Potential vaccine target for chlamydia

Scientists at Children's Hospital of Pittsburgh of UPMC have identified a potential target for the development of a vaccine against Chlamydia trachomatis, the most prevalent sexually transmitted bacterial infection in the world.

The researchers, led by Toni Darville, MD, chief of the Division of Pediatric Infectious Diseases at Children's, identified a plasmid-deficient strain of Chlamydia that, when investigated in an animal model of genital tract infection, failed to cause disease. Plasmids are small molecules of DNA.

Results of their study are published in the Sept. 15 issue of the Journal of Immunology.

“This finding represents a major step forward in our work to eventually develop a vaccine against chlamydial disease,” said Dr. Darville, senior author of the study and also a professor of pediatrics and microbiology/immunology at the University of Pittsburgh School of Medicine. “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.”

Dr. Darville is considered one of the world's foremost researchers of Chlamydia trachomatis, a bacterium which is the most frequently reported cause of sexually transmitted disease in the United States. Because symptoms are usually mild or absent, it can damage a woman's reproductive organs and cause irreversible damage, including infertility, before a woman ever recognizes a problem.

In this study, a plasmid-deficient strain derived from Chlamydia muridarum was introduced to mice. The mice became infected but did not develop the trademark signs of chlamydial disease, particularly damage to the oviduct, the tube that carries eggs from the ovaries, according to Catherine M. O'Connell, PhD, a researcher in Dr. Darville's laboratory and first author of the study.

“Not only did the mice not develop oviduct scarring after infection with the plasmid-deficient strain, we also found that the mice previously infected with these strains were protected against oviduct disease when later infected with fully virulent C. muridarum,” Dr. O'Connell said.