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Simple Summary: Small ruminant lentiviruses (SRLVs) are responsible for a disease complex that includes a variety of clinical forms with a large degree of severity. The virus is highly variable, and 5 genotypes with 34 subgenotypes have been described so far. However, the application of different protocols for genotyping generated contradictory results with potential misclassification of some strains and/or identification of redundant new subgenotypes. To the best of our knowledge, no systematic review on the molecular characterization of SRLVs in sheep and goats is available. The present systematic review aims to provide an updated, in-depth, comprehensive overview of the phylogenesis of SRLVs. The systematic review was developed according to the PRISMA-P statement. Small ruminant lentiviruses (SRLVs) are responsible for chronic and progressive multisystemic clinical forms, which significantly reduce flocks' productivity and have a considerable economic impact on the small ruminant industry. Due to the increase in genetic analysis studies and the potential for misclassification of certain strains, owing to the high genetic variability of these viruses, a systematic review was deemed necessary. This review explores the types of matrices used for molecular detection and phylogenetic studies, the genomic regions selected as targets, and the software utilized for phylogenetic analysis, assessing the geographical distribution of identified genotypes and subgenotypes over time. A thorough comparison of the diagnostic approaches highlights the strengths and limitations of each method, identifying gaps that need to be addressed. Additionally, recombination events and compartmentalization are examined to provide an updated, detailed, and comprehensive overview of SRLV phylogenesis. [ABSTRACT FROM AUTHOR]

Ovine pulmonary adenocarcinoma (OPA) is an important viral-induced neoplasia in sheep caused by exogenous Jaagsiekte sheep retrovirus (exJSRV). Coinfection of exJSRV and Maedi-Visna virus (MVV) is reported in OPA cases, but its worldwide distribution and significance on lung pathology is not yet completely understood. This study aimed to investigate the MVV coinfection rate in 82 exJSRV-related OPA cases, and their pathological effects on lung parenchyma in slaughtered sheep in Transylvania (Romania). On gross examination, classical form of OPA was identified in 92.7%; no changes consisting with MVV interstitial pneumonia were identified in the included cases. The most common histological type of OPA was acinar (58.5%) and the myxoid growths were found in 18 cases. The exJSRV and MMV coinfection rate in examined sheep was 47.6% (39/82). The assessment of perineoplastic areas from coinfected animals, revealed interstitial lymphoplasmacytic infiltrates in all cases, lymphoid hyperplasia in 60.6% cases (20/33) and fibromuscular hyperplasia in 63.7% (21/33). This is the first report providing new data on distribution of OPA coexisting with MVV infection in slaughtered sheep in Romania. We consider that the OPA and MVV coinfection may play an important role on the severity of ovine chronic pulmonary diseases and further studies are needed to confirm this hypothesis. [ABSTRACT FROM AUTHOR]

Maedi-Visna is a slowly progressive infection of sheep that affects the respiratory and nervous systems and causes significant yield losses worldwide. This study was conducted to assess the seroprevalence of Maedi-Visna infection in sheep across several provinces in the Central Black Sea region of Türkiye, namely Samsun, Sinop, Ordu, Giresun, Amasya and Tokat. A total of 476 sheep serum samples were collected for further analysis. The presence of antibodies in the sera was determined by Ab ELISA. As a result of the study, 263 (55.25%) blood serum samples were positive for the presence of MVV antibodies. Seropositivity rates by province were as follows: Samsun 45%, Sinop 80%, Ordu 58.75%, Giresun 35%, Amasya 38.75%, Tokat 75%. Notably, our findings suggest a significantly high seroprevalence of Maedi-Visna infection in this region compared to other studies conducted in different parts of Türkiye This information is pivotal for understanding the extent of the infection in the sheep population of the Central Black Sea region and can contribute to the development of strategies for disease management and control. [ABSTRACT FROM AUTHOR]

Background: Maedi-visna (MV) is a small ruminant lentiviral (SRLV) disease affecting sheep and goats, and causes pathological alterations in various organs including lungs, pulmonary lymph nodes, mammary glands, joints, and CNS. Aims: Present study was focused to detect the MV virus (MVV) nucleic acid and MVV p28 antigen in different organs of the spontaneously MVV affected sheep and goats. Methods: Total of 657 samples were collected from sheep and goats (169 blood, 136 lungs, 96 pulmonary lymph nodes, 74 brain, 54 mammary gland, 78 joints, and 50 spleen) and screened for MVV nucleic acid using nested PCR assay. Serum samples were screened for SRLV antibodies by cELISA. Immunolocalization of MVV was demonstrated by using the polyclonal antibody against p28 antigen by immunohistochemistry in lungs, lymph nodes, mammary glands, and joint tissues. Results: Out of 657 samples, 10.7% (70) were found positive for MVV. Among different organs, lungs showed highest positivity (25.7%) followed by mammary glands (14.8%), blood (9.5%), joint tissues (7.7%), brain (5.4%), and pulmonary lymph node (1.0%). SRLV antibodies were detected in 29.2% of the serum samples of both sheep and goats by cELISA. MVV p28 antigen immunostaining was observed in lungs, lymph nodes, mammary glands, and joint tissues. However, the presence of MVV p28 antigen could not be demonstrated in the brain tissues. Conclusion: The highest positivity of MVV in lung tissues indicated higher predilection of the virus in the pulmonary tissue. [ABSTRACT FROM AUTHOR]

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% Confidence Interval (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 (Odds Ratio (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 and 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. [ABSTRACT FROM AUTHOR]

Small ruminant lentiviruses (SRLVs) pose significant economic challenges to goat farming and have a detrimental impact on animal welfare. The objectives of this study were to deepen our comprehension of SRLV infections and their implications for small ruminant farming. Within the studied herd, the detected seroprevalence of SRLV was notably high at 91.92% (95.0% CI: 86.5%-97.3%). This finding strongly suggests the enduring presence of SRLV infection within the goat farm, spanning multiple years. Antibodies against SRLVs were detected across all selected age categories and breeds, irrespective of the presence or absence of clinical signs. The data gleaned from this study allow significant implications, raising concerns about the potential for future clinical outbreaks resulting from SRLV infections in eastern Romanian goat herds. Given these findings, the imperative for the continuous surveillance of SRLV infections becomes evident. Ongoing vigilance and monitoring are essential to mitigate the risk of disease transmission, minimise economic losses and safeguard the welfare of goats within the region. [ABSTRACT FROM AUTHOR]

Simple Summary: Maedi-visna is a globally distributed, viral, and incurable chronic disease of small ruminants, challenging the health and welfare of sheep and jeopardizing the sustainability of farms. Currently, the scarcity of representative, updated, and epidemiological data hinders the implementation of successful eradication programs. The objective of our study is to prospectively study the seroepidemiology of maedi-visna in intensively reared dairy sheep. For this reason, a total of 407 purebred Chios and Lacaune ewes from four farms were studied for two successive years, and blood samples were semiannually collected and tested using the ELISA test. Prevalence and incidence rates were found to have increased in all the studied farms, highlighting the importance of horizontal transmission of the virus within the farms. Various serological patterns were observed in the studied animals, namely, constantly seronegative, constantly seropositive, seroconverted, seroreverted, or animals with an intermittent presence of antibodies. The last two categories indicate a special immune response of infected animals which needs to be further investigated and considered for the diagnosis of MV and when designing eradication programs. 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. [ABSTRACT FROM AUTHOR]

Small ruminant lentiviruses (SRLVs) affect sheep and goats worldwide. The major gene related to SRLV infections is the Transmembrane Protein Gene 154 (TMEM154). We estimated the haplotype frequencies of TMEM154 in the USA (USDA-ARS) and Brazil (Embrapa) Gene Banks by using two different SNP genotyping methodologies, FluidigmTM and KASPTM. We also genotyped the ZNF389_ss748775100 deletion variant in Brazilian flocks. A total of 1040 blood samples and 112 semen samples from 15 Brazilian breeds were genotyped with Fluidigm for the SNP ZNF389_ss748775100 and 12 TMEM154 SNPs. A total of 484 blood samples from the Santa Inês breed and 188 semen samples from 14 North American sheep breeds were genotyped with KASP for 6 TMEM154 SNPs. All the Brazilian samples had the "I/I" genotype for the ZNF389_ss748775100 mutation. There were 25 TMEM154 haplotypes distributed across the Brazilian breeds, and 4 haplotypes in the US breeds. Haplotypes associated with susceptibility were present in almost all breeds, which suggests that genetic testing can help to improve herd health and productivity by selecting non-susceptible animals as founders of the next generations. Fluidigm and KASP are reliable assays when compared with Beadchip arrays. Further studies are necessary to understand the unknown role of TMEM154 mutations, host–pathogen interaction and new genes associated with the clinical condition. [ABSTRACT FROM AUTHOR]

Maedi-visna is a multi-systemic disease of sheep caused by a non-oncogenic, exogenous retrovirus of the Lentiviridae subfamily. It is mainly transmitted through the ingestion of milk from infected sheep, although disease can be spread within flocks through direct contact and transmission can occur also in utero. Maedi usually begins insidiously and leads to a classical interstitial pneumonia. On postmortem examination, the lungs may be 2-4 times heavier than normal, due to decreased elasticity and fibrosis. Regional lymph nodes are enlarged with formation of lymphoid follicles with active germinal centers. Visna - the neurological form of the disease, is characterized by chronic and active meningoencephalomyelitis and chorioiditis with massive infiltrations of mononuclear cells around the blood vessels, microglial nodules formation and astrogliosis. Virus isolation is very specific but of variable sensitivity. The cytopathic effects are characteristic, consisting of the appearance of stellate cells and syncytia. The diagnostic methods currently used are based on the detection of either antibodies or the viral genome. The three most commonly tests used, are the PCR and RT-PCR, agar gel immunodiffusion test (AGID) and the enzyme-linked immunosorbent assay (ELISA). Western blot analysis and radio-immunoprecipitation are also performed, but only in specialized laboratories. No commercial vaccines are available to control infection, and to date, monitoring programs have proved to be the only effective tool in controlling this disease. [ABSTRACT FROM AUTHOR]

Simple Summary: Local breeds represent a precious reservoir of genetic diversity, crucial to adapting to environmental and climate changes and reacting to evolving diseases. In Sicily, four native dairy breeds, namely Valle del Belìce, Comisana, Barbaresca, and Pinzirita, have adapted to low-input farming systems and semiarid environments, having an essential role in producing high-quality milk and typical dairy products. Maedi-visna (MV) is one of the most important chronic diseases affecting the sheep sector worldwide, causing production losses. Different target genes play an important role in immunity and in genetic resilience to MV, such as TMEM154, TLR9, MYD88, and CCR5. A major host genetic component to sheep MV susceptibility was identified in the ovine TMEM154 gene. Animals with either of TMEM154 haplotypes that encode glutamate at position 35 (E35) of the protein are at higher risk of MV infection than those homozygous with lysine at position 35 (K35). In the tested Sicilian breeds, animals carrying the allele E35 showed a greater risk of being serologically positive. Comisana, Barbaresca, and Pinzirita breeds showed a good frequency of the protective allele K35, whilst a high frequency of risk allele was found in the Valle del Belìce breed, related to the selection strategies addressed to obtain a productive dairy sheep. Our results highlight the importance of the preservation of autochthonous breeds as a reservoir of natural resistance against infectious disease. Maedi-visna (MV) is a disease caused by small ruminant lentiviruses. It is included in the list of notifiable terrestrial animal diseases due to economic losses and animal welfare harm in the sheep sector. To date, control programs remain the onliest approach to avoiding infection. The allelic variant p.Glu35Lys (E35K) of the TMEM154 gene has been strongly associated with host vulnerability to MV illness. The present study aimed to investigate the association of TMEM154 E35K allele frequencies with MV susceptibility in native Sicilian sheep breeds. More than 400 animals from 14 local sheep were serologically tested and genotyped for the TMEM154 E35K polymorphism. The local breeds displayed different values of MV seroprevalence, with the lowest antibody prevalence in Barbaresca and Pinzirita breeds. TMEM154 protective allele (K35) was less frequent than the risk allele (E35) in Valle del Belìce breed, whereas the other three breeds showed a more balanced alleles distribution. A positive association between seroprevalence and genotype was found in the entire sample set. The risk of infection resulted in more than 3-fold times as high in sheep with EK and EE genotype compared to the KK genotype. Our data could be helpful in establishing selection breeding programs aimed at reducing MV infection in Sicilian sheep farming and encouraging the breeding of native breeds. [ABSTRACT FROM AUTHOR]

The results of previous studies of SRLV infections in wild ruminants suggest that wild ruminants may serve as virus reservoirs responsible for the infections of domestic small ruminants. It is possible that SRLVs circulate in free-ranging mouflons in Slovenia, but considering the results of previous studies in which SRLV infections were detected in mouflons, it is very likely that the detected seropositive animal is an accidental spillover host for SRLV. Keywords: small ruminant lentiviruses; SRLV; maedi-visna; caprine arthritis-encephalitis; chamois; mouflon; serology; ELISA; survey EN small ruminant lentiviruses SRLV maedi-visna caprine arthritis-encephalitis chamois mouflon serology ELISA survey N.PAG N.PAG 6 04/26/22 20220415 NES 220415 1. [Extracted from the article]

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Copyright of Eurasian Journal of Veterinary Sciences is the property of Eurasian Journal of Veterinary Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Maedi-Visna (MV) is a progressive lymphoproliferative viral disease that affects multiple organs of small ruminants, including sheep and goats. The disease occurs primarily in the lung tissue and causes interstitial pneumonia. Aims: The aim of present study was to investigate the prevalence of ovine MV infection in Iranian sheep population through macroscopic, histopathological, serological, and molecular assays, as well as transmission electron microscopy (TEM). Methods: Lung and blood samples of one-hundred female sheep (≤ 2 years old) referred to the Kermanshah slaughterhouse with respiratory symptoms were collected for histopathological and molecular evaluations. Corresponding serum samples were also collected for serological examination. Results: Histopathological study showed the Maedi-like pulmonary lesions in 85% of the affected lungs, which included the interstitial pneumonia, smooth muscle hypertrophy of alveolar septa and around the blood vessels, interstitial lymphoplasmacytic infiltration and lymphofollicular hyperplasia. Specific antibodies against MV virus were detected in 7% of serum samples. Long terminal repeat (LTR) region of MV provirus was amplified in three (3%) DNA samples, extracted from the suspected lungs. Sequencing analysis of polymerase chain reaction (PCR)-positive samples confirmed the presence of MV provirus in the genome. No amplification was observed, neither in the DNA samples extracted from the blood samples of suspected sheep nor the control group. Transmission electron microscopy also confirmed the presence of MV virions inside the cytoplasmic membrane of MV-infected macrophages. Conclusion: Although histopathology can provide a preliminary estimation of Maedi in populations, definitive diagnosis of the disease needs to be approved by more sensitive techniques such as serological examinations and molecular analysis. [ABSTRACT FROM AUTHOR]

Copyright of Kafkas Universitesi Veteriner Fakultesi Dergisi is the property of University of Kafkas, Faculty of Veterinary Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Ataturk University Journal of Veterinary Sciences is the property of Ataturk University Coordinatorship of Scientific Journals and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Brasileira de Saúde e Produção Animal (RBSPA) is the property of Revista Brasileira de Saude e Producao Animal (RBSPA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The study was conducted with the objectives of determining the possible causes of pneumonia in the sheep and to characterize the microscopic lesions of concurrent infection of Maedi-Visna with lung worms and other infectious pneumonia. Detailed gross and microscopic examinations were employed on 35 Maedi-Visna seropositive sheep. Out of 35 sheep slaughtered and examined for gross lesions on their lungs, lung worms, fibrinous adhesions, and mottling on the cranioventral lobes were observed with decreasing order of frequency. Histopathologically, the pneumonic lungs (n = 35) revealed Maedi (100%), Maedi-Verminous pneumonia complex (28.57%, n = 10), Maedi bronchopneumonia complex (17.14%, n = 6), and Maedi-pulmonary adenomatosis complex (2.86%, n = 1). The occurrence of high proportion of concurrent infection of Maedi-Visna with lung worms and bacteria strongly suggest synergy of the pathogens and the presence of several stress factors including wind draft, unusually chilly weather and poor management in the area that are known to predispose the improved sheep breeds to respiratory disease complex. On top of culling by slaughter of Maedi-Visna seropositive sheep, regular deworming, redesigning the house, and vaccination of sheep with the available vaccines should be carried out timely at least to reduce the severity of Maedi-Visna induced loss. [ABSTRACT FROM AUTHOR]

In 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. [ABSTRACT FROM AUTHOR]

Maedi-Visna (MV) and Caprine Arthritis Encephalitis (CAE) are diseases of sheep and goats. They are caused by lentiviruses which belong to Retroviridae family. The usual way of contamination is the cohabitation of animals. Diseases are widespread in many countries as: Norway, France, Italy, Spain, USA, Panama, Cyprus, Greece, and Japan. The present paper aimed to present the MVV and CAEV antibodies seroprevalence in samples collected in different sheep and goats farms from Romania. There were collected blood samples from the following counties: ClujNapoca, Ilfov, Constanta, Galati, Giurgiu, Braila, Arges, Bacau, Dâmbovita, Ialomita, Suceava, Calarasi, Buzau, Vrancea, and Vaslui. In order to determine the presence of antibodies, the samples were analysed by indirect ELISA, using commercial kits. There were registered negative results in only four counties and the possible existence of viruses in farms cannot be excluded. In order to confirm and strengthen the preliminary results, we recommend to analyses the samples by molecular biology techniques. Also, national authorities could establish a program of surveillance and diagnosis at national level, able to provide a more complete picture of the SRLVs prevalence in each county. [ABSTRACT FROM AUTHOR]

whose pathological pattern suggest the SRLV infection was in Nederland, in 1862. Since then, several reports of clinical cases and scientific research, proved the wide dissemination of SRLV infections (Maedi-Visna in sheep and Caprine Arthritis-Encephalitis in goats) throughout all countries with large number of sheep and goats. In 1998, it was published a phylogenetic analysis of SRLV and it was proved the cross-species transmission of CAEV and MVV strains; moreover, in 2010, phylogenetic reconstructions supported the existence of SRLV cross-species transmission between domestic and wild small ruminants. SRLVs is a genetic continuum of lentiviral species (MVV, CAEV) in sheep and goats with evidence based of cross species transmission. The high genetic variability of SRLV, generate the classification of the viral genotypes into five groups and several subtypes, based on the phylogenetic analysis of two long genomic segments: the gag-pol segment (1.8 kb) and the pol segment (1.2 kb). Pathogenesis of lentiviral infections is the result of several particular factors, as the virus strain, the genetics of the host and the microenvironment. All this are influencing the tropism of lentivirus to a particular host animal or cell, tissue or organ. Till present, despite the huge and increasing speed in bio technics, the pathogenesis of SRLV infections, either in goat or in sheep, is not completely understood and the interaction of the host with those viruses is not fully known. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Multisystemic disease caused by Small Ruminant Lentiviruses (SRLV) in sheep and goats leads to production losses, to the detriment of animal health and welfare. This, together with the lack of treatments, has triggered interest in exploring different strategies of immunization to control the widely spread SRLV infection and, also, to provide a useful model for HIV vaccines. These strategies involve inactivated whole virus, subunit vaccines, DNA encoding viral proteins in the presence or absence of plasmids encoding immunological adjuvants and naturally or artificially attenuated viruses. In this review, we revisit, comprehensively, the immunization strategies against SRLV and analyze this double edged tool individually, as it may contribute to either controlling or enhancing virus replication and/or disease. [ABSTRACT FROM AUTHOR]

Background: The Maedi-Visna (MV) lentivirus causes two slowly progressive eventually fatal diseases of sheep, Maedi, a progressive interstitial pneumonia, and Visna, a progressive demyelinating disease of the central nervous system. Other lentiviruses also cause fatal slow infections in their natural hosts, e.g. the HIV virus in humans. Results of experimental vaccination against any lentivirus where vaccinees are challenged by natural routes, may therefore be of general interest. From 1991-1998 experiments with formalin-inactivated whole Maedi-Visna virus vaccine were carried out in the Department of Microbiology at the University of Iceland. Western Blot tests showed good immune response to all major proteins of the virus. When aluminium hydroxide was added to the vaccine all vaccinees developed neutralizing antibodies to the vaccine strain at titers 1/8 - 1/256. After housing 5 twin pairs, one twin in each pair vaccinated, the other unvaccinated, with infected sheep for 4 years, all the unvaccinated twins became infected, but only 2 of their vaccinated siblings as confirmed by virus cultivation experiments on tissues from their lungs spleens lymph nodes and choroid plexuses. Results: One twin in each of 40 female twin pairs, born into a Maedi-Visna-infected sheep flock and kept under natural farming conditions in Cyprus, was vaccinated at birth, 3 weeks and 3 months, with formalin-inactivated whole Maedi-Visna lentivirus vaccine adjuvanted with aluminium hydroxide. 17 mothers of the twins were seronegative, 13 seroconverting and 10 had old infection. Of 17 vaccinees born to seronegative mothers 9 were uninfected at 28 months, but only 2 of their unvaccinated siblings. Of 13 unvaccinated twins born to seroconverting mothers, 12 caught infection during their first 10 weeks, but only 4 of their vaccinated siblings. Vaccination had no effects on 10 vaccinees born to mothers with long-standing Maedi-Visna infections and broad andibody response at birth of their lambs. Conclusion: Compared with their unvaccinated siblings, natural infection was delayed in significant number of vaccinated twins born by seronegative and seroconverting mothers and vaccinated at birth, 3 weeks and 3 months with formalin inactivated whole MV vaccine adjuvanted with aluminium hydroxide. Maternal antibodies interfered with vaccination so early in life if the mother had old infection. [ABSTRACT FROM AUTHOR]

Maedi-visna (MV) is an important slow viral disease of sheep leading to a progressive lymphoproliferative disease. It affects multiple organs primarily the lungs, where it causes interstitial pneumonia (maedi). In this study, the lungs of 1,000 sheep carcasses were grossly inspected and those suspected to have maedi were studied at histopathological and molecular levels. A polymerase chain reaction (PCR) technique that amplified a 291-base pair DNA in the long terminal repeat (LTR) sequence of MV provirus was conducted on all the 50 suspected lungs together with 10 normal appearing lungs as controls. Amplicons of the expected size were detected in 11 ( n = 11/50) suspected sheep, and one of the 10 control sheep. Histopathologic study of the pulmonary lesions of all 11 ( n = 11/11) positive sheep showed MV lesions, including hyperplasia of the perivascular and peribronchiolar lymphoid cells, interstitial lymphoplasmacytic infiltration and smooth muscle hyperplasia and the histopathologic findings were correlated with PCR results. In contrast, the tissue sections of control animals were almost normal at histopathological level; however, PCR technique demonstrated that one of them was affected by maedi. This study showed that the LTR-PCR had high specificity and sensitivity in diagnosis of this viral infection. This study is the first to evaluate the prevalence of MV virus infection in sheep in Iran. [ABSTRACT FROM AUTHOR]

Copyright of Veterinaria México is the property of Facultad de Medicina Veterinaria y Zootecnia UNAM and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The presence of antibodies against Maedi-Visna (MV) and caprine arthritis encephalitis (CAE) was evaluated in ovine and caprine fetuses obtained from pregnant females slaughtered in abattoirs. Sera from 54 caprine fetuses and 65 ovine fetuses were collected and evaluated by the indirect ELISA technique. Antibodies were detected in five caprine fetuses of 80 days of gestation and in four ovine fetuses of 90 to 100 days of gestation; three caprine fetuses and two ovine fetuses of 60 to 65 days of gestation were suspicious. The possibility of uterine infection with these retroviruses is confirmed, and its consequences in current disease control and eradication strategies are discussed. [ABSTRACT FROM AUTHOR]

Small Ruminant Lentiviruses - SRLV (Caprine Arthritis - encephalitis - CAE and Maedi-Visna) infections are characterized by slow and progressive course, in which the majority of the animals do not present symptoms. Thus, the serological tests are the most practical diagnostic tool as the presence of antibodies indirectly indicates SRLV infection. This work was carried out with the objective of evaluating an agar gel micro-immunodifusion (micro-AGID) test in comparison with a macro-AGID test to be used in the serological diagnostic of SRLV in goats. In the micro- AGID, 10 µL of antigen and control serum and 30 µL of test serum were used; in the macro-AGID, 20 µL of sera and antigen were used. The tests were compared through the adjusted agreement index (Kappa - k) calculated according to 447 samples of goat serum from Pernambuco, Paraíba and Rio Grande do Norte states. Of 447 samples, 63 (14.09%) and 60 (13.42%) were positive to micro-AGID and macro-AGID, respectively, corresponding to a significant agreement between the tests (k = 0.90). Furthermore, the micro-AGID presented clearer lines than the macro-AGID and the results may be recorded 24 earlier in micro-AGID. Thus, the micro-AGID may replace the macro-AGID in the serological SRL diagnosis. [ABSTRACT FROM AUTHOR]

Microscopic examination of pneumonic lungs of the Ethiopian highland sheep ( n = 35) was made and compared with the pneumonic lungs from ten sheep and 66 goats from the lowlands. Lesions compatible with sheep pulmonary adenomatosis (SPA; 8/35, 22.8%), and maedi-visna (MV; 9/35, 25.7%) were recorded only in sheep from the central highlands. Interstitial pneumonia (43.2%), bronchopneumonia (35.1%), and verminous pneumonia (6.3%) were recorded in both sheep and goats from the high- and the lowlands. SPA was documented for the first time in sheep from Ethiopia in this report. We believe that MV and SPA were introduced into Ethiopia through importation of exotic sheep. These infections should be considered in dealing with the diagnosis of respiratory diseases in all the sheep breeds in the central highlands and in the exotic and the crossbred sheep in the other parts of the country. [ABSTRACT FROM AUTHOR]

Ovine pulmonary adenocarcinoma (OPA) and Maedi–Visna (Maedi) are two chronic respiratory diseases of retroviral origin which occur worldwide. It is known that different host genetic factors influence the outcome of viral infections. To determine if variation in the Mhc-DRB1 gene was associated with progression to these ovine diseases, sheep lungs with and without OPA and Maedi lesions were collected. A sequence-based method was applied and 40 different alleles were detected in the sample analysed. In the allele-by-allele association analysis, allele DRB1*0325 had a significant association with susceptibility to Maedi ( P = 0.045). For OPA, DRB1*0143 and DRB1*0323 were significantly associated with susceptibility ( P = 0.024 and P = 0.029), and allele DRB1*0702 was significantly associated with resistance ( P = 0.012). Based on these results, the Mhc- DRB1 alleles were classified by effect in three categories—susceptible (S), resistant (R) and neutral (N)—and animals were reassigned the genotypes as S/S, S/R, S/N, R/R, R/N and N/N. In a second analysis, penalised logistic regression models including a flock effect were run. In Maedi, significant association was detected for the N/S heterozygote ( P = 0.0007), but not for the S/S homozygote, probably as a result of the low number of S/S animals. In OPA, association was detected for both the S/S and R/R homozygotes ( P = 0.005 and P = 0.047). This allele grouping method may be applied in association studies with highly variable genes. This is the first study demonstrating significant associations between sheep Mhc- DRB1 alleles and susceptibility to OPA and Maedi. Therefore, both diseases are suitable candidates for more comprehensive genetic studies. [ABSTRACT FROM AUTHOR]

Background: Bronchoalveolar lavage has proven helpful for the diagnosis of certain ovine diseases of the lungs. There is insufficient data concerning the leukocyte profile of bronchoalveolar lavage fluid (BALF) from MaediVisna infected sheep. Objective: The objective of this study was to assess the differential leukocyte profile of BALF associated with Maedi virus infection in sheep and to determine whether cytologic examination of BALF is an effective way to diagnose Maedi or determine the severity of lung lesions. Methods: BALF and serum samples were analyzed from 400 sheep. Sediment smears of bronchoalveolar lavage were stained with Diff-Quik and examined microscopically to obtain a 200-cell differential cell count. Serum was tested using a commercial kit for Maedi–Visna virus antibodies. Lung samples obtained at the time of slaughter were weighed and examined histologically. Results: Maedi-infected sheep ( n=267; seropositive with lung lesions) had a significantly higher percentage of lymphocytes and lower percentage of macrophages in BALF than normal sheep ( n=133; seronegative and no lung lesions). These differences were significantly more severe in animals with advanced vs moderate lung lesions. Using classification trees, a cut-off of 13.5% lymphocytes was predictive of Maedi infection and a cut-off of 24.5% lymphocytes was predictive of advanced lung lesions. Conclusions: Cytologic examination of BALF is useful for the clinical diagnosis of Maedi in sheep and provides important information about the severity of the lung lesions. [ABSTRACT FROM AUTHOR]

Small ruminant lentiviruses (SRLVs), i.e., CAEV and MVV, cause insidious infections with life-long persistence and a slowly progressive disease, impairing both animal welfare and productivity in affected herds. The complex diagnosis of SRLVs currently combines serological methods including whole-virus and peptide-based ELISAs and Immunoblot. To improve the current diagnostic protocol, we analyzed 290 sera of animals originating from different European countries in parallel with three commercial screening ELISAs, Immunoblot as a confirmatory assay and five SU5 peptide ELISAs for genotype differentiation. A newly developed nested real-time PCR was carried out for the detection and genotype differentiation of the virus. Using a heat-map display of the combined results, the drawbacks of the current techniques were graphically visualized and quantified. The immunoblot and the SU5-ELISAs exhibited either unsatisfactory sensitivity or insufficient reliability in the differentiation of the causative viral genotype, respectively. The new truth standard was the concordance of the results of two out of three screening ELISAs and the PCR results for serologically false negative samples along with genotype differentiation. Whole-virus antigen-based ELISA showed the highest sensitivity (92.2%) and specificity (98.9%) among the screening tests, whereas PCR exhibited a sensitivity of 75%. [ABSTRACT FROM AUTHOR]

Small ruminant lentiviruses (SRLVs) infections lead to chronic diseases and remarkable economic losses undermining health and welfare of animals and the sustainability of farms. Early and definite diagnosis of SRLVs infections is the cornerstone for any control and eradication efforts; however, a "gold standard" test and/or diagnostic protocols with extensive applicability have yet to be developed. The main challenges preventing the development of a universally accepted diagnostic tool with sufficient sensitivity, specificity, and accuracy to be integrated in SRLVs control programs are the genetic variability of SRLVs associated with mutations, recombination, and cross-species transmission and the peculiarities of small ruminants' humoral immune response regarding late seroconversion, as well as intermittent and epitope-specific antibody production. The objectives of this review paper were to summarize the available serological and molecular assays for the diagnosis of SRLVs, to highlight their diagnostic performance emphasizing on advantages and drawbacks of their application, and to discuss current and future perspectives, challenges, limitations and impacts regarding the development of reliable and efficient tools for the diagnosis of SRLVs infections. [ABSTRACT FROM AUTHOR]

The effects of ovine lentivirus infection on the fat, protein and lactose concentrations on the somatic cell counts in ewes' milk, on milk production and on the birth weight and growth of lambs were studied in a flock of Sardinian sheep from central Italy. Data on 61 lactations of ewes positive to both the agar-gel immunodiffusion test and an enzyme-linked immunosorbent assay were compared with those on 46 lactations of seronegative ewes. Confounders such as parity, age, lactation length, litter size, and the sex of the lambs were considered. None of these traits seemed to be negatively influenced by the infection [ABSTRACT FROM AUTHOR]

Over a period of five years, the epidemiology of maedi-visna virus (MVV) infection was studied by means of sequential serological examinations in a small flock of Texel sheep after the introduction of two infected ewes. The flock was managed as an average field flock except that seropositive sheep were kept in the flock as long as possible and that replacements were preferentially selected from progeny of seropositive ewes. The first seroconversion was observed after 11 months and was soon followed by three others. A year later, a considerable increase in the number of seropositives was observed and at the end of the experiment 20 of a total of 24 sheep (83.3%) had seroconverted. A total of 16 sheep were present in the flock during the whole study, of which 13 (81.3%) had become infected by horizontal transmission. Two sheep showed a clear but transient, and another sheep showed a weak and irregular seroresponse, whereas MV-lesions proved to be present. When the flock was slaughtered, the mean age of the sheep was 5.25 years. Only a few sheep showed poor bodily condition; no other conspicuous clinical signs were observed. Nevertheless, a total of 70% of the infected sheep had maedi-visna lesions in udder and/or lungs. Udder lesions were found in 78.6%, lung lesions in 42.9% and lesions in both organs were found in 21.4% of the affected sheep. The seronegative sheep were free of lesions. No arthritic lesions were found. A total of 22 fetuses from 13 seropositive ewes were virologically examined and none yielded MVV. Zusammenfassung Fünfjährige serologische Studie über die natürliche Verbreitung von Maedi-Visna-Virus in einer Schafherde, vervollständigt durch post mortem-Untersuchung Die Epidemiologie der Maedi-Visna-Virus-Infektion (MVV) wurde über einen Zeitraum von fünf Jahren durch sequentielle serologische Untersuchungen an einer kleinen Texel-Schafherde verfolgt, in welche zwei infizierte Mutterschafe eingebracht worden waren. Die Herde wurde als Durchschnitts-Feldherde geführt, mit Ausnahme der Tatsache, daß seropositive Schafe möglichst lange in der Herde belassen wurden, und daß Ersatz bevorzugt aus der Nachzucht seropositiver Muttertiere gestellt wurde. Die erste Serokonversion wurde nach elf Monaten beobachtet und war bald von drei weiteren gefolgt. Ein Jahr später ließ sich ein beachtlicher Anstieg der seropositiven Tiere erkennen, und am Ende des Experiments waren bei 20 von insgesamt 24 Schafen (83,3%) Antikörpertiter feststellbar. 16 Schafe waren während der gesamten Studie in der Herde, von diesen wurden 13 (81,3%) durch horizontale Verbreitung infiziert. Zwei Schafe zeigten eine deutliche, aber nur vorübergehende Serumantwort. Die eines anderen Tieres war schwach und unregelmäßig, außerdem traten Maedivirus-Läsionen auf. Nach der Schlachtung der Herde lag das Durchschnittsalter der Tiere bei 5,25 Jahren. Nur wenige Schafe zeigten schlechte körperliche Verfassung; andere auffällige klinische Symptome wurden nicht beobachtet. Dennoch hatten 70% der infizierten Tiere Maedi-Visna-Läsionen im Euter und/oder Lungen. Bei den betroffenen Tieren wurden Euterläsionen in 78,6%, Lungenläsionen in 42,9% und Läsionen beider Organe in 21,4% der Fälle gefunden. Seronegative Schafe waren frei von Läsionen. Arthritische Veränderungen wurden nicht beobachtet. Von insgesamt 22 virologisch untersuchten Feten, von 13 seropositiven Mutterschafen, enthielt keiner MVV. [ABSTRACT FROM AUTHOR]

The gross and immunohistological characteristics of the purified protein derivative (PPD)-induced cutaneous DTH reaction were studied in a group of sheep naturally infected with Maedi-Visna virus (MVV), and compared with reactions obtained in a matched control group. There was a marked, but variable, depression in the DTH lesion in the MVV group associated with a decreased density of polymorphonuclear neutrophils (PMN) and CD4+ cells in the early reaction. There were no significant differences in the densities of CD8+, `γ/δ T cells, macrophages, B cells and MHC class II-expressing cells. This work indicates that there is a significant alteration in the initial trafficking of PMN and CD4+ cells into a DTH response area in sheep infected with MVV. [ABSTRACT FROM AUTHOR]

A PCR assay for the detection of small ruminant lentiviral gag DNA (provirus) in the white blood cells of sheep and goats was developed and compared with a serological test (AGIDT). A sample of the DNA prepared from the white blood cells in 3 ml of blood from 208 sheep and goats from 18 different flocks was subjected to PCR assay. One of 85 animals from flocks accredited under the Dutch national MVV/CAEV control programme was positive by PCR while none was positive by AGIDT. In infected flocks, the AGIDT appeared slightly more sensitive, but preliminary results show that the sensitivity of the PCR assay may be further improved by increasing the number of monocytes tested. The PCR assay, however, was clearly more sensitive in detecting animals in the early stages of infection. With the use of a set of mixed primers and probes, the assay was able to detect the variety of CAEV and MVV strains occurring in the field. [ABSTRACT FROM AUTHOR]

Simple Summary: Maedi-visna is a progressive wasting disease of sheep that leads to decreased animal condition and production. It is caused by Small Ruminant Lentiviruses (SRLV), single-stranded RNA viruses with high mutational potential. There is neither treatment nor vaccine against SRLV and proper diagnosis is the key element for efficient control measures against positive animals. This systematic review and meta-analysis summarizes the individual and flock prevalence of SRLV throughout the world and describes the diagnostic tests employed over the last four decades. Our results indicate that Europe is the continent with the most information on the prevalence of the infection as well as with the highest SRLV prevalence at the individual level. Flock prevalence depends directly on the individual prevalence. SRLV diagnostic methods in sheep have substantially changed during the last decades, but serologic methods have always been the most frequently used techniques for prevalence studies. A combination of at least two diagnostic tests is fully encouraged for future prevalence studies and health programs. ELISA and PCR show synergic effects in SRLV diagnosis. 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. [ABSTRACT FROM AUTHOR]

Simple Summary: There are no data on the effect of the transmembrane protein 154 (TMEM154) E35K variants on susceptibility to small ruminant lentivirus (SRLV) infection in Iranian sheep breeds, and only limited data for German sheep flocks. This study aimed at investigating the association of TMEM154 variants and SRLV infection status in Iranian and German sheep flocks and breeds. Three out of the four analyzed sheep flocks/breeds showed a significant association between TMEM154 variants and SRLV prevalence. A complementary analysis was carried out based on regression analysis to test the relationship between frequency of the TMEM154 E allele and SRLV prevalence in different flocks/breeds. Results showed that the TMEM154 E allele frequencies could be useful for predicting genetic susceptibility to SRLV infection in a sheep flock or breed. Finally, the genetic susceptibility of different Iranian and German sheep breeds was compared based on the frequency of the TMEM154 E allele. Small ruminant lentiviruses (SRLVs) cause maedi-visna disease in sheep and are prevalent in Iran and Germany. The association of the transmembrane protein 154 (TMEM154) variants with SRLV infection has been previously identified by a genome-wide association (GWAS) approach and subsequent analyses, and validated in some US, German, and Turkish sheep flocks. We aimed at evaluating these findings for the first time in Iranian, and in some more German sheep flocks/breeds. Also, we aimed at comparing the SRLV susceptibility in Iranian and German sheep based on the frequency of the TMEM154 E35 allele. About 800 blood samples were collected from 21 Iranian and German sheep flocks/breeds for different purposes: (1) The association of TMEM154 E35K with SRLV infection status was tested in four sheep breeds and found to be significant in Kermani, Merinoland, and Brown Hair. (2) The usefulness of the TMEM154 E35 frequency for predicting SRLV susceptibility was evaluated by regression analysis, combining data from this study and some already published data. Results showed a significant association between E35 frequency and SRLV prevalence. (3) SRLV susceptibility was compared based on E35 frequency in Iranian and German sheep. Altogether, findings of this study provide valuable information on SRLV susceptibility, using TMEM154 E35, in Iranian and German sheep. [ABSTRACT FROM AUTHOR]