But what if a vaccine against another sexually transmitted infection found widely in that region of Africa chancroid was relatively easy to develop and could reduce transmission of HIV as much as 10-fold?

That may be the case, according to researchers from the University of North Carolina at Chapel Hill's School of Medicine and N.C. State University's College of Veterinary Medicine.

Their study appears in the April issue of the journal Infection and Immunity. The lead author is Dr. Galyna Afonina, postdoctoral research associate in the UNC Center for Infectious Diseases. Senior author is Dr. Christopher Elkins, research associate professor in the departments of medicine and microbiology and immunology in UNC's School of Medicine.

Chancroid, a sexually transmitted disease that causes genital ulcers, is rare in the United States but takes hold in communities that have little or no access to health care, such as in Africa. Recent studies show that genital ulcer diseases such as chancroid can enhance HIV transmission three- to 10-fold.

"There is considerable evidence that genital ulcers are independent risk factors for the transmission of HIV, and chancroid may be the most important one," said Elkins.

Chancroid is caused by a bacterium, Haemophilus ducreyi, that normally infects only humans. Unlike most bacteria, Haemophilus species are unable to synthesize heme, the ferrous, or iron-containing, component of hemoglobin, and obtain it from host hemoglobin.

The researchers found that immunizing swine with a purified hemoglobin receptor protected the animals from a challenge infection, even after multiple attempts at infection.

Blood tests showed that the immunized pigs formed antibodies that prevented the chancroid bacteria from
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Contact: Leslie H. Lang
llang@med.unc.edu
919-843-9687
University of North Carolina School of Medicine
5-May-2006