Characterization of herpes simplex virus strains isolated from patients with various diseases.

Herpes simplex virus strains (HSV) were isolated from various herpetic diseases. These HSV-strains isolated in Bulgaria (687) and in other countries (13) were studied by the neutralization test using standard type specific rabbit antisera and human gamma globulin. The serotype distribution of all strains showed: HSV-1 = 323 strains, HSV-2 = 372 strains, 5 strains behaved antigenically intermediate. A close correlation between the serotype of the strains and the localization of the lesions was established. All but four strains (1.24 per cent) isolated from the head belong to HSV-1, and only six HSV-strains (1.9 per cent) from lesions with other localizations were not HSV-2. Within six months to 8 years 2 to 4 herpes strains were isolated repeatedly from 30 patients. In 23 of these cases they were identical and in the other they showed different biological (3) or antigenical (4) properties. The results suggest, that under natural conditions some HSV-intermediate strains may exist.