[Detection of polymeric IgA antibody to herpes simplex virus by pretreatment of sera with Streptococcus pyogenes--its application to diagnosis of primary infection].

In 17 patients of genital herpes virus infections, herpes simplex virus (HSV)-specific IgA antibody responses were analyzed using an enzyme-linked immunosorbent assay (ELISA) and the absorption of sera with Streptococcus pyogenes, AW43 and AR1, which bind monomeric IgA (m-IgA) and IgG antibodies, respectively. The ratio of polymeric IgA (p-IgA) to total IgA was calculated from the formula, the p-IgA index = IgA activity after absorption/IgA activity before absorption. In early-convalescent-phase sera from primary cases, the p-IgA indices were 0.5-0.9, whereas in recurrent or provoked cases, they were lower than 0.2. There results indicate that the p-IgA index may be useful for rapid and simple differentiation of primary from non-primary HSV infections.