The relative infrequency and low levels of neutralising and immunoprecipitating antibody to herpes simplex viruses types 1 and 2 in patients with a history of recurrent herpes genitalis.

Twenty-seven per cent of 70 patients with a history of recurrent herpes genitalis but no concomitant history of recurrent oral or peri-genital disease, had no detectable neutralising antibody against type 1 or type 2 herpes simplex virus; the prevalence and levels of neutralising antibody were similar to 53 patients with no history of herpetic disease and significantly lower than 67 patients with a history of recurrent herpes genitalis in association with oral or peri-genital disease all of whom had neutralising antibody against both virus types. There were similar differences between groups for immunoprecipitating antibody where 80% of patients were herpes genitalis alone had no detectable immunoprecipitating antibody. The results indicate that the failure to detect immunising and immunoprecipitating antibody in an individual's serum is compatible with a long and even severe history of recurrent herpes genitalis and consequently that the development of neutralising antibody does not necessarily indicate an episode of primary herpetic disease.