Abstract
An attempt was made to develop a complement fixation (CF) test for equine viral arteritis (EVA) which can be safely used in the countries free from EVA. The antigen was inactivated by 0.1% formalin, 50% ether, ultraviolet (UV) irradiation and heat at 70°C respectively. It was efficiently affected in viral infectivities by ether and formalin, but not at all in CF titers by formalin and UV irradiation. Ether degraded CF titers readily and UV irradiation caused random inactivation of virus. Heat showed incomplete effect on viral infectivities and declined CF titers. Therefore, the antigen inactivated by formalin was selected in the subsequent CF studies.
To evaluate the CF test using the inactivated viral antigen, it was conducted with 6 sero-positive horse sera against EAV in serum neutralization (SN) test. Three sera possessing SN titers of 1:128 to 1:256 revealed titers of 1:4 to 1:8 in CF test. The rest which had SN titers of less than 1:64 were negative.
