Antigenic variation of the viruses belonging to the tick-borne encephalitis complex as revealed by human convalescent serum and monoclonal antibodies.

Solid-phase enzyme-linked immunoassay (ELISA) was used for the detection of antigenic relationships and/or differences among the viruses belonging to the tick-borne encephalitis (TBE) complex. Monoclonal antibodies of IgM class with haemagglutination-inhibiting activity to the Skalica strain of TBE virus were used to compare the TBE complex viruses. Antigenic analysis of 9 viruses of the TBE complex, isolated from Eurasia and America showed close relationships among them. Nevertheless, it was possible to differentiate the Skalica strain from Langat, louping-ill and Omsk haemorrhagic fever (OHF) viruses by ELISA when monoclonal antibodies and antigens were diluted 1:10,000. Monoclonal antibodies to the Russian spring-summer encephalitis virus did not react with the Skalica strain in immunofluorescence test. By the use of convalescent serum no reaction was found with louping-ill, Russian spring-summer encephalitis, Powassan and OHF viruses in haemagglutination-inhibition (HI) test.