Difference in antibody reactivity between complement fixation and immune adherence hemagglutination tests with virus antigens.

Complement-fixing (CF) immunoglobulin M antibody to infantile gastroenteritis virus (a rotavirus) did not show the reactivity of immune adherence hemagglutination (IAHA). Early immunoglobulin G CF antibody produced both in patients and in guinea pigs experimentally infected with Japanese encephalitis virus (a flavivirus) had weak reactivity in IAHA test. However, late antibody showed higher titers by IAHA than by CF. These results suggested that early antibodies with lower affinity are inefficient in the IAHA reaction. The implications of this study are: (i) a low ratio of IAHA/CF antibody titers in a serum suggests a recent rotavirus infection; (ii) the IAHA reaction is more type specific than the CF reaction for identifying the serotype of antigenically cross-reacting viruses with hyperimmune sera.