SAN DIEGO (GenomeWeb News) — Scientists at the National Institute of Allergy and Infectious Diseases have sequenced the genome of a parasite that causes trichomoniasis, a common sexually transmitted disease, NIAID said yesterday.
According to the researchers, the genome of Trichomonas vaginalis is made up of 160 megabases and nearly 26,000 predicted genes. The scientists said they were surprised by its size.
Jane Carlton, a researcher who worked with The Institute for Genomics Research and the report’s lead author, noted that “Parasites generally have smaller amounts of DNA than non-parasitic organisms, but in this case, there was 10 times as much DNA than we originally thought. … ”
About two-thirds of the genome is made up of repeats and transposables, which “reflects a recent massive expansion of genetic material,” according to the authors. They suggest this sudden expansion may have happened when the parasite adapted from life in the intestines to one in the urogenital region.
The researchers found more than 150 instances of bacterial genes transferring into the T. vaginalis genome, and also found 800 genes for surface proteins that may enable the parasite to stick to cells in the urinary and genital tracts. genome, and also found 800 genes for surface proteins that may enable the parasite to stick to cells in the urinary and genital tracts.
The scientists also managed to analyze proteins they believe may be connected to the parasite’s hydrogenosome, which also is the target of two drugs used to treat the trichomoniasis. They also discovered possible ways the parasite may develop resistance to those medications.
According to the Centers for Disease Control and Prevention, there are roughly 7.4 million new cases of trichomoniasis in men and women in the US each year. The disease causes vaginal irritation and other symptoms in women, and irritation and other symptoms in the urethra in men. The disease also heightens the risk of contracting HIV.
Details of the project were published in the Jan. 12 issue of Science.