Chancroid vaccine promising in pigs

NEW YORK, May 13 (Reuters) A vaccine against the bug that causes the sexually transmitted disease known as chancroid has shown promise in experiments conducted in pigs, scientists report. Not only would such a vaccine prevent or reduce the painful open sores of chancroid on the genitals, it could also reduce the transmission of HIV, senior researcher Dr Christopher Elkins told Reuters Health.

Chancroid, a highly contagious STD, is very common in Africa and becoming more common in the United States. Chancroid can be effectively treated with antibiotics. Left untreated, chancroid may facilitate the transmission of HIV, the virus that causes AIDS.

Elkins, at the University of North Carolina in Chapel Hill, and his associates purified a key part of Haemophilus ducreyi, the bug that causes chancroid, and used it to vaccinate pigs on days 1, 21, and 42. Three weeks later, they inoculated the animals' skin with Haemophilus ducreyi. They report their results in the journal Infection and Immunity.

Even though characteristic chancroid lesions developed on the vaccinated pigs, the lesions 7 days later were smaller and less inflamed compared with lesions in pigs that were vaccinated with a placebo.

At the same time, lesions of the vaccinated pigs were sterile, whereas all 17 biopsies from sham-vaccinated pigs yielded viable Haemophilus ducreyi. Moreover, the blood of vaccinated pigs had high levels of antibodies against the chancroid bug.

Prevention of chancroid lesions may reduce transmission of HIV, because ''high concentrations'' of HIV-susceptible cells are present in chancroid ulcers, Elkins explained.

REUTERS SI ND1006