Abstract
Equine Infectious Anemia Virus (EIAV) is a lentivirus in the family retroviruses, responsible for causing Equine Infectious Anemia (EIA). EIA is a worldwide concern as it is a threat to the horse industry and also affects international animal trade. It is therefore crucial for animals to be tested regularly to ensure they are free from the disease. The interaction of EIAV proteins with the host immune system during the course of a persistent infection have indicated that antibody responses are directed against the major core protein p26 and glycoproteins gp45 and gp90. Of these three proteins, p26 is the most conserved among antigenically variant viral isolates. Different formats of ELISAs based on these proteins have been used for serological diagnosis of EIAV infections with varying sensitivities. This study used antigenic epitopes of the two glycoproteins, gp90 and gp45, and the major core protein p26 as antigens, in different combinations (gp45p26, p26gp90, gp90gp45 and gp45p26gp90) expressed as fusion proteins to measure antibodies against EIAV in sera. Sera used were either from animals infected with EIAVwy and EIAVIRE, two of the four strains of the virus known till date or uninfected animals. A total of 86 samples were used for the analysis, 47 EIAV antibody positive serum samples (animals infected with EIAVwy and EIAVIRE strains) and 39 antibody negative serum samples. The same samples were analysed using a commercial ELISA kit. To account for plate-to-plate variation, ELISA results were calculated as arbitrary ELISA Units (EU). The results obtained with each of the fusion proteins were compared with the commercial ELISA and the results from both analyses were highly correlated. The Spearman correlation coefficients (Rho) were ≥0.74, (P < 0.01) for all comparisons, thus providing a measure of how closely two sets of results agree with each other. Thus, the different combinations of the gp90, gp45 and p26 proteins reported in this study show potential to be used for measuring EIAV antibodies in ELISA in animal serum.
M.Tech. (Biotechnology)