Demonstration of Antigenic Relationship between Mumps Virus and Hemagglutinating Virus of Japan

In sera from 22 of 24 cases of clinical mumps infection in young adults a heat stable factor reactive with the Hemagglutinating Virus of Japan (HVJ) increased in titer during the course of the illness. This factor was not affected by RDE and was measurable by the hemagglutination inhibition, complement fixation, and neutralization techniques. A similar response was not detectable in rabbits or mice following injection of mumps virus. Sera from 60 individuals were tested for activity against both HVJ and mumps virus. Twenty-eight were found to inhibit HVJ and detectable antibody against mumps virus was found in 22 of these, suggesting that much of the antibody against HVJ found in sera of persons in the United States may be the result of mumps infection rather than actual infection with HVJ.