Serologic and genotypic analysis of a series of herpes simplex virus type 1 isolates from two patients with genital herpes

Herpes simplex virus type 1 (HSV‐1) has been reported increasingly as a cause of genital herpes, although HSV‐1 is usually associated with oro‐labial herpes. In the present study, serum specimens and materials for viral isolation were obtained serially from two patients with recrudescent HSV‐1 genital infections to study serology and molecular epidemiology. Recurrent episodes, during which HSV‐1 was isolated, were followed by an increase in the level of anti‐HSV‐1 antibody, suggesting a booster effect from re‐exposure to viral antigens and the possible usefulness of the variation in the level of anti‐HSV‐1 antibody to diagnose recurrence. While genotypes of HSV‐1 isolates obtained from one patient were different from those from the other patient, genotypes of sequential HSV‐1 isolates obtained from the same patient were the same, implying that the recrudescent genital lesions of the two patients could be attributed to endogenous recurrence of a latent virus. Sera from one patient neutralized HSV‐1 isolates obtained from the other patient as well as HSV‐1 isolates obtained from the same patient. An HSV‐1 isolate obtained during a later episode in one patient was neutralized by sera taken before/during the later episode of the same patient, as effectively as an HSV‐1 isolate obtained during an earlier episode in the same patient; thus, in these two cases, HSV‐1 was assumed to have multiplied during recurrence despite the presence of an anti‐HSV‐1 antibody that could neutralize experimentally HSV‐1. J. Med. Virol. 81:1605–1612, 2009. © 2009 Wiley‐Liss, Inc.