Vaccine For The Treatment of Genital Herpes On The Horizon?

(18 Nov 2002)

Several pharmaceutical companies are actively researching vaccines to prevent genital herpes recurrences. The theory of using vaccines as therapy has been around for many years, but it's only now that we are beginning to see vaccines powerful enough to produce the desired effects.

Initial results with an experimental therapeutic vaccine, ICP10DPK, based on recombinant HSV-2 virus, from a Mexican 64-patient study were reported in October 2002. The study found that the vaccine reduced the number of genital herpes episodes by three fold versus the previous year in patients who previously experienced 5-24 outbreaks per year.

Participants in the trial had experienced a minimum of five documented genital herpes recurrences in the previous year. Patients were examined within 72 hours of lesion occurrence. If accepted into the study, the patient was vaccinated in a shoulder muscle at days 7, 17 and 28 after initiation of lesion occurrence. Patients were randomized for inoculation with vaccine or placebo. Herpes recurrences were recorded by patient diaries and physician examination. During the observation period, the researchers found that recurrences in the vaccine group were prevented in 37.5% of the patients, whereas in the placebo group, 100% of the patients had at least one recurrence. The mean number of illness days was ten for the vaccine group and 18 days for the placebo group.

However, a study conducted in Nova Scotia and reported at ICAAC in San Diego in September 2002, has suggested that the target for genital herpes vaccines should be HSV-1. HSV-1 is the most common type of herpes simplex virus, and usually causes facial herpes but face to genital cross-infection can occur.

The researchers analyzed 6,885 genital swabs taken from a wide cross-section patients from their laboratory database at the Queen Elizabeth II HSC, the only virology laboratory in the Nova Scotia province. They found that overall, HSV-1 was recovered more often that HSV-2. This trend was particularly striking in young women aged 30 years in whom 71.2% of positive swabs showed the presence of HSV-1 versus 45.5% for males. The researchers attributed this shift toward HSV-1 infections to declining rates of acquisition of HSV-1 in children via non-sexual routes ie: kissing, or to changing sexual practices.