 |
| Scientists have found the protozoan T. vaginalis(responsible for a sexually transmitted disease called trichomoniasis) becomes even more dangerous when infected with a parasite. CREDIT: Zuzanae | Shutterstock |
A sexually transmitted parasite that's extraordinarily widespread gets
even more dangerous when infected with a virus, researchers say. Scientists
investigated the sexually transmitted disease trichomoniasis, which is caused by the parasite Trichomonas vaginalis, a type of microbe
known as a protozoan. Rather than invade human cells, the parasite latches onto
their surfaces and feeds on them.
Trichomoniasis is more common than all bacterially sexually transmitted diseases combined, annually affecting nearly 250
million men and women worldwide. People infected with the parasite become
especially vulnerable to other sexually transmitted diseases, including HIV,
which causes AIDS, and HPV, which is linked with cervical and prostate cancers.
In addition, complications from trichomoniasis include miscarriage, preterm
delivery, low birth weight and infertility. "Trichomoniasis is associated
with devastating consequences for women due to inflammation and related risks
of reproductive disease," said researcher Raina Fichorova, a reproductive
immunobiologist at Harvard Medical School and Brigham and Women's Hospital in
Boston.
Parasite-virus duo
Intriguingly, more than 80 percent of these parasites are themselves
infected, with a virus simply dubbed Trichomonasvirus "Unlike flu
viruses, for example, this virus can't spread by jumping out of the cell into
another one," said researcher Max Nibert at Harvard Medical School.
"It just spreads between cells when they [the hosts] divide or mate."
The virus seems to have no detrimental effect on the parasite, and the
widespread nature of this virus led researchers to suspect it might actually
benefit the parasite in some way. To learn more, the researchers collected Trichomonas
from infected women and tested how both virus-infected and virus-free
versions of the parasite affected human cells grown in lab dishes.
Currently, trichomoniasis is most often treated with the antibiotic metronidazole. However, when researchers killed virus-infected Trichomonas with this
drug, they found the dying or injured parasites released viruses that inflamed
the human cells. The virus does not infect the human cells, but it nevertheless
aggravates the harmful effects of the parasite. These findings may explain why
metronidazole does not prevent the harmful effects trichomoniasis can have on women's reproduction, and may actually make things worse — it forces the parasite
to release harmful viruses. "Antibiotic treatment can actually make things
worse by amplifying inflammation," Fichorova said.
Making the body more vulnerable
The inflammation also might help explain why the parasite makes people
more vulnerable to other sexually transmitted diseases (STDs). "The inflammation may destroy or weaken
the barriers that keep other infections out," Fichorova said. Scientists
aren't sure whether the virus actually helps the parasite in some way.
"The virus may change the parasite's makeup — for instance, help generate
proteins on the parasite's surface that may subdue immune response and make the
parasite more acceptable to its host," Fichorova said.
Future research should explore what part of the virus' structure or life
cycle may be most vulnerable to drugs, Fichorova added. "To treat trichomoniasis
safely, we have to not only attack this parasite, but also its virus at the
same time." The scientists detailed their findings online Nov. 7 in the
journal PLOS ONE.
Source: Live Science
Please share
No comments:
Post a Comment