Evaluation of a Caprine Arthritis-Encephalitis Virus/Maedi-Visna Virus Indirect Enzyme-Linked Immunosorbent Assay in the Serological Diagnosis of Ovine Progressive Pneumonia Virus in U.S. Sheep
Abstract:A caprine arthritis-encephalitis virus (CAEV)/maedi-visna virus (MVV) indirect enzyme-linked immunosorbent assay (iELISA) was validated with samples from U.S. sheep and by the use of radioimmunoprecipitation as the standard for comparison. The sensitivity and the specificity were 86.0% (؎5.8%) and 95.9% (؎2.9%), respectively. The iELISA format and phylogenetic differences based on the MVV gag sequence contribute to the reduced sensitivity.The diagnosis of small ruminant lentivirus (SRLV) infections in sheep an… Show more
“…The tree was bootstrapped with 1000 pseudoalignments. Sequence representatives of SRLV subgroups 1 and 2 were included in the analyses, as were those of what we describe as subgroup 3, which infected a flock of sheep in the Western United States [29], and has not been tested for an association with TMEM154 genotypes.Figure 1
Neighbor-Joining network of SRLV partial
gag
sequences. The sequences were either produced in this study or were available from GenBank, and with amplification primer sites excluded correspond to nucleotide positions 1290–1771 of reference sequence [GenBank:NC_001452].…”
Section: Introduction Methods and Resultsmentioning
Small ruminant lentivirus (SRLV) infections of sheep are influenced by genetics on both the host and pathogen sides. Genetic variation in the ovine transmembrane 154 (TMEM154) gene associates with infection susceptibility, and distinct SRLV genetic subgroups infect sheep in association with their TMEM154 diplotypes. In this study, a novel SRLV subgroup was identified that naturally infected sheep with various TMEM154 diplotypes, including those homozygous for a rare frameshift mutation (A4 delta53), which is predicted to abolish TMEM154 protein function. Thus, these SRLVs may infect sheep that lack functional TMEM154, and may not be restricted by TMEM154 diplotypes in establishing infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-015-0162-7) contains supplementary material, which is available to authorized users.
“…The tree was bootstrapped with 1000 pseudoalignments. Sequence representatives of SRLV subgroups 1 and 2 were included in the analyses, as were those of what we describe as subgroup 3, which infected a flock of sheep in the Western United States [29], and has not been tested for an association with TMEM154 genotypes.Figure 1
Neighbor-Joining network of SRLV partial
gag
sequences. The sequences were either produced in this study or were available from GenBank, and with amplification primer sites excluded correspond to nucleotide positions 1290–1771 of reference sequence [GenBank:NC_001452].…”
Section: Introduction Methods and Resultsmentioning
Small ruminant lentivirus (SRLV) infections of sheep are influenced by genetics on both the host and pathogen sides. Genetic variation in the ovine transmembrane 154 (TMEM154) gene associates with infection susceptibility, and distinct SRLV genetic subgroups infect sheep in association with their TMEM154 diplotypes. In this study, a novel SRLV subgroup was identified that naturally infected sheep with various TMEM154 diplotypes, including those homozygous for a rare frameshift mutation (A4 delta53), which is predicted to abolish TMEM154 protein function. Thus, these SRLVs may infect sheep that lack functional TMEM154, and may not be restricted by TMEM154 diplotypes in establishing infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-015-0162-7) contains supplementary material, which is available to authorized users.
“…Competitive ELISA methods (cELISA CAEV of VMRD Inc. Pullman, WA) [184,185] using monoclonal antibodies to viral envelope protein (ENV-SU, gp135) epitopes have been developed [186] and indirect ELISAs have been frequently applied [187,188], although few of them have been compared internationally for both sheep and goats [189,190,191]. Currently available indirect standard ELISAs are used in different formats and designs.…”
Small ruminant lentiviruses (SRLV) cause a multisystemic chronic disease affecting animal production and welfare. SRLV infections are spread across the world with the exception of Iceland. Success in controlling SRLV spread depends largely on the use of appropriate diagnostic tools, but the existence of a high genetic/antigenic variability among these viruses, the fluctuant levels of antibody against them and the low viral loads found in infected individuals hamper the diagnostic efficacy. SRLV have a marked in vivo tropism towards the monocyte/macrophage lineage and attempts have been made to identify the genome regions involved in tropism, with two main candidates, the LTR and env gene, since LTR contains primer binding sites for viral replication and the env-encoded protein (SU ENV), which mediates the binding of the virus to the host’s cell and has hypervariable regions to escape the humoral immune response. Once inside the host cell, innate immunity may interfere with SRLV replication, but the virus develops counteraction mechanisms to escape, multiply and survive, creating a quasi-species and undergoing compartmentalization events. So far, the mechanisms of organ tropism involved in the development of different disease forms (neurological, arthritic, pulmonary and mammary) are unknown, but different alternatives are proposed. This is an overview of the current state of knowledge on SRLV genetic variability and its implications in tropism as well as in the development of alternative diagnostic assays.
“…Consequently, SRLVs are classified as a major infectious disease of small ruminants by the (Organisation Internationale des epizooties) OIE. In spite of OIE’s efforts and many eradication programs operating in various countries, SRLV still remains a challenge for farmers and health authorities due to the absence of an efficient vaccine or a diagnostic tool capable of detecting all SRLV subtypes [50,66]. …”
Section: Implications Of Srlv Genetic Diversity and Cross-species mentioning
Zoonotic events of simian immunodeficiency virus (SIV) from non-human primates to humans have generated the acquired immunodeficiency syndrome (AIDS), one of the most devastating infectious disease of the last century with more than 30 million people dead and about 40.3 million people currently infected worldwide. Human immunodeficiency virus (HIV-1 and HIV-2), the two major viruses that cause AIDS in humans are retroviruses of the lentivirus genus. The genus includes arthritis-encephalitis virus (CAEV) and Maedi-Visna virus (MVV), and a heterogeneous group of viruses known as small ruminant lentiviruses (SRLVs), affecting goat and sheep. Lentivirus genome integrates into the host DNA, causing persistent infection associated with a remarkable diversity during viral replication. Direct evidence of mixed infections with these two closely related SRLVs was found in both sheep and goats. The evidence of a genetic continuum with caprine and ovine field isolates demonstrates the absence of an efficient species barrier preventing cross-species transmission. In dual-infected animals, persistent infections with both CAEV and MVV have been described, and viral chimeras have been detected. This not only complicates animal trade between countries but favors the risk that highly pathogenic variants may emerge as has already been observed in the past in Iceland and, more recently, in outbreaks with virulent strains in Spain. SRLVs affecting wildlife have already been identified, demonstrating the existence of emergent viruses adapted to new hosts. Viruses adapted to wildlife ruminants may acquire novel biopathological properties which may endanger not only the new host species but also domestic ruminants and humans. SRLVs infecting sheep and goats follow a genomic evolution similar to that observed in HIV or in other lentiviruses. Lentivirus genetic diversity and host factors leading to the establishment of naturally occurring virulent versus avirulent infections, in addition to the emergence of new strains, challenge every aspect of SRLV control measures for providing efficient tools to prevent the transmission of diseases between wild ungulates and livestock.
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