Scientists Decode Tiny STD Bug With Huge Genome

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Main Category: Genetics
Also Included In: Sexual Health / STDs;  Women's Health / Gynecology;  Men's health
Article Date: 12 Jan 2007 - 9:00 PDT

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Scientists have managed to decode the genome of the common but overlooked sexually transmitted pathogen Trichomonas vaginalis.

The project is reported in the journal Science.

This no mean feat was the effort of an international team of 65 scientists led by Jane M. Carlton working for the Institute for Genomic Research in Rockville, Maryland, and who is currently at the Department of Medical Parasitology at the New York University School of Medicine.

T. vaginalis is a parasite that colonizes the urogenital tract in men and women. It causes the sometimes painful infection Trichomoniasis, and according to the US Centers for Disease Control and Prevention (CDC), it is the most common curable sexually transmitted disease (STD) in young women who are sexually active. The CDC estimates there are 7.4 million new cases every year, in both men and women. In women it can cause vaginitis and cystitis, and in men it can cause urethritis and prostatitis, although men often do not have symptoms at all.

The scientists think that the parasite may at one time many millions of generations ago have lived in the gut and migrated to the genital area because it gave it a higher survival advantage. It has had an interesting evolution, because to survive it has probably absorbed into its genome pieces of genetic material from rival bacteria and organisms.

Much of the genome is the same basic pattern repeated over and over with minor variations. The scientists have decoded the genome in sections, and according to Dr. Carlton, they don't have the computer algorithms to put it back together again it is so large.

T. vaginalis has ten times more genetic material than its rivals - so far it has 26,000 confirmed genes - this is already more than in the human genome which has about 25,000. The research team estimated there could be 34,000 genes altogether.

T. vaginalis is the most common nonviral sexually transmitted disease, "bigger than chlamydia, syphilis or gonorrhea," says Dr. Carlton, who suggests that it may be overlooked because most infections are symptomless and in men in particular.

When they do manifest, the symptoms can show as discharge and pain when passing water or during sex.

It is hoped that these results will help research and improve treatments. About 5 per cent of infections are resistant to treatments.

"Draft Genome Sequence of the Sexually Transmitted Pathogen Trichomonas vaginalis"
Jane M. Carlton, Robert P. Hirt, Joana C. Silva, Arthur L. Delcher, et al.
Science 12 January 2007: Vol. 315. no. 5809, p. 158
DOI: 10.1126/science.315.5809.158g

Trichomoniasis - CDC Fact Sheet (US)

The institute for Genomic Research

Written by: Catharine Paddock
Writer: Medical News Today
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today