ENZYME-LINKED-IMMUNOSORBENT-ASSAY OF ANTIBODIES TO RABBIT HEMORRHAGIC-DISEASE VIRUS AND DETERMINATION OF ITS MAJOR STRUCTURAL PROTEINS

An ELISA was developed for the determination of antibodies to rabbit haemorrhagic disease virus (RHDV) in whole blood and blood serum of rabbits. Naturally acquired antibodies were detected in 19.4% of blood samples collected from 1461 rabbits in 43 farms apparently free of the disease, 19.7% samples were doubtful and 60.9% of the rabbits were free of antibodies to RHDV. Their presence has a considerable effect on the resistance of rabbits to infection with RHDV. Antibodies were also found in rabbit blood serum samples collected up to 12 years before the first outbreaks of RHD were reported. Up to 14 viral protein antigens were determined by PAGE and Western blot analysis, of which three with M(r) values of 61K, 38K and 52K were major proteins, the 61K being dominant. Our hyperimmune sera, a Chinese reference serum and sera with positive antibody titres, including those collected several years before the first outbreaks of RHD, reacted identically with these antigens in the Western blot analysis. The data obtained suggest that naturally acquired antibodies are a product of a specific response to prior infection with an avirulent strain of the virus.