Antigenic relationship between influenza C viruses.

The object of this study was to determine whether antigenic groupings exist among influenza C viruses. Altogether seven influenza type C strains were examined by reciprocal haemagglutination-inhibition and serum neutralization tests with sera produced in ferrets. Some biological properties were also compared and differences were found in their ability to agglutinate erythrocytes from various species, in their ability to adsorb onto rat and fowl erythrocytes, and in their rates of elution from the cells. The results obtained using these techniques confirmed that antigenic variation exists among influenza C viruses although it is not as clear cut as among influenza A viruses. This was supported by the results of a serological survey of antibody in different age groups.