Early Detection of Maedi-Visna (Ovine Progressive Pneumonia) Virus Seroconversion in Field Sheep Samples

Abstract

The aim of this work was to investigate whether an enzyme-linked immunosorbent assay (ELISA) was useful for early detection of maedi-visna virus (MVV) infection in sheep under field conditions. An ELISA based on p25 recombinant protein and a gp46 synthetic peptide was used. Sequentially obtained serum samples (n = 1,941) were studied for 4 years. ELISA results were compared with those of the agar gel immunodiffusion (AGID) test, and results of both tests were compared with a reference result established using consensus scores for at least 2 of 3 serologic techniques (AGID, ELISA, and western blotting, which was used to resolve result discrepancies between the other 2 techniques). A total of 247 discrepancies were observed between ELISA and AGID. Of these, 131 were due to an earlier detection of 120 sera by the ELISA and 11 sera by AGID. The remaining discrepancies (116) were due to the presence of false reactions in both tests. Fewer false-negative results were found by ELISA than with AGID (6 vs. 69 sera, respectively), whereas the number of false-positive results was virtually the same for ELISA and AGID (21 vs. 20, respectively). In relation to the reference result, ELISA sensitivity and specificity were 97.8% and 98.2%, respectively, whereas values for AGID were 76.3% and 98.3%, respectively. The agreement between ELISA and the reference result was higher than that between AGID and the reference result (K value: 0.96 and 0.77, respectively). A variation in the ELISA signal (based on optical density) was observed during the study period, suggesting different antibody levels throughout the animal's life. The ELISA was useful for detecting MVV-infected sheep in field conditions and has potential for use in control and eradication programs.

Maedi-visna virus infection of ovine mammary epithelial cells

“…The association found in this study between clinical mastitis, seropositivity to MVV by ELISA and viral detection in the mammary gland was high, with one exception. Among the serologic tests used in this study to detect MVV antibodies, the increased sensitivity observed in the ELISA with respect to AGID was expected according to previous studies [38,44] and confirmed by the presence of viral genome and proteins in histopathological observations.…”

“…A seronegative accredited Latxa breed flock was used for supply of control animals. The serological test for classification of flocks and animals was based on a recombinant ELISA test (Elitest ® , Hyphen BioMed, Neuville/Oise, France, formally known as Innotest ® , Innogenetics, Ghent, Belgium) [38,44]. A standard agar gel immunodiffusion test (AGID) for MVV (CVL, Weybridge, United Kingdom) was also applied [46].…”

Padronização do Elisa indireto e Western Blot para diagnóstico da artrite-encefalite caprina

“…Possui fácil aplicabilidade e alta especificidade (Varea et al, 2001). Como desvantagem, o teste somente detecta altos níveis de imunoglobulinas, o que permite a ocorrência de falso-negativos no rebanho (McConnell et al, 1998).…”

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

“…However, the diagnostic techniques should be chosen according to the cost-benefit ratio, commercial availability, and access to diagnostic laboratories (GOUVEIA, 2012). When only AGID diagnosis is available, given its high specificity (Table 1), monitoring by AGID in the early stages of SRLV control programs can be used alone (VAREA et al, 2001;PINHEIRO et al, 2006a;GOUVEIA, 2012). This strategy allows falsenegative goats to remain in the herd for a longer time, thus contributing to virus transmission.…”

“…Other serological techniques such as WB and dot blot (DB) have more limited use due to cost, speed, convenience, or availability. The World Organization for Animal Health (OIE) recommends the use of AGID or ELISA for diagnosis of SRLV infection (VAREA et al, 2001;OIE, 2008;REINA et al, 2009). …”