Comparative evaluation of immunofluorescent (IgM and IgG) and complement-fixing antibodies in influenza A infection.

The indirect immunofluorescent (FA) tests for detection of IgG and IgM antibodies to the internal antigens of influenza viruses were performed using single cell suspensions of baby hamster kidney cells. The IgG-FA test showed a good correlation with the complement fixation (CF) test performed with purified ribonucleoprotein (RNP) as antigen than the CF test with whole virus antigen. Sera which were positive only in the IgM-FA test did not react in the RNP-CF test. A rapid diagnosis of influenza was not possible alone by detection of RNP specific IgM as relatively low titers were obtained in the IgM-FA test.