Immunological reactions of the Coxsackie viruses. II. The complement fixation test.

The preparation of complement-fixing antigens for the Coxsackie group of viruses (C virus) is described. This includes the manufacture of crude antigens, their subsequent treatment with protamine sulfate to remove non-specific interfering substances, and their concentration by ultracentrifugation. The plate complement fixation technique of Fulton and Dumbell is described in detail as it has been used for the Coxsackie viruses. Seven strains of C virus have been cross-tested in the plate complement fixation test and have been found to belong to six immunologically distinct types. The temporal pattern of complement-fixing antibodies in human beings infected with two types, Ohio-1 and Easton-2, respectively, has been studied. In the former the antibodies rise to a peak rather late in convalescence (3rd month) and in the latter, complement-fixing antibodies are already present at high levels in the acute phase serum. The problems of serodiagnosis are briefly discussed.