Genome differences among varicella-zoster virus isolates

The DNAs of 17 isolates of varicella-zoster virus (VZV) were analysed by restriction endonuclease cleavage and agarose gel electrophoresis. By comparing gel patterns of DNAs cleaved with only a few enzymes, all epidemiologically distinct isolates were shown to be unique. Two isolates recovered from members of a family infected in a common-source outbreak were identical to each other (4/4 enzymes) but distinct from the other strains. In addition, three isolates recovered at different times during the course of a single episode of zoster in another individual were identical by endonuclease analysis (4/4 enzymes) but once again were distinct from all other isolates. The differences that have been recognized in cleavage profiles of all VZV strains reported thus far map into four regions of the viral genome. Two of these variable regions lie within the long unique sequences while the other differences appear to map in each of the inverted repeat sequences.