Antigenic relationship between hantaviruses analysed by immunoprecipitation.

Antigenic relationships between seven hantaviruses isolated in Sweden, Belgium, Korea, European U.S.S.R. and Asian U.S.S.R. were studied by radioimmunoprecipitation assays (RIPA) and indirect immunofluorescence tests (IFT). Animal immune sera and haemorrhagic fever with renal syndrome (HFRS) patient sera from the above countries were used. The strains fell into three antigenic groups by both RIPA and IFT: nephropathia epidemica (NE)-type, Korean haemorrhagic fever (KHF)-type and urban rat-type. This antigenic grouping conforms to the clinical grouping of the respective HFRS patients. The major cross-reactive antigen between the antigenic groups was the nucleocapsid protein. Of the two viral glycoproteins, the G2 exhibited weak cross-reactivity between the groups, while the G1 protein appeared to be the least cross-reactive. Patient sera collected at different intervals after the onset of disease showed a marked difference in their capacity to immunoprecipitate the homologous viral glycoproteins, although by IFT all sera had high titres. Host species-related antibody response differences were found by both RIPA and IFT. Using patient sera, a one-way cross-reactivity was seen between the NE-type and the KHF-type viruses. However, animal immune sera clearly demonstrated a reciprocal cross-reactivity between the two virus groups.