Antigens of Bacteriophage øX174

Anti-oX serum contains precipitating antibodies specific for three antigenic sites in the virus. One of these sites is not accessible in whole virus, but is exposed in heated virusand in the related 70 S particle. Inactivating antibody, which blocks viral adsorption, is produced by immunization with intact virus, heated virusand the 70 S component. Inactivation by antibody is a first order process. The combination of antigen with antibody is partially reversible.