Risk Factors for Transmission and Methods for Control of Caprine Arthritis-Encephalitis Virus Infection

Rowe, Joan D; East, Nancy

doi:10.1016/s0749-0720(15)30363-7

Cited by 120 publications

(106 citation statements)

References 43 publications

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“…As indicated before, the veterinarian responsible for the intensively raised flocks had expressed concern for MVV-infection and the contrary was the case for the veterinarian looking after the extensive flocks and this could be a source of strong selection bias. However, similarly high SRLV-seroprevalence is typical for example in intensive dairy goat herds in California [28] and in Icelandic sheep kept in close confinement in the winter [20] and similar low and null SRLV-seroprevalence was reported in extensive flocks in Patagonia [25,26]. Further bias might have been introduced by selecting the smaller flocks in the extensive system and those registered with the local milk-board among intensive flocks, but it is unlikely that either factor contributes greatly to explaining the enormous differences in MVV-seroprevalence in these two sheep production systems.…”

Section: Discussionmentioning

confidence: 99%

Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

et al. 2006

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-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.Maedi-Visna Virus / sheep / seroprevalence / intensive and extensive rearing / Spain

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Section: Discussionmentioning

confidence: 99%

Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

et al. 2006

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“…The fact that some SRLV subtypes have been isolated from both sheep and goats furthermore indicates that interspecies transmission must have occurred at least once in each of these subtypes, although the frequency and direction of transmission remain unknown (12,21,22,32). While interspecies transmission from goats to sheep under natural conditions has never been observed (1,16,23,27), we have recently forwarded statistical evidence suggesting that transmission of the newly discovered SRLV subtype A4 from sheep to goats must occur regularly, though rarely (26).…”

mentioning

confidence: 96%

Direct Evidence for Natural Transmission of Small-Ruminant Lentiviruses of Subtype A4 from Goats to Sheep and Vice Versa

Shah

Huder

Böni

et al. 2004

J Virol

113

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Small-ruminant lentiviruses (SRLV), which include the caprine arthritis-encephalitis and the maedi-visna virus, cause persistent inflammatory infections in goats and sheep. SRLV are mainly transmitted from mother to offspring through milk. Transmission after prolonged contact between adult animals has also been observed. The observation that certain SRLV subtypes are found in both goats and sheep suggests that interspecies transmission has occurred on several occasions in the past. We investigated seropositive goats and sheep that were kept together in small mixed herds. Phylogenetic analysis of long proviral sequences in gag and pol, combined with epidemiologic information, demonstrated natural sheep-to-goat transmission of the recently identified SRLV subtype A4 in two instances and goat-to-sheep transmission of the same subtype in one instance. In a further mixed cluster, the direction of the interspecies transmission could not be determined. These findings present for the first time direct evidence that natural interspecies transmission of SRLV is ongoing in both directions. The findings are of relevance to virus eradication programs in both species. (14,17,18,28). Earlier phylogenetic analysis, mostly based on short sequences, has suggested that these very diverse viruses can be divided into six different sequence clades, I to VI (12,21,22,32). Recent work based on long sequences in gag and pol of more than 100 new isolates from Switzerland and all available database sequences has, however, demonstrated that the SRLV should rather be divided into four principal sequence groups A to D, which differ by 25 to 37% in gag and pol sequences. Sequence groups A and B are further divided into different subtypes that differ from each other by 15 to 27%. Group A contains at least 7 subtypes, A1 to A7, and group B contains two subtypes, B1 and B2 (26). To date, subtypes A1 and A2 have been isolated only from sheep, and subtypes A5, A7, and B1 and groups C and D have been isolated only from goats. In contrast, subtypes A3, A4, A6, and B2 have been isolated from both sheep and goats. Caprine arthritis-encephalitis virus (CAEV) and maedivisna virus (MVV) are small-ruminant lentiviruses (SRLV) that infect goats and sheep

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“…However, they may be related to the analytical sensitivity of the diagnostic test used (KLEIN et al, 1985;EAST, 1997;ANDRÉS et al, 2005), host genetic factors, differences between sheep and goats in the stimulus of the humoral response to either some antigens or the same viral strain (FLURI et al, 2006;RACHID et al, 2013), and SRLV genotype, which influences the rates of viral replication, in which the animals infected with more virulent samples have earlier and higher titers (KAJIKAWA; LAIRMORE; DEMARTINI, 1990;RIMSTAD et al, 1993).…”

Section: Seroconversionmentioning

confidence: 99%

“…This antibody titer is reduced after 2-3 months of age. For this reason, serological test should only be recommended after this period (ROWE et al, 1992a). However, virus transmission also by the colostrum, whereby passive antibodies are transmitted to goats, is a relevant possibility to consider (GOUVEIA, 2012).…”

Section: Agarose Gel Immunodiffusion (Agid)mentioning

confidence: 99%

Use of serological diagnostic techniques in the control and eradication of caprine arthritis encephalitis: an update

Mussi

Gouveia

Cortéz

et al. 2015

Braz. J. Vet. Res. Anim. Sci.

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Caprine arthritis encephalitis (CAE) is a chronic disease caused by a small ruminant lentivirus (SRLV), which causes significant losses in goat breeding. The actual state of animal infection with SRLV is difficult to determine due to a complex pathogenesis of the virus, including factors such as delayed or intermittent seroconversion in serological tests. Several serological techniques are available for disease diagnosis, such as screening or confirmation tests, which are different in sensitivity and specificity. Regarding the choice of the test to be applied, availability of commercial immunoreagents, team training, antigen used, and cost of techniques must be considered. This review presents the serological methods available for use in different stages of CAE control and eradication programs, and management measures to be adopted in conjunction with serological diagnosis of the disease.Keywords: Caprine arthritis encephalitis virus. CAEV. Small ruminant lentivirus. SRLV. Diagnosis. Control. ResumoA artrite encefalite caprina (CAE) é uma enfermidade crônica causada por um lentivírus de pequenos ruminantes (LVPR), que ocasiona perdas significativas na caprinocultura. O estado real da infecção animal pelo LVPR é de difícil determinação em virtude da complexa patogenia do vírus, incluindo fatores como soroconversão tardia ou intermitente em testes sorológicos. Para o diagnóstico da enfermidade, diversas técnicas sorológicas estão disponíveis, como testes de triagem ou confirmatórios, com variações na sensibilidade e especificidade. Para escolha do teste a ser usado, a disponibilidade de imunorreagentes comerciais, o treinamento da equipe, o antígeno utilizado, e o custo das técnicas devem ser considerados. Esta revisão apresenta os métodos sorológicos disponíveis para uso em diferentes fases dos programas de controle e erradicação da CAE e as medidas de manejo que devem ser adotadas em conjunto com o diagnóstico sorológico da enfermidade. Palavras

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Risk Factors for Transmission and Methods for Control of Caprine Arthritis-Encephalitis Virus Infection

Cited by 120 publications

References 43 publications

Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

Direct Evidence for Natural Transmission of Small-Ruminant Lentiviruses of Subtype A4 from Goats to Sheep and Vice Versa

Use of serological diagnostic techniques in the control and eradication of caprine arthritis encephalitis: an update

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