Persistent herpes simplex virus infection and mechanisms of virus drug resistance

Herpes simplex virus (HSV) is susceptible to a variety of antiviral compounds, most of which are nucleoside analogues that interfere with DNA metabolism involving the virus enzymes DNA-polymerase and thymidine kinase. Single mutations in the virus genome give rise to resistant mutants following selection in vitro in the presence of a particular drug, and in this respect HSV is similar to several other viruses. Such mutants have been invaluable research tools. HSV is responsible for a variety of lesions which tend to be recurrent, owing to the special ability of the virus to remain latent in and reactivate from neural tissue. The consequences of this upon clinical resistance are discussed in the present review. In fact, clinical resistance in HSV infections has not yet become widespread but does appear to be especially important in immunocompromised patients, including those suffering from AIDS. HSV is proposed as an important model for the investigation of drug resistance in other, more complex organisms, and with respect to antiviral strategies against the human immunodeficiency virus.