DIFFERENTIATION OF PRIMARY FROM NONPRIMARY GENITAL HERPES INFECTIONS BY A HERPES-SIMPLEX VIRUS-SPECIFIC IMMUNOGLOBULIN-G AVIDITY ASSAY

An immunoglobulin G (IgG) antibody avidity assay which uses protein-de naturing agents and a modification of an enzyme-linked immunosorbent a ssay have been investigated for their usefulness in distinguishing pri mary genital herpes simplex virus (HSV) infections from nonprimary inf ections, Forty-nine serum specimens from patients with primary, recurr ent, and nonprimary first-episode genital herpes were studied, The cle arest separation was obtained with 6 M urea treatment, giving mean avi dity indices of 0.395 far sera less than or equal to 100 days after th e infection and 0.879 for sera >100 days after the infection (P < 0.00 1). No significant difference in avidity indices was observed between the recurrent and nonprimary first-episode infections. Determination o f the avidity of HSV-specific IgG will improve the diagnostic potentia l of HSV serology.