Typing of Herpes Simplex Virus Strains of Genital and Nongenital Origins

Herpes simplex virus strains isolated from genital and nongenital sites were classified into type 1 (HSV‐1) and type 2 (HSV‐2) by endpoint neutralization tests using IgM of rabbits hyperimmunized with either HF (HSV‐1) or UW‐268 (HSV‐2) strain. It was found that about one‐third of the genital isolates belonged to type 1, in contrast to the general concept that HSV‐2 represents genital herpes strains. These HSV‐1 strains, differing from HSV‐2, were mostly isolates from acute herpetic lesions of female patients with constitutional symptoms. On the other hand, all nongenital isolates except one were determined to be HSV‐1. There was no intermediate type equally neutralizable by both types of IgM. A majority of the HSV‐2 strains produced large plaques in chick embryo (CE) cells before passage through avian cells. In contrast, all HSV‐1 strains failed to produce such large CE plaques even after serial passages through avian hosts.