Strain characteristics and features of ocular infection of herpes simplex virus type 1 isolates.

Herpes simplex virus type 1 isolates from 63 patients with herpetic keratoconjunctivitis were investigated. For the purpose of detecting strain differences neurovirulence was determined in mice, and viral DNA's were analyzed by digestion with EcoRI and Hind III restriction endonucleases. Neurovirulence differed by a factor up to 10(5) between individual strains and proved to be independent of the ratio between infectious and noninfectious particles in the stocks used. The endonuclease cleavage patterns revealed differences of the viral DNA structure which permitted us to distinguish seven clusters of strains. Correlations between neurovirulence and DNA markers could not be established nor could correlations be found between these markers and features of disease. The main reason for not finding a relationship in the latter case may be attributed to the significant role of host factors in the course of herpetic diseases.