Isolation and characterization of acyclovir-resistant strains of herpes simplex virus

A number of clinical studies have documented herpes simplex infections which appear to be resistant to nucleoside analogs; these include idoxuridine [1,2] and acyclovir [3]. Few, if any of the viruses isolated from such patients have yet been thoroughly characterized. We have isolated a number of acyclovir-resistant mutants by selection for resistance in tissue culture. The study of the biochemical and biological properties of these mutants has given some insight into the likely nature of resistant clinical strains. We have devised a number of simple tests to allow classification of laboratory mutants. We also draw attention to some of the difficulties the clinical virologist may encounter when analyzing putative resistant virus isolated from treated patients.