Genome of Trichomoniasis Responsible for Common Sexually Transmitted Infection Sequenced

Trichomoniasis is a sexually transmitted infection that affects both men and women and results in roughly 7.4 million new cases in the United States each year, according to the U.S. Centers for Disease Control and Prevention.

Both men and women with trichomoniasis have an increased susceptibility to HIV infection and may transmit HIV to their sexual partners. Pregnant women with trichomoniasis may deliver a low birthweight (less than five pounds) or premature infant. Although the prescription drugs metronidazole and tinidazole usually cure trichomoniasis, drug resistance has become an increasing concern.
In generating the genetic blueprint for the parasite, researchers were surprised to find such a large and highly repetitive genome comprising nearly 26,000 predicted genes as determined by computer models and previously sequenced parasitic genomes. Repetitive genes accounted for roughly 65 percent of the genome. Although it is not entirely clear why the genome is so large and repetitive, researchers theorize that the parasite evolved over time, previously inhabiting the intestine and later moving to the urogenital tract, which resulted in increased cell size and, subsequently, a considerably expanded genome.

The researchers also discovered more than 150 instances where bacterial genes may have transferred into the parasite’s genome, suggesting that bacteria may have influenced the development of the parasite’s metabolism. The decoded genome also revealed 800 genes for surface proteins that likely enable T. vaginalis to adhere to cells in the urinary and genital tracts and cause infection. Additionally, the researchers were able to analyze proteins thought to be linked to the parasite’s hydrogenosome--its energy source and the target of the two drugs approved to treat trichomoniasis--and identified possible ways the parasite may become resistant to these medications. Understanding how T. vaginalis causes infection and developing methods to prevent it could also help curb the transmission of other STIs often found in connection with trichomoniasis, including chlamydia and gonorrhea, according to the researchers.

The study is detailed in the January 12 issue of Science .

CONTACT:
Kathy Stover
301-402-1663

Message posted by: Rashmi Nemade