered for developing more efficient strategies that will reduce the rate of VMV transmission.
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Affiliation(s)
- N Lago
- Department of Animal Health, University of Santiago de Compostela, Lugo, Spain.
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Brinkhof J, Houwers D, Moll L, Dercksen D, van Maanen C. Diagnostic performance of ELISA and PCR in identifying SRLV-infected sheep and goats using serum, plasma and milk samples and in early detection of infection in dairy flocks through bulk milk testing. Vet Microbiol 2010; 142:193-8. [DOI: 10.1016/j.vetmic.2009.09.060] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2009] [Revised: 09/16/2009] [Accepted: 09/17/2009] [Indexed: 10/20/2022]
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Leginagoikoa I, Minguijón E, Juste RA, Barandika J, Amorena B, de Andrés D, Badiola JJ, Luján L, Berriatua E. Effects of housing on the incidence of visna/maedi virus infection in sheep flocks. Res Vet Sci 2009; 88:415-21. [PMID: 19963230 DOI: 10.1016/j.rvsc.2009.11.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2009] [Revised: 10/14/2009] [Accepted: 11/06/2009] [Indexed: 10/20/2022]
Abstract
The incidence of seroconversion to visna/maedi virus (VMV) infection and its relationship with management and sheep building structure was investigated in 15 dairy sheep flocks in Spain during 3-7years. Incidence rates were 0.09 per sheep-year at risk in semi-intensive Latxa flocks and 0.44 per sheep-year at risk in intensive Assaf flocks and was greatest for the one year old Assaf replacement flock. Separate multivariable models developed for replacement and adult flocks indicated that in both cases seroconversion was strongly associated to direct contact exposure to infected sheep and to being born to a seropositive dam. The latter effect was independent of the mode of rearing preweaning and the risk of seroconversion was similar for sheep fed colostrum and milk from a seropositive or a seronegative dam. These results are further evidence of the efficiency of horizontal VMV transmission by close contact between sheep and also suggest a inheritable component of susceptibility and resistance to infection. In contrast, indirect aerogenous contact with seropositive sheep was not associated with seroconversion as evidenced in replacement sheep housed in separate pens in the same building as adult infected sheep for one year. Consequently, VMV may not be efficiently airborne over short distances and this is important for control of infection. Moreover, there was no relationship between seroconversion and shed open areas. The latter could be related to having examined few flocks in which high infection prevalence dominated the transmission process while ventilation, may depend on a variety of unrecorded factors whose relationship to infection needs to be further investigated.
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Affiliation(s)
- I Leginagoikoa
- Department of Animal Health, NEIKER-Instituto Vasco de Investigación y Desarrollo Agrario, Berreaga 1, 48460 Derio, Bizkaia, Spain
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Prevention strategies against small ruminant lentiviruses: An update. Vet J 2009; 182:31-7. [DOI: 10.1016/j.tvjl.2008.05.008] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 05/02/2008] [Accepted: 05/09/2008] [Indexed: 11/17/2022]
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Pérez M, Biescas E, de Andrés X, Leginagoikoa I, Salazar E, Berriatua E, Reina R, Bolea R, de Andrés D, Juste RA, Cancer J, Gracia J, Amorena B, Badiola JJ, Luján L. Visna/maedi virus serology in sheep: survey, risk factors and implementation of a successful control programme in Aragón (Spain). Vet J 2009; 186:221-5. [PMID: 19747864 DOI: 10.1016/j.tvjl.2009.07.031] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 07/29/2009] [Accepted: 07/29/2009] [Indexed: 10/20/2022]
Abstract
A serological survey of Visna/maedi virus (VMV) infection involving 274,048 sheep from 554 flocks was undertaken during 2002-2007 in Aragón, North-East Spain. One hundred and two of these flocks enrolled in a VMV control programme to reduce seroprevalence by selecting replacement lambs from seronegative dams and gradual culling of seropositive sheep. Twenty-five flocks were also visited to collect flock management and housing data. All study flocks had seropositive animals and 52.8% of animals tested were seropositive. Among flocks that joined the control programme 66 adopted the proposed measures and reduced seroprevalence significantly by between 26.1% and 76.9% whereas the remaining 36 flocks did not apply the measures and seroprevalence significantly increased. Seroprevalence increased with flock size and the number of days the sheep were housed, and decreased with increasing weaning age and shed open area, suggesting a reduced risk of VMV infection in sheep associated with better ventilation. At the end of the period, 24 flocks were certified as VMV-controlled with a seroprevalence <5%, and seven as VMV-free with 0% seroprevalence. These are the first officially recognised VMV-free flocks in Spain and represent a nucleus of VMV-free replacement animals for other flocks. Moreover, they are evidence of the possibility of eliminating VMV infection without resorting to whole-flock segregation or culling of seropositive sheep.
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Affiliation(s)
- M Pérez
- Department of Animal Pathology, Veterinary Faculty, University of Zaragoza, 177 Miguel Servet Street, 50013 Zaragoza, Spain
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Leginagoikoa I, Minguijón E, Berriatua E, Juste R. Improvements in the detection of small ruminant lentivirus infection in the blood of sheep by PCR. J Virol Methods 2009; 156:145-9. [DOI: 10.1016/j.jviromet.2008.11.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 11/18/2008] [Accepted: 11/24/2008] [Indexed: 10/21/2022]
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Peterson K, Brinkhof J, Houwers D, Colenbrander B, Gadella B. Presence of pro-lentiviral DNA in male sexual organs and ejaculates of small ruminants. Theriogenology 2008; 69:433-42. [DOI: 10.1016/j.theriogenology.2007.10.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Revised: 10/15/2007] [Accepted: 10/18/2007] [Indexed: 11/28/2022]
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Brinkhof J, van Maanen C, Wigger R, Peterson K, Houwers D. Specific detection of small ruminant lentiviral nucleic acid sequences located in the proviral long terminal repeat and leader-gag regions using real-time polymerase chain reaction. J Virol Methods 2008; 147:338-44. [DOI: 10.1016/j.jviromet.2007.10.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Revised: 10/02/2007] [Accepted: 10/10/2007] [Indexed: 10/22/2022]
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Leginagoikoa I, Juste RA, Barandika J, Amorena B, De Andrés D, Luján L, Badiola J, Berriatua E. Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep. Vet Res 2006; 37:767-78. [PMID: 16973117 DOI: 10.1051/vetres:2006034] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Accepted: 05/03/2006] [Indexed: 11/15/2022] Open
Abstract
Maedi-Visna Virus (MVV) seroprevalence and its relationship with housing and mode of rearing of replacement ewe-lambs was investigated in 38 non-randomly selected sheep-flocks in Spain. They included extensive lamb-producing Manchega cross-bred flocks raised almost permanently at pasture, semi-intensive Latxa dairy flocks housed 2-8 months/year and intensively raised Assaf dairy flocks housed most time and at higher stocking density in less ventilated buildings than other flocks. Most flocks raised replacement lambs naturally with their dams until weaning and as a separate flock thereafter until lambing at one year of age. Seroprevalence (95% confidence intervals) was 77%, 25% and 5% (4-6) in intensive, semi-intensive and extensive flocks, respectively and the median (interquartile range) flock-seroprevalence was 82% (66-94) in intensive flocks, 31% (14-31) in semi-intensive flocks and 4% (0-7) in extensive flocks. Seroprevalence was lowest in one year-old sheep and increased to flock levels during the year after introduction into the adult flock in most intensive flocks and more gradually in other flocks. Adult flock seroprevalence was associated with housing time but this relationship was not evident within a particular rearing system, indicating that other unknown factors are critical in horizontal MVV-transmission. Low seroprevalence in extensive flocks further supports previous indications that lactogenic MVV-infection is relatively inefficient and horizontal transmission is necessary to ensure long-term maintenance of MVV and this could explain that MVV has not been reported from countries with mainly extensively reared sheep such as Australia and New Zealand. Moreover, it indicates that MVV-control in extensive and semi-intensive flocks can be simple and inexpensive.
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Affiliation(s)
- Iratxe Leginagoikoa
- Instituto Vasco de Investigación y Desarrollo Agrario-NEIKER, Derio, Bizkaia, Spain
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