Caprine Arthritis Encephalitis Research Articles

Metagenomic analysis of goat feces from Ogliastra (Sardinia, Italy)

With its constitutive and functional characteristics, the intestinal microbiota plays a crucial role in the health condition of the animals. Variations in the composition and gene expression of the intestinal microbiota are associated with the risk of the onset of various pathologies of the gastrointestinal tract and chronic inflammatory intestinal diseases. The objectives of this study were to evaluate the variability in the composition of the intestinal microbiota of goats of different breeds (Sarda, Maltese, and Alpine) farmed in different flocks of the region of Ogliastra (Sardegna, Italy) and to assess whether the type of feeding (natural pasture grazing-based versus intensive) could affect the intestinal bacterial composition. We also evaluated possible differences in the composition of the intestinal microbiota between healthy and Caprine arthritis encephalitis (CAE)-affected goats. The economic damage caused by this pathology is due to the reduction in milk production, with infected animals having greater susceptibility to contract diseases. The results of our study highlighted a statistically significant difference (P = 0.001–0.005) in the intestinal bacterial composition between the intensively managed flock and the other natural pasture-based flock.g In particular, a significantly greater abundance of Acidoaminococcaceae in the intensive flock was obgserved. Furthermore, a significantly greater abundance of Prevotellaceae was found in two localities in which, out of a total of 29 animals, only four tested negative for CAE. From these data, we deduced that the presence of Prevotellaceae can be an indication of the disease. This difference could be attributed to the farming system, the Cardedu farm being the only intensive one, and to the geographical distance of this location from the other sampling sites. Therefore, the results of the present study suggest that extensive or intensive farm management may affect the intestinal microbiota of goats.

Study of possible intrauterine infection of goat fetus with caprine arthritis-encephalitis virus

Caprine arthritis-encephalitis is a serious challenge for the modern goat breeding both in Russia and abroad. The disease is quite widespread in our country, causing serious economic damage to the backyard and family-operated farm owners. The etiologic agent of caprine arthritis-encephalitis (CAE) is a virus of the Retroviridae family, which is part of the group of small ruminant lentiviruses subdivided into five genetic groups. A number of reasons prevent timely disease diagnosis, for example, lack of a legal framework regulating preventive measures, prolonged asymptomatic virus-carrier state, and absence of pathognomonic symptoms. There are two routes of the CAE virus spread: vertical (lactogenic), when colostrum or milk from a seropositive goat serves as a transmission factor; and horizontal – from a diseased animal to a healthy one in case of crowded housing, feeding from common drinkers and feeders, as well as during mating. The published data on the possibility of the intrauterine virus transmission from mother to fetus are diametrically different. The purpose of this study was to explore the possibility of intrauterine infection with the CAE virus. Pregnant goats with ELISAand PCR-confirmed CAE diagnosis were used in the study. Pathological material was collected from newborn goats obtained by sterile kidding, and the samples were PCR tested for the CAE causative agent. None of the tested samples demonstrated CAE that gives evidence of absence of the fact of intrauterine virus transmission from the diseased mother to the fetus. Results of long-term monitoring of the goat population kept on two backyards located in the Southern Federal District and Novosibirsk Oblast comprise an indirect evidence of that. The owners of these backyards, where 100% of the goat population were infected with CAE virus, decided to carry out a complex of the disease control measures. Sterile kidding followed by kids’feeding with colostrum and milk pasteurized at 60 °C for 30 minutes with the subsequent use of a whole milk substitute allowed to obtain a CAE-free herd in two years avoiding any significant economic losses and purchase of healthy animals from other farms.

The herd-level prevalence of caprine arthritis-encephalitis and genetic characteristics of small ruminant lentivirus in the Lithuanian goat population

Caprine arthritis-encephalitis (CAE) is a progressive disease of goats caused by small ruminant lentivirus (SRLV) and is considered as one of the most important threats for goat farming in developed countries. The disease prevalence has never been investigated in the Lithuanian goat population. Therefore, a descriptive cross-sectional study was carried out in 2021–2022 to determine if SRLV infection was present in the Lithuanian goat population and, in the case of a positive result, to estimate the true herd-level prevalence of SRLV infection and specify genotypes and subtypes of SRLV responsible for the infection. Thirty goat herds counting >5 adult goats were randomly selected and, in each herd, a representative sample of adult goats was blood-sampled and tested serologically for SRLV infection using a commercial ELISA. The herd was considered infected if at least one goat tested positive and the true herd-level prevalence of SRLV infection was estimated using the Bayesian approach. Seropositive animals were found in 17 / 30 herds (57 %; 95 % confidence interval: 39 %, 73 %). The true herd-level prevalence was 56 % (95 % credible interval: 36 %, 76 %). In 10 / 17 seropositive herds whose owners consented for resampling of seropositive goats, 1–5 seropositive goats were tested using the nested real-time PCR (nRT-PCR). Goats from 9 seropositive herds tested positive in the nRT-PCR: in 4 herds for genotype A, in 4 herds for genotype B, and in 1 herd – 2 goats for genotype B and 1 goat for genotype A. From each of 9 nRT-PCR-positive herds, 1 PCR product of each genotype was sequenced using Sanger method and the phylogenic tree was constructed using the neighbor-joining method in the Molecular Evolutionary Genetics Analysis software. Four herds turned out to be infected with B1 subtype (91 % identity with the prototypic strain), 3 herds with A2 subtype (90 %-92 % identity), and a herd with mixed infection was infected with B1 (91 % identity) and A2 subtype (90 % identity). In one herd, the only seropositive goat was found to be infected with the strain most closely related to the A1 subtype (80 % identity). This study shows for the first time that SRLV infection is present and widespread in the Lithuanian goat population and both classical SRLV genotypes, represented by quite typical subtypes A2 and B1, appear to be responsible for the infection.

Investigation of seroprevalence of small ruminant lentivirus infections in Erzurum province of Türkiye and determination of individual and environmental variables

Small ruminant lentiviruses (SRLVs) are chronic, incurable, and vaccine-free viral diseases that cause respiratory problems and nervous disorders and yield losses in sheep and goats. Caprine arthritis encephalitis virus in goats and maedi-visna virus in sheep have been named as SRLVs. This study aimed to determine the epidemiological status of SRLV infection in Erzurum province and to evaluate the risk factors of the disease based on breed, age, and sex. For this purpose, 204 animals including 184 sheep (Akkaraman, Morkaraman, and Hemşin breeds) and 20 goats (Anatolian Black goats) from 8 districts of Erzurum province (Aşkale, Hınıs, Horasan, Karaçoban, Palandöken, Pasinler, Pazaryolu, and Tekman) were included in the sample. Commercial antibody-ELISA kit was used to determine the seroprevalence of SRLV and 15.12% seropositivity was detected. In terms of SRLV, 14.67% of females and 20% of males were positive. In terms of breed, 20%, 13.76%, 0%, and 15% seropositivity was determined in Akkaraman, Morkaraman and Hemşin breed sheep and Anatolian Black goats, respectively. Although there was no statistically significant difference in terms of breed groups and sex, the detection rates in the districts were significant. In conclusion, the prevalence of SRLV infection was investigated in 8 locations of Erzurum province, which is one of the important centers of animal breeding and where small ruminant breeding is at a high level, and significant findings were obtained at the district level. With this study, updated data on seroprevalence of SRLV in the region were obtained and a broader perspective was tried to be provided by comparing with other SRLV studies in Türkiye and the world. These findings are important in terms of evaluating the prevalence and transmission risks of SRLV infections in the region and will shed light on future control and prevention strategies.

Dairy goat doe-kid rearing systems: Farmers' motivations and a description of practices, benefits, and drawbacks

In French dairy goat systems, kids are generally separated from their mother does shortly after birth. The main drivers of this practice are related to health-especially the prevention of the Caprine Arthritis Encephalitis Virus (CAEV) transmission-and economics. However, the separation of young ruminants from their does is being increasingly questioned by society and has raised concerns about the satisfaction of their behavioral needs. Some farmers choose to leave their female kids with their does. The aims of this study were to understand their motivations for leaving kids with their does, to describe how kids are reared in this case and how farmers perceive different aspects of the impacts of this practice. Individual semi-structured interviews were carried out with 40 farmers who had implemented the kids-with-does practice for at least one year. Compared with the national database describing the French population of dairy goat farmers, the characteristics of the interviewed farmers differed from those of the general population. They were younger and had done longer studies. Their farms were smaller, mainly with rare breeds and milk was mainly processed on-farm under an organic certification system. They chose to implement this practice for different reasons: ethical considerations, improving integration of kids within the herd, saving time and increasing comfort at work or improving the kids' growth, welfare, and health. The doe-kid rearing contact practices varied greatly between farms, with some kids staying with their does from a period of 45 d to never being separated; furthermore, some kids remained with their does all day, while others remained together part of the day or for a limited time, and daily contact evolved over time. Overall, farmers were satisfied as the benefits quoted were coherent with their motivations to implement this rearing practice. Most have decided to continue the practice, though usually with changes. However, as 40% of them had only 3 years or less of experience of doe-kid rearing, some had not sufficient hindsight into long-term issues such as the transmission of CAEV. It is crucial to tackle challenges associated with this practice, i.e., potentially wild kids, health issues, and economic consequences stemming from a reduction in marketable milk.

Detection and Phylogenetic Analysis of Caprine Arthritis Encephalitis Virus Using TaqMan-based qPCR in Eastern China.

Caprine arthritis encephalitis is an infectious disease caused by the caprine arthritis encephalitis virus that infects goats, sheep, and other small ruminants. An outbreak of CAEV could be extremely harmful to the goat farming industry and could cause severe economic losses. We designed specific primers and probes for the gag gene and established a TaqMan real-time quantitative polymerase chain reaction assay. This method's correlation coefficient (R2) was >0.999, and the sensitivity of the assay to the plasmid-carried partial gag gene was approximately 10 copies/µL, 1000 times higher than that of conventional PCR. No specific fluorescence was detected for other sheep viruses. Using this method, we tested 776 asymptomatic sheep blood samples and 4 neurodegenerative sheep brain samples from six farms in eastern China, and the positivity rate was 0.77% (6/780). The gag gene was partially sequenced in the three positive samples and compared with the sequences from other representative strains in GenBank. The results revealed that all three strains belonged to the B1 subtype and were most closely related to the strains from Shanxi and Gansu, previously isolated in China, with their homology ranging from 97.7% to 98.9%. These results suggest that the designed RT-qPCR assay can be used to detect subclinical CAEV in sheep and that the virus is still present in eastern China.

High positivity rate of caprine arthritis encephalitis virus in Luzon, the Philippines revealed by nested-polymerase chain reaction assay.

Caprine arthritis encephalitis (CAE) is a worldwide economically important disease of small ruminants particularly goats. CAE has been considered to be an emerging/re-emerging disease of goats and a notifiable disease in the Philippines. In this study, a nested-PCR method to detect CAE virus (CAEv) infection was conducted between January 2021 to December 2022. A total of 1334 goat blood samples were collected from 24 goat farms throughout Luzon, the Philippines. The over-all prevalence rate was 31.41% (419/1334) in goats and 91.67% (22/24) of goat farms. These results showed high positivity rate of CAEv and the disease may be widespread in Luzon, the Philippines.

Coxiella burnetii seroprevalence in domestic goat does in the United States: Prevalence, distribution, and associated risk factors

Infection with the bacterium Coxiella burnetii can cause coxiellosis in animals and Q fever in humans. Coxiellosis a consistently underreported infectious disease. The infection can result in reproductive consequences for humans and animals. Ruminants are a reservoir for infection and humans are generally infected via aerosolized secretions, making it a public health concern. Studies of ruminant seroprevalence are generally limited in size and scope. This study determined seroprevalence in a large-scale U.S. population of female goats using serum samples from 7736 does from 24 states.This study identified C. burnetii seroprevalence in the United States domestic goat population. Overall, 14.5 % (SE = 2.3) of does were seropositive and 21.0 % (SE = 2.4) of operations had at least 1 seropositive doe.Further, operation demographics and herd management practices associated with seropositivity were as follows: the suspected or confirmed presence of caprine arthritis encephalitis (CAE), caseous lymphadenitis (CL), Johne’s disease, or sore mouth in the herd in the previous 3 years, not cleaning or disinfecting the kidding areas or removing aborting does from other does, allowing visitors to access the kidding areas, and a lower percentage of adult goat inventory that were adult bucks or wethers. Furthermore, goat breed was associated with seropositivity.These data show C. burnetii seroprevalence in the United States and identify operation and animal characteristics and management practices associated with C. burnetii seropositivity. Together, this information can be used to help limit animal transmission, inform public health measures, and help educate and protect individuals working with goats.

Method of goat immunodiagnosis in arthritis-encephalitis

Currently, serological tests are used in the diagnosis of Caprine Arthritis Encephalitis (CAE), but a more accurate diagnosis of the disease requires the most reliable modern methods of immunodiagnosis. This is important for timely diagnosis and prevention of this disease, especially in commercial production of goat milk. At the present stage, the practice of infectious diseases immunodiagnosis in animals includes the determination of cytokines 6 and 10. The discovered cytokines allow for a different view on the infectious disease pathogenesis, while the previously used diagnostic methods are not excluded from the veterinary practice. At present, during the restoration and renewal of the goat population, new breeds purchased in foreign countries have appeared, and with them have come new diseases not previously prevalent in the Russian Federation. Therefore, practicing veterinarians need to develop the most effective immunodiagnostic tests for these diseases and work out effective control and prevention methods, as well as to be able to assess the risks of new infections or mixt infections. Immunophenotyping is performed in various infectious animal diseases, and immunological monitoring is also possible.

Caprine arthritis-encephalitis in the Sverdlovsk region and the diagnostics importance

Goat breeding products (especially dairy products) are of great importance in human dietetic nutrition. In this connection the studies into infectious diseases and maintaining of well-being in terms of especially dangerous and social infections of animals on the territory of Russia are essential. Epizootological monitoring of caprine arthritis-encephalitis in the Russian Federation has shown that the central regions, including the Urals region, are unfavourable for this disease. Diagnostic tests for caprine arthritis-encephalitis (CAE) are understudied, and there are insufficient data on treatment and prevention, for this reason, the topic of CAE studies is highly relevant and of key importance for clarifying the identification of the causative agent and blood changes in biochemical and haematological tests, when clinical signs of infection are present.

Identification and characterization of linear epitopes of monoclonal antibodies against the capsid proteins of small ruminant lentiviruses.

Maedi-visna virus (MVV) and caprine arthritis encephalitis virus (CAEV) are members of a group of genetically highly homologous lentiviruses collectively referred to as small ruminant lentiviruses (SRLVs). SRLVs can infect sheep, goats and other small ruminants, causing multisystemic disease with progressive and persistent inflammatory changes, severely reducing animal productivity and impeding animal trade. The capsid protein of SRLVs, p28, is highly conserved among strains and is a commonly used marker for the detection of SRLVs. In this study, two monoclonal antibodies (mAbs), designated G8F7 and A10C12, against p28 were generated using a recombinant p28 protein expressed in Escherichia coli as an immunogen. Functional analysis showed that these two monoclonal antibodies could be used in iELISA, immunofluorescence assays (IFA) and western blot assays to detect p28 or Gag precursor proteins of SRLVs. Two linear epitopes, 61GNRAQKELIQGKLNEEA77 (E61-77) and 187CQKQMDRVLGTRVQQATVEEKMQACR212 (E187-212), which are recognized by G8F7 and A10C12, respectively, were identified through truncation of the GST-fused p28. Amino acid sequence alignment showed that the epitope E61-77 is conserved among SRLVs, with a dominant mutation site (K72R) that does not disrupt recognition by G8F7. E187-212 was found to exhibit variability among SRLVs, but the majority of mutant epitopes are recognized by A10C12, with the exception of a mutant epitope from an isolate with undefined subtypes from Ovis aries, which was not recognized. These findings may facilitate future study of SRLVs and promote the development of methods for the detection of these viruses.

Serological evidence of Maedi-Visna and Caprine Arthritis Encephalitis in sheep and goats in the Korça region in Albania

Lentiviruses infect small ruminants and cause similar but different two significant diseases: Maedi-Visna in sheep and Caprine Arthritis Encephalitis in goats. In the current study, 91 of 413 adult sheep and goats from the Korça region tested positive for small ruminant lentiviruses. Furthermore, 11 of the 25 small ruminant herds have at least one positive animal for small ruminant lentiviruses. The overall observed herd prevalence was 44.0% (95% CI: 29–59) for both diseases, 38.6% (95% CI: 18.6-55.1) for Maedi-Visna in sheep, and 66.7% (95% CI: 43.1-90.2) for Caprine Arthritis Encephalitis in goats. The average observed prevalence rate ranges from 20% to 82.9% (95% CI: 12–89.2) within positive goat’s herds, while within sheep-positive herds, it varies from 23.1% to 57.1% (95% CI: 11.7–70.4). There was a positive correlation between seroprevalence rate and animal species; goats seem to have an odd 2.36 (OR 95% CI: 1.48-3.76) higher than sheep to test positive in ELISA. Other risk factors, such as farm size, indoor versus outdoor rearing, and close farm biosecurity, may play a role in disease transmission between and within small ruminant animals’ herds. This is the first study on the prevalence of Maedi-Visna infection in sheep and one of the few published Caprine Arthritis Encephalitis studies in Albania. These findings support the presence of Small Ruminant Lentiviruses (SRLV) in the Korça district emphasize the need for monitoring and controlling SRLV infection in sheep and goats. According to the study’s conclusions, a yearly monitoring program is essential and must be developed in the future to keep the disease under control. This initiative aims to help owners understand SRLV and the need to raise seronegative animals

The genetic variability of small-ruminant lentiviruses and its impact on tropism, the development of diagnostic tests and vaccines and the effectiveness of control programmes.

Maedi-visna virus and caprine arthritis encephalitis virus are two closely related lentiviruses which cause multisystemic, progressive and persistent infection in goats and sheep. Because these viruses frequently cross the species barrier, they are considered to be one genetic group called small-ruminant lentiviruses (SRLV). They have in vivo tropism mainly for monocytes and macrophages and organ tropism with unknown mechanisms. Typical clinical signs are pneumonia in sheep, arthritis in goats, and mastitis in both species. Infection with SRLV cannot currently be treated or prevented, and control programmes are the only approaches to avoiding its spread. These programmes rely mainly on annual serological testing and elimination of positive animals. However, the high genetic and antigenic variability of SRLV complicate their early and definitive diagnosis. The objective of this review is to summarise the current knowledge of SRLV genetic variation and its implications for tropism, the development of diagnostic tests and vaccines and the effectiveness of control and eradication programmes. Subject literature was selected from the PubMed and the Google Scholar databases. The high genetic diversity of SRLV affects the performance of diagnostic tools and therefore control programmes. For the early and definitive diagnosis of SRLV infection, a combination of serological and molecular tests is suggested. Testing by PCR can also be considered for sub-yearling animals. There are still significant gaps in our knowledge of the epidemiology, immunology and biology of SRLV and their impact on animal production and welfare. This information may aid selection of the most effective SRLV spread reduction measures.

Epizootiological serosurvey on small ruminant lentiviruses: Prevalence, age and breed effects

AbstractIn this study, the prevalence of small ruminant lentivirus, i.e. Maedi-Visna and caprine arthritis encephalitis virus infections in sheep and goat populations were investigated through epizootiological serosurveillance in the Aegean region located in western Türkiye in 2018. A total of 1,840 serum samples (595 goats, 1,245 sheep) were collected from 92 villages in the region and examined by indirect ELISA. Thirty-nine goat and 304 sheep sera were found positive for small ruminant lentivirus antibodies. The prevalence was 24.42% in sheep and 6.55% in goats. An average of 18.64% was found in small ruminants in the Aegean region. The prevalence of small ruminant lentiviruses was found to be higher in Pirlak and Pirlak hybrid sheep and in Saanen and Saanen hybrid goats (P < 0.05). The prevalence was found to increase with age, as it was higher in animals older than 48 months than in the age groups of 0–24 or 25–48 months (P < 0.05). Moreover, the small ruminant lentivirus prevalence was higher in sheep than in goats (P < 0.0001). With the epizootiological approach, this study is expected to contribute to the control and prevention of small ruminant lentivirus infections.

Caprine arthritis encephalitis virus-induced apoptosis associated with brain lesions in naturally infected kids

Acute demyelinating leucoencephalomyelitis was the most conspicuous microscopic change in the brain and spinal cord of kids infected with caprine arthritis encephalitis virus (CAEV). TUNEL positivity and labelling of anti-bax and anti-caspases-3, -8 and -9 were found in a distinct population of glial cells, mainly at the edges of the demyelinated plaques and perivascular areas and, to a lesser extent, in neurons. Double labelling revealed that most of these apoptotic cells in the demyelinated plaques were astrocytes and a few were oligodendroglia. In contrast, expression of bcl-2, an anti-apoptotic protein, was found mainly in neurons of the brainstem and cerebellum and motor neurons of the spinal cord, but was restricted in glial cells. These results suggest that apoptosis plays an important role in the pathogenesis of CAE demyelinating encephalitis.

Isolation and Identification of Caprine Arthritis Encephalitis Virus from Animals in the Republic of Mordovia.

This article presents the results of virological and genetic studies of an isolate of caprine arthritis encephalitis (CAE) virus from the republic of Mordovia, Russian Federation. The isolate was found during monitoring studies of goat blood samples for the viral genome, and the presence of antibodies to lentiviruses was detected. According to the recommendation of the OIE, the positive result of PCR was confirmed with nucleotide sequencing. It was found that the obtained nucleotide sequence is identical to the genome of small ruminant lentiviruses presented in the GenBank database. Phylogenetic analysis showed that the isolate "Mordovia-2018" was included in the same cluster with an isolate from the Tver region of the Russian Federation detected in 2008. The sequence of the fragment of the env-gene of the isolate from the republic of Mordovia is available in GenBank under the number MN186380.1. To isolate the virus, a fraction of peripheral blood monocyte cells from the animal's blood was added to a monolayer of lamb synovial membrane cell culture, and ten passages were carried out. The first manifestations of the cytopathic effect were observed after the third passage on the eighth day of cultivation in the form of single large cells of irregular shape with 5-7 nuclei. At the seventh passage, multiple syncytium with 7-12 nuclei were observed. At subsequent passage levels, the formation of syncytium containing more than 10-14 nuclei was observed.

Multiplex assay for the simultaneous detection of antibodies against small ruminant lentivirus, Mycobacterium avium subsp. paratuberculosis, and Brucella melitensis in goats.

Brucellosis, paratuberculosis (PTb), and infections caused by small ruminant lentivirus (SRLV), formerly known as caprine arthritis encephalitis virus (CAEV), adversely affect goat production systems. Nonetheless, commonly used diagnostic tests can only determine one analyte at a time, increasing disease surveillance costs, and limiting their routine use. This study aimed to design and validate a multiplex assay for antibody detection against these three diseases simultaneously. Two recombinant proteins from the SRLV (p16 and gp38), the native hapten of Brucella melitensis, and the paratuberculosis-protoplasmic antigen 3 from Mycobacterium avium subsp. paratuberculosis (MAP) were used to devise and assess a multiplex assay. Conditions for the Luminex® multiplex test were established and validated by sensitivity, specificity, repeatability, and reproducibility parameters. Cut-off points for each antigen were also established. The 3-plex assay had high sensitivity (84%) and specificity (95%). The maximum coefficients of variation were 23.8% and 20.5% for negative and positive control samples, respectively. The p16 and gp38 SRLV antigens are 97% and 95%, similar to the CAEV sequence found in GenBank, respectively. The multiplex test can be effectively used for the simultaneous detection of antibodies against SRLV, MAP and B. melitensis in goats.

O-117 Follow-up scenario’s, including retrospective bulk milk testing, after loss of caprine arthritis encephalitis virus (CAEV) herd accreditation in commercial dairy goat farms

O-117 Follow-up scenario’s, including retrospective bulk milk testing, after loss of caprine arthritis encephalitis virus (CAEV) herd accreditation in commercial dairy goat farms

Serological testing of an equal-volume milk sample – a new method to estimate the seroprevalence of small ruminant lentivirus infection?

BackgroundIn cattle attempts to evaluate within-herd prevalence of various infectious and parasitic diseases by bulk-tank milk (BTM) testing with ELISA have been made with moderate success. The fact that BTM is composed of variable and unknown volumes of milk from individual lactating animals weakens the relationship between numerical result of the ELISA and the within-herd prevalence. We carried out a laboratory experimental study to evaluate if a pooled milk sample created by mixing an equal volume of individual milk samples from seropositive and seronegative goats, henceforth referred to as an equal-volume milk sample (EVMS), would allow for accurate estimation of within-herd seroprevalence of caprine arthritis-encephalitis (CAE) using 3 different commercial ELISAs. By mixing randomly selected milk samples from seronegative and seropositive goats, 193 EVMS were created – 93 made of seronegative samples and 100 with the proportion of seropositive individual milk samples (EVMS%POS) ranging from 1 to 100%. EVMS%POS could be considered as a proxy for the within-herd seroprevalence. Then, OD of EVMS (ODEVMS) of the 193 EVMS was measured using 3 commercial ELISAs for CAE – 2 indirect and 1 competitive.ResultsThe cut-off values of ODEVMS indicating SRLV infection were determined. The regression functions were developed to link ODEVMS with EVMS%POS. A significant monotonic relationship between ODEVMS measured with 2 commercial indirect ELISAs and EVMS%POS was identified. Two regression models developed on this basis described approximately 90% of variability and allowed to estimate EVMS%POS, when it was below 50%. High ODEVMS indicated EVMS%POS of > 50%.ConclusionOur study introduces the concept of serological testing of EVMS as a method of detecting SRLV-infected herds and estimating the proportion of strongly seropositive goats. Further field studies are warranted to assess practical benefits of EVMS serological testing.

A Combined Approach for Detection of Ovine Small Ruminant Retrovirus Co-Infections.

Jaagsiekte retrovirus (JSRV)-induced ovine pulmonary adenocarcinoma (OPA) is an important ovine respiratory disease in Switzerland. Furthermore, ovine lungs with OPA frequently exhibited lesions suggestive of maedi-visna virus (MVV) or caprine arthritis encephalitis virus (CAEV) infection, indicating that co-morbidities might occur. Lungs and pulmonary lymph nodes were sampled from suspected OPA cases, inflammatory lung lesions and control lungs (total of 110 cases). Tissues were (a) processed for histology and immunohistochemistry (IHC), and (b) underwent DNA extraction and real-time PCR for JSRV, MVV and CAEV. Peptide sequences were used to generate virus-specific customized polyclonal antibodies. PCR-positive OPA cases and formalin-fixed and paraffin-embedded MVV- and CAEV-infected synovial cell pellets served as positive controls. Fifty-two lungs were histologically diagnosed with OPA. Histological evidence of MVV/CAEV infection was detected in 25 lungs. JSRV was detected by PCR in 84% of the suspected OPA cases; six were co-infected with MVV and one with CAEV. MVV was detected by PCR in 14 cases, and four lungs were positive for CAEV. Three lungs had MVV/CAEV co-infection. In IHC, JSRV was detected in 91% of the PCR-positive cases, whereas MVV and CAEV immunoreactivity was seen in all PCR-positive lungs. Although PCR showed a higher sensitivity compared to IHC, the combined approach allows for investigations on viral cell tropism and pathogenic processes in co-morbidities, including their potential interdependency. Furthermore, an immunohistochemical tool for specific differentiation of MVV and/or CAEV infection was implemented.