Antibodies to the HFRS virus in the human population of European RSFSR as detected by radioimmunoassay.

Natural immunity to the causative agent of hemorrhagic fever with renal syndrome (HFRS) has first been studied using radioimmunoassay (RIA) in the human population of the Bashkir ASSR with the highest incidence of this infection and of five other regions of the RSFSR with lower incidence of HFRS. The antigen was prepared as a suspension of lungs of rodent from natural HFRS foci and contained a high concentration of virus protein. 12,000 sera from the population of 6 areas of the RSFSR were examined. In the Bashkir ASSR antibodies were detected in 13.7 per cent of the subjects examined, this figure varying in different districts from 4.0 to 41.5 per cent. In the other areas the portion of immune subjects varied from 6.7 per cent in Kuybyshev region to 1.6 per cent in Vladimir region. No correlation between the size of the immune portion of the population and average incidence rates for 5 years was observed. In Bashkiriya, immunity was found in 14.9 per cent of men and 11.8 per cent of women. In other regions, the per cent of women with antibodies to HFRS virus was also lower. In the age-group under 40 the percentage of immunity was lower (11.4 per cent) than in older age-groups (17.4 per cent). The portion of immune subjects varied in different occupation groups. In HFRS convalescents the antibody was found to persist in high titre for 20 years (the observation period).