Scientists at UCLA and NYU have deciphered the genome of the parasite causing trichomoniasis, and their research may lead to new approaches to improve the diagnosis and treatment of this common sexually transmitted disease. Trichomoniasis affects an estimated 170 million people a year, with more than five million cases reported in North America.
Led by Patricia Johnson, a UCLA professor of microbiology in the department of microbiology, immunology and molecular genetics, and Jane Carlton, an associate professor in the department of medical parasitology at New York University School of Medicine, the team of scientists took four years to crack the surprisingly large genome of this parasite. They published the draft sequence of the parasite’s genome in the Jan. 12 issue of the journal Science.
“Patricia Johnson cloned the first Trichomonas vaginalis gene in 1990 as an assistant professor at UCLA, and it is tremendously gratifying that she is now senior author on a landmark publication describing the entire genome,” said Jeffery F. Miller, chair of microbiology, immunology and molecular genetics at UCLA and UCLA’s M. Philip Davis Professor of Microbiology and Immunology. “The implications of this work range from fundamental insights into early evolution to understanding pathogenesis and developing drugs and vaccines. This is a major accomplishment in the field.”
“T. vaginalis is an extremely successful parasite, capable of establishing and maintaining infections in both men and women,” Johnson said. “Symptoms vary greatly among infected individuals, and the reason for this wide range of variable pathogenic outcomes is poorly understood. Among the many new insights brought by deciphering the genome sequence of this organism are ones that provide new clues for identifying critical factors that are responsible for pathogenesis.”
In women, the parasite binds to the vaginal lining and is capable of destroying vaginal epithelial cells, which make up the surface of this tissue, Johnson said. This results in vaginitis, with irritation of local tissues. Erosion of cervical tissues may occur, and complications can result in sterility. A big threat from infection also occurs in pregnant women, who are at risk for ruptured membranes, preterm deliveries and low-birth-weight babies. In men, the parasite is a cause of nongonococcal urethritis, but infection is generally asymptomatic and self-limiting.
In both men and women, trichomoniasis is known to increase susceptibility to HIV, the virus that causes AIDS. “In countries where AIDS runs rampant, such as South Africa, the incidence of trichomoniasis is also extraordinarily high, and trichomoniasis is thought to have significantly contributed to the spread of HIV,” Johnson said.