Studies on the mechanism of antibody-mediated enhancement of Getah virus infectivity.

Inoculation on BHK-21 cells with Getah virus sensitized with hyperimmune homologous mouse antiserum resulted in higher infective titers than those obtained with non-sensitized control virus. This phenomenon was not observed with Vero cells. Experiments were carried out on the mechanism of this enhancement with the following results. When BHK-21 cells were pretreated with a mixture of UV-irradiated virus and antiserum before inoculation, the enhancement of infectivity of Getah virus was markedly decreased. IgG antibody against Getah virus which had been digested with 1--2% of pepsin did not show any enhancing activity. Sensitized sheep erythrocytes adhered to monolayered cultures of BHK-21 cells. These results indicate that the appearance of enhancing activity of a complex of the virus and antibody is closely related with the existence of a receptor for the Fc part of IgG on ordinary tissue culture cells, BHK-21 cells.