EXPERIENCE OF USING SEROLOGICAL AND MOLECULAR TESTS TO DETECT EQUINE INFECTIOUS ANEMIA VIRUS IN HORSE

Abstract

Equine infectious anemia in horses is caused by equine infectious anemia virus (EIAV, Lentivirus, Retroviridae), affecting hematopoietic organs. The symptoms of the disease are relapsing or continued fever, anemia and a disturbance of cardiovascular functions. Duly virus detection is the only effective way to control infection. Serological methods used to indicate EIAV have some limitations. For instance, they did not allow identifying infected animals prior to seroconversion. Also an immunodeficiency can really occur when the content of virus specific antibodies is too low to be indicated. Here we report the results of comparative study of different serological and molecular techniques for diagnosis of equine infectious anemia in experimentally inoculated susceptible 9 month old foal. In the experiment, we used the kits for agar gel immunodiffusion assay (Russia) and ELISA (France) as serological tests, and our own developed test-systems for viral RNA detection by nested reverse transcription polymerase chain reaction (RT-PCR) with electrophoretic control and by realtime RT-PCR. Developed PCR-tests is based on amplification of EIAV gag-gene fragment using specific oligonucleotide primers. In blood, the viral RNA was detected by both test-systems from day 2 after animal inoculation until the end of observation at day 35. Specific antibodies were detected in diffuse precipitation reaction from day 30 and in ELISA from day 21 after animal inoculation. Thus, PCR-analysis could be used as an express-test for detecting EIAV genome prior to seroconvertion, and then other diagnostic methods should be further applied to verify the RCR data. The developed Russian test-systems and investigation techniques confirm the benefits of the PCR diagnosis in the early stages of the EIA.