Prevention of herpes genitalis by the 'Bulgarian' vaccine EHSV-2(v)(PRK): Preliminary clinical evidence

Aim. To examine the antigenic properties of the formalin-inactivated herpes simplex virus type 2 (HSV-2) virus-particle vaccine F.HSV-2(v)(PRK), which has been used therapeutically in Bulgaria for 30 years, and to make prelim inary assessment of its potential protective efficacy by a follow-up of vac cinated patients with herpes genitalis. Methods. Properties of the vaccine were examined by standard immunological laboratory tests. Fifty-five patients at risk of herpes genitalia received 2-4 vaccinations and were monitored during a 6-year follow-up. Results. The vaccine was antigenic in laboratory tests and absorbed neutral izing antibody from hyperimmune rabbit serum against herpes simplex virus t ype 1 (HSV-1). In vaccinated patients, there was an overall contraction rat e of herpes genitalis of 5.4%. There was no evidence of significant local o r generalized adverse effects from vaccination. Conclusion. Bulgarian vaccine F.HSV-2(v)(PRK) may have protective efficacy, which, in association with its apparent safety from our findings and from its clinical use for over 30 years in Bulgaria, suggests that it should be scrutinized by a formal clinical trial.