Visna Research Articles

Investigation of the Epidemiology of Small Ruminant Lentivirus Infections southeast part of the Marmara region of Turkey

Small ruminant lentiviruses (SRLVs) are viral pathogens that are common in goats and sheep, affect production, and cause significant economic losses in small ruminant breeding. Caprine arthritis encephalitis virus (CAEV) and Maedi-Visna virus (MVV) are prototypes of SRLVs. Both of them affect animal health and welfare in sheep and goats and cause progressive and persistent infections in the small ruminant industry. The present study aimed to reveal the epidemiological status of lentivirus infection in the sheep region in Yalova province located in the southeast part of the Marmara region and determine the circulating genotypes by conducting the sequence analysis of the samples detected positive by a molecular method and molecular characterization of the detected field strains. To that end, 231 sheep blood samples were used between May 2016 and April 2018. Based on sampling results of the PCR test and ELISA tests, 5.62% (13/231) and 5.19% (12/231) positivity rates were found in sheep, respectively. According to the ELISA test results, a significant difference was found in terms of age groups (6 months -1 age, 1-3 age, >3 age) (χ2: 6.01; p=0.04). Furthermore, the sequence analysis of the gag gene region detected the existence of the A genotype of small ruminant lentiviruses in sheep. The data obtained from the study revealed a low seroprevalence course of SRLV infection in the study area in the absence of a systematic disease control program.

Structural basis for recruitment of host CypA and E3 ubiquitin ligase by maedi-visna virus Vif.

Lentiviral Vif molecules target the host antiviral APOBEC3 proteins for destruction in cellular ubiquitin-proteasome pathways. Different lentiviral Vifs have evolved to use the same canonical E3 ubiquitin ligase complexes, along with distinct noncanonical host cofactors for their activities. Unlike primate lentiviral Vif, which recruits CBFβ as the noncanonical cofactor, nonprimate lentiviral Vif proteins have developed different cofactor recruitment mechanisms. Maedi-visna virus (MVV) sequesters CypA as the noncanonical cofactor for the Vif-mediated ubiquitination of ovine APOBEC3s. Here, we report the cryo-electron microscopy structure of MVV Vif in complex with CypA and E3 ligase components. The structure, along with our biochemical and functional analysis, reveals both conserved and unique structural elements of MVV Vif and its common and distinct interaction modes with various cognate cellular proteins, providing a further understanding of the evolutionary relationship between lentiviral Vifs and the molecular mechanisms by which they capture different host cofactors for immune evasion activities.

Co-infection of maedi visna virus (MVV) with jaagsiekte sheep retrovirus (JSRV) and mycoplasma in Indian sheep and Goats

Co-infection of maedi visna virus (MVV) with jaagsiekte sheep retrovirus (JSRV) and mycoplasma in Indian sheep and Goats

Impact of Four Ovine TMEM154 Haplotypes on Ewes during Multiyear Lentivirus Exposure.

Polypeptide variation encoded by the ovine transmembrane protein 154 gene (TMEM154) is associated with susceptibility to ovine lentivirus, the causative agent of Ovine Progressive Pneumonia (OPP) and Visna/Maedi. Our aim was to compare the four most prevalent TMEM154 haplotypes on the incidence of infection and ewe productivity during natural multiyear virus exposure. Prospective cohort studies were designed to test gene action and estimate effects of TMEM154 haplotypes encoding distinctive variant residues: K35 (“1”), I70 (“2”), ancestral (“3”), and A4del/M44 (“4”). Exposure consisted of co-mingling infected ewes at a rate greater than 30% with serological status evaluated every four months. For ewes with one or two copies of the highly susceptible haplotypes “2” and ”3”, the infection prevalence steadily increased to nearly 100% at 55 months. Haplotypes “2” and “3” were equally susceptible and dominant to haplotype “1”. A difference was not detected (p < 0.53) in the magnitude of effect with haplotype combinations of “1” and ”4”. The ewe infection prevalence with “1,1”; “1,4”; and “4,4” was 10% to 40% at 55 months. The latter suggested that two copies of the K35 amino acid substitution (“1”) were as effective as a homozygous TMEM154 “knockout” with the frame-shift deletion mutation (“4”) in reducing infection susceptibility. When considering ewe reproductive performance, a difference was not detected when comparing haplotypes “2”, and “3” to each other, or “1” and “4” to each other. Our study indicated that ewes with two copies of the severely truncated versions of TMEM154 (“4,4”) had normal lamb productivity. Without complete understanding of the natural function of TMEM154 our recommendations to producers interested in using TMEM154 selection to reduce their flock’s genetic predisposition to OPP are encouraged to increase the frequency of TMEM154 haplotype K35 (“1”) since it encodes a full-length protein with minimal difference to the ancestral polypeptide.

Evaluation of three commercial ELISA tests for serological detection of maedi-visna virus using Bayesian latent class analysis

Early and accurate diagnosis is fundamental for successful surveillance and control of maedi-visna virus (MVV). MVV was detected in Norway in 2019, almost 14 years after the previous outbreak. Genetic analysis indicates persistence of the virus in the sheep population since 2005. The virus was not detected despite continuous serological surveillance. This emphasises the need for improved surveillance, which relies on an understanding of both diagnostic test performance, sampling strategy and the prevalence of the disease. This study therefore aims to evaluate three commercial ELISA tests for MVV antibodies. We conducted a retrospective study using 615 samples from six flocks diagnosed with MVV in 2019. We ran all samples with the following three tests: ID Screen® MVV/CAEV Indirect (IDvet, Grabels, France), IDEXX MVV/CAEV p28 Ab Verification Test (IDEXX Laboratories, Maine, USA) and Elitest MVV/CAEV (Hyphen Biomed, Neuville-sur-Oise, France), hereinafter referred to as ID Screen, IDEXXp28 and Elitest respectively. Without a perfect reference test, we used Bayesian latent class analysis, including conditional dependence between tests, to estimate diagnostic accuracy and true prevalence in the flocks. Using recommended cut-off values, we found that ID Screen and Elitest had significantly higher sensitivity (Se) estimates (99.3 % [97.4–100.0, 95 % Posterior Credible Interval] and 97.4 % [94.1–99.7 %], respectively) than IDEXXp28 (79.5 % [72.3–86.0 %]), while IDEXXp28 and ID Screen had significantly higher specificity (Sp) estimates than Elitest (99.7 % [99.1–100.0], 99.1 % [98.0–99.8 %] and 93.7 % [91.4–95.7 %], respectively). The estimated true prevalence in the six flocks ranged from a median of 0.8–93.5 %. Combining ID Screen and Elitest in serial interpretation showed the highest median Se and Sp (96.7 % [92.0–99.1] and 100.0 % [99.9–100.0], respectively), as well as the highest median positive predictive value (PPV) for the population with the lowest prevalence. Our study supports the use of ID Screen for screening. Further verification with Elitest in serial interpretation will enhance the PPV.

Ovine Johne's disease

Ovine Johne's disease (OJD) is commonly considered to be an ‘iceberg disease’ whereby the majority of infected individuals and the majority of the production losses associated with infection are subclinical, and only a small proportion of the infected animals develop overt, easily identifiable clinical signs. This small number of clinical cases represent the ‘tip’ of a much larger OJD subclinical iceberg, the economic impact of which is chronically underestimated. Several other diseases have also been described in this way, such as maedi visna, caseous lymphadenitis, ovine pulmonary adenomatosis and border disease. However, OJD is the most important of these diseases because of the high prevalence of flocks infected and economic impact of production losses that result from sub-clinical infections. This article reviews disease transmission, diagnosis, control and prevention as well as recent work providing estimates of the prevalence of OJD within the national flock.

Evolutionary Conservation of PP2A Antagonism and G2/M Cell Cycle Arrest in Maedi-Visna Virus Vif.

The canonical function of lentiviral Vif proteins is to counteract the mutagenic potential of APOBEC3 antiviral restriction factors. However, recent studies have discovered that Vif proteins from diverse HIV-1 and simian immunodeficiency virus (SIV) isolates degrade cellular B56 phosphoregulators to remodel the host phosphoproteome and induce G2/M cell cycle arrest. Here, we evaluate the conservation of this activity among non-primate lentiviral Vif proteins using fluorescence-based degradation assays and demonstrate that maedi-visna virus (MVV) Vif efficiently degrades all five B56 family members. Testing an extensive panel of single amino acid substitution mutants revealed that MVV Vif recognizes B56 proteins through a conserved network of electrostatic interactions. Furthermore, experiments using genetic and pharmacologic approaches demonstrate that degradation of B56 proteins requires the cellular cofactor cyclophilin A. Lastly, MVV Vif-mediated depletion of B56 proteins induces a potent G2/M cell cycle arrest phenotype. Therefore, remodeling of the cellular phosphoproteome and induction of G2/M cell cycle arrest are ancient and conserved functions of lentiviral Vif proteins, which suggests that they are advantageous for lentiviral pathogenesis.

Seroprevalence and risk factors associated with maedi visna virus in sheep population in southwestern Croatia

The objective of this cross-sectional study was to detect the presence of maedi visna virus (MVV) infections in sheep in three counties in southwestern Croatia: Istria County, Primorje-Gorski Kotar County and Lika-Senj County, and to estimate the influence of geographical location, breed, age and gender as risk factors on the prevalence rate. A total of 460 randomly selected sheep were tested using a commercially available ID Screen® MVV/CAEV Indirect screening test, VISNAS-5P (ID.VET, Grabels France) for detection of antibodies against the Maedi-Visna virus. The prevalence rate for the entire population was 10.00 % (95 % 7.26 - 12.74 %), The highest seroprevalence of MVV was found in Istria County (19.02%, CI 95% 13.35 –24.70%), followed by Lika-Senj County (5.43 %, CI 95 % 2.17- 8.70) and Primorje-Gorski Kotar County (1.07 %, CI 95 % -1.03 – 3.17) (P&lt;0.01). When comparing the seroprevalence among breeds, statistically significant differences were observed. The largest number of positive sheep was found in the following breeds: Istrian Pramenka (22.97%, CI 95% 13.39 - 32.55%), Jezersko-Solcava sheep (23.53%, CI 95% 11.89 - 35.17%%), Pramenka (13.16%, CI 95% 2.41 - 23.91%) and Lika sheep (9.78%, CI 95% 3.71- 15.85%). Prevalence rates in other examined breeds (Krk sheep, Pag sheep and Romanov sheep) were lower than 2 % (P&lt;0.01). No statistically significant differences in seroprevalence between sex and age were found. According to risk estimation, the main risk factors were found to be geographical location and breed. In Istria County, seroprevalence was 4.77 ( CI 95 % 2.67 – 8.54) higher than in other examined areas (OR = 5.66, CI 95 % 2.97-10.79) (P&lt;0.01). As for breeds, significant differences were observed between Jezersko-Solcava sheep and Lika sheep (OR = 2.84, CI 95% 1.13-7.14) and Istrian Pramenka in relation to Pag sheep (OR 22.51,, CI 95% 16.99-119.73), Krk sheep (OR 19.53, CI 95% 5.80-108.27), and Lika sheep (OR 2.35, CI 95% 1.17-6.47). This cross-section study indicates the circulation of MVV in this sheep population in Croatia, and represents the first research into the risk factors for MVV in sheep in southwestern Croatia.

The First Genomic Analysis of Visna/Maedi Virus Isolates in China.

Visna/Maedi virus (VMV) is a neglected pathogen that damages sheep and goats' nervous and respiratory systems. The virus was discovered 80 years ago and has been endemic in China for nearly four decades; nevertheless, there is little information regarding Chinese isolates' genotypes and genomic characteristics. In this study, the proviral DNA of strains isolated in 1985 and 1994 were extracted, and the proviral DNA was subjected to Illumina sequencing combined with Sanger sequencing of poor coverage regions. The results showed that the two isolates were clustered with genotype A2 and shared 78.3%−89.1% similarity to reference VMV genome sequences, with the highest similarity (88.7%−89.1%) to the USA strain USMARC-200212120-r (accession no. MT993908.1) and lowest similarity (78.3%−78.5%) to the Italian strain SRLV009 (accession no. MG554409.1). A maximum-likelihood tree showed that the Chinese VMV strains and the USA strain 1150 (accession no. MH916859.1) comprise a monophyletic group with a short tree branch. Our data filled the gap in genomic analysis and viral evolution in Chinese VMV strains, and would be benefit China's source-tracing and eradication program development in China.

Alternative Molecular Tools for the Fight against Infectious Diseases of Small Ruminants: Native Sicilian Sheep Breeds and Maedi-Visna Genetic Susceptibility

Simple SummaryLocal 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.

Antimicrobial Properties of Lauric Acid and Monolaurin in Virgin Coconut Oil: A Review

AbstractVirgin coconut oil is obtained by wet processing of coconut milk using fermentation, centrifugation, enzymatic extraction, and the microwave heating method. Presently, VCO has several positive effects and benefits to human health, hence, it is regularly consumed and widely known as a unique functional food. VCO contains lauric acid (45 to 52 %). By lipase in the digestive system, VCO can undergo a breakdown into lauric acid, 1‐monolaurin, and 2‐monolaurin. These components have both hydrophilic and lipophilic groups and are also recognized as excellent antimicrobial lipids. Furthermore, lauric acid and monolaurin can be used as antibacterial, antifungal, and antiviral with broad‐spectrum inhibition. Lauric acid and monolaurin have a strong ability to destroy gram‐positive bacteria, especially S. aureus, fungi such as C. Albicans, and viruses including vesicular stomatitis virus (VSV), herpes simplex virus (HSV), and visna virus (VV). Lauric acid and monolaurin interact with certain functional groups located in the cell membrane and can cause damage to the cell. In general, the potential of VCO as healthy food is contributed by lauric acid and monolaurin which are antimicrobial agents.

Pathological, molecular, and serological study of small ruminant lentiviruses in Jordan.

Background and Aim:Maedi-visna is a chronic viral disease of sheep with worldwide distribution causing substantial economic losses to the small ruminant industry. Pneumonia and mastitis are the main manifestations of the disease. This study aimed to investigate the occurrence of maedi-visna virus (MVV) in sheep using histopathology and nested polymerase chain reaction (PCR) techniques and also to estimate the seroprevalence of small ruminant lentiviruses (SRLVs) in sheep and goats using commercially available enzyme-linked immunosorbent assay (ELISA).Materials and Methods:Lung tissue samples from 380 sheep were collected and fixed in 10% formalin for histopathology and molecular diagnosis of MVV. Separately, 806 serum samples were randomly collected from 633 sheep and 173 goats to detect the seroprevalence of SRLVs using ELISA.Results:The results showed that 4.7% of lung samples (n=190) were positive by both histopathology and nested PCR, 5.8% (n = 380) were positive by histopathology only (have lymphoid follicular hyperplasia), and 7.4% (n = 190) were positive by nested PCR only. Statistical analysis revealed a moderate agreement between the two tests (Kappa=0.451, n = 190). Serology results revealed that sheep and/or goats herd prevalence was 59.8% (n = 87), while individual seroprevalence in sheep (40.1%, n = 633) was significantly higher than that in the other six countries and also significantly higher than that in goats (18.5%, n = 173) (at p < 0.05).Conclusion:The moderate statistical agreement between nested PCR and histopathological diagnosis of MVV in formalin-fixed paraffin-embedded sheep lung tissue samples (Kappa=0.451, n = 190) suggests combining both tests for more sensitive MVV detection in sheep lung samples. SRLVs seropositivity in sheep was significantly higher than in goats, thus, it is of high concern and urges the inquiry into the economic impact of the disease and the financial benefit of adopting eradication measures.

Multivalent interactions essential for lentiviral integrase function

A multimer of retroviral integrase (IN) synapses viral DNA ends within a stable intasome nucleoprotein complex for integration into a host cell genome. Reconstitution of the intasome from the maedi-visna virus (MVV), an ovine lentivirus, revealed a large assembly containing sixteen IN subunits1. Herein, we report cryo-EM structures of the lentiviral intasome prior to engagement of target DNA and following strand transfer, refined at 3.4 and 3.5 Å resolution, respectively. The structures elucidate details of the protein-protein and protein-DNA interfaces involved in lentiviral intasome formation. We show that the homomeric interfaces involved in IN hexadecamer formation and the α-helical configuration of the linker connecting the C-terminal and catalytic core domains are critical for MVV IN strand transfer activity in vitro and for virus infectivity. Single-molecule microscopy in conjunction with photobleaching reveals that the MVV intasome can bind a variable number, up to sixteen molecules, of the lentivirus-specific host factor LEDGF/p75. Concordantly, ablation of endogenous LEDGF/p75 results in gross redistribution of MVV integration sites in human and ovine cells. Our data confirm the importance of the expanded architecture observed in cryo-EM studies of lentiviral intasomes and suggest that this organization underlies multivalent interactions with chromatin for integration targeting to active genes.

An outbreak of visna-maedi in a flock of sheep in Southern Brazil.

Visna-maedi is a multisystemic and progressive inflammatory disease caused by a non-oncogenic retrovirus (Visna-maedi virus, VMV). An outbreak of visna-maedi occurred in Southern Brazil in sheep with clinical signs of blindness and stumbling gait. At post-mortem examination, all animals had similar lesions, including heavy non-collapsed lungs and multifocal yellow areas in the cerebral white matter, affecting mainly the periventricular region. These lesions corresponded histologically to lymphocytic interstitial pneumonia and histiocytic periventricular encephalitis surrounding areas of necrosis, in addition to significant demyelination in the brain. Serology was performed in all the sheep from the flock and 14% were seropositive for VMV. The presence of VMV was confirmed through PCR and partial sequencing of the 5'LTR. Sequencing demonstrated that the virus had 89.7 to 90.0% of nucleotide identity with VMV strains reported in the USA. This is the first description of clinical disease related to VMV in Brazil leading to economic losses. This study calls for the need to implement control measures to prevent the spread of small ruminant lentiviruses in Brazil.

Detection and immune cell response of natural maedi visna virus (MVV) infection in Indian sheep and goats

Maedi is a lentiviral disease characterized by progressive interstitial pneumonia with humoural as well as cell mediated immune response. The present investigation was designed to detect the presence of MVV in different biological samples and to evaluate the immune response in naturally MVV infected sheep and goats. Total of 701 biological samples (289 lung tissues, 233 blood, 54 brain tissues, 74 mammary gland tissues and 51 joint tissues were screened for the MVV by nested PCR. MVV nucleic acid was detected in 10.41% of samples and it was observed that sheep samples showed positivity of 8.7% and goat samples 12.6%. Blood samples showed highest positivity (14.59%) followed by joint tissue (13.72), lungs (8.6%), mammary gland (8.1%) and brain (1.85%). MVV p28 antigen was detected in the cytoplasm of mononuclear cells, particularly in the macrophages of lungs and lymph nodes. Antibodies against SRLVs were detected by cELISA and seroprevalence of 19.58% was observed in both sheep and goats serum samples. The seropositivity was higher in sheep (22.9%) as compared to the goats (15.59%). IHC was done to identify the nature of the immune cells infiltrated in the MVV infected tissues and it was observed that B cells, CD8+ and macrophages were the predominant immune cells infiltrated in the lungs showing MVV infection. Expression of the cytokines was assessed by real time PCR and it was observed that expression of IL-10, IFN-γ, TNFα, IL-4, IL-2 and IL6 was down regulated in most of the cases but few samples showed upregulation. In conclusion, MVV is circulating in the sheep and goat population of the India and the disease causes altered immune response in the animal which may make the infected animals more prone to other infectious diseases.

Clearance of Maedi-visna infection in a longitudinal study of naturally infected rams is associated with homozygosity for the TMEM154 resistance allele.

Maedi-visna (MV) is a lentiviral disease of sheep responsible for severe production losses in affected flocks. There are no vaccination or treatment options with control reliant on test and cull strategies. The most common diagnostic methods used at present are combination ELISAs for Gag and Env proteins with virus variability making PCR diagnostics still largely an experimental tool. To assess variability in viral loads and diagnostic tests results, serology, DNA and RNA viral loads were measured in the blood of 12 naturally infected rams repeatedly blood sampled over 16 months. Six animals tested negative in one or more tests at one or more time points and would have been missed on screening programmes reliant on one test method or a single time point. In addition the one animal homozygous for the ‘K’ allele of the TMEM154 E35K SNP maintained very low viral loads in all assays and apparently cleared infection to below detectable limits at the final time point it was sampled. This adds crucial data to the strong epidemiological evidence that this locus represents a genuine resistance marker for MV infection and is a strong candidate for selective breeding of sheep for resistance to disease.

First molecular detection of Maedi-Visna virus in Awassi sheep of Middle Iraq regions

Respiratory viral infections cause significant economic losses in sheep production. This preliminary molecular study aimed to detect the Maedi-Visna virus infection in Awassi sheep in three governorates in the middle region of Iraq. The presence of one or more of the specific four genes (gag, pol, env and LTR) were considered as positive result. A total of 210 blood samples of Awassi sheep were collected for the purpose of the project. The molecular prevalence of Maedi-Visna virus in sheep was 12.85% (27/210). As a result, Maedi-Visna virus was observed in sheep with chronic respiratory system disease with non-significant difference between governorates and between primers percentage (P&gt;0.05). Sequencing studies strongly suggested that Maedi-Visna virus originated in Iraq. This is the first study describing Iraqi Maedi-Visna virus sequences with molecular characterisation of gag, pol, env and LTR genes, suggesting that Maedi-Visna virus originated in Iraq.

Distribution of Maedi Visna Virus (MVV) in Different Organs of the Spontaneously Affected Small Ruminants

Distribution of Maedi Visna Virus (MVV) in Different Organs of the Spontaneously Affected Small Ruminants

Detection and Immune Cell Response of Natural Maedi Visna Virus (MVV) Infection in Indian Sheep and Goats

Detection and Immune Cell Response of Natural Maedi Visna Virus (MVV) Infection in Indian Sheep and Goats

Detection of Maedi-visna virus in sheep in Nineveh province

This is a primary study in detecting a specific antibody of the Maedi-visna virus (MVV) in blood samples and viral antigen in nasal swabs from sheep. Two hundred and forty nasal swabs and blood samples were collected from sheep of different ages and health statuses in Nineveh province, Iraq. Enzyme-linked immune sorbent assay was used to detect specific antibodies against MVV specific proteins gp135 and p25, Whereas Agar gel immune diffusion (AGID) was used to detect antigens from nasal swabs using specific antibodies against gp135 proteins of MVV. Serological results using ELISA showed the total prevalence of MMV 22.9% and the highest prevalence of infection in sheep less than one-year-old 36.5% when compared with older animals 8.4%. Animals that suffering from respiratory problems had a higher prevalence of infection 25.7% compared with healthy animals 6.9%. AGID showed an identical reaction between Maedi-visna viruses and specific rabbit antisera with a total infection rate of 12.9%. The highest prevalence of infection was 22.4% recorded in animals less than one-year-old, the lowest percentage of infection in animals more than two years of age was 1.4%. Animals suffering from respiratory signs also showed high prevalence of infection 13.8%, while the lowest percentage of infection were recorded in healthy animals 4.6%. It has been concluded that the high prevalence of infection rate in sheep less than one-year-old and the animals which suffered from respiratory problems had higher prevalence according to ELISA and AGID testes.