U.S. scientists have identified a potential target for a vaccine to fight Chlamydia -- the world's most prevalent sexually transmitted bacterial infection.

Researchers at the University of Pittsburgh Medical Center's Children's Hospital, led by Dr. Toni Darville, identified a plasmid-deficient strain of Chlamydia trachomatis that, when investigated in an animal model of genital tract infection, failed to cause disease. Plasmids are small molecules of DNA.

"This finding represents a major step forward in our work to eventually develop a vaccine against chlamydial disease," said Darville, a professor of pediatrics and microbiology/immunology. "If we can identify plasmid-deficient derivatives of the C. trachomatis strains that infect humans, they would have the potential to serve as a vaccine against this disease."

The study is reported in the Journal of Immunology.

Copyright 2007 by United Press International