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Howard Hughes Medical Institute

Study: Zika Virus Lives in Vagina Long After Infection


Just when you didn’t think it could get any worse, it gets worse.

A recent Yale University study discovered that the Zika virus may live in the vagina for days after infection. Researchers studied the vaginal tissue of pregnant lab mice several days after infection, the virus spread and infected the fetal brain and development but it also replicated itself robustly in the female reproductive tract more than at other sites of infection. The consequence of that rapid replication could be dire for reproduction.

The study was published online August 25, 2016 in Cell.

Before this report, it was not known whether the Zika virus replicated in the vagina after women were exposed through sexual intercourse. Also unknown was the potential consequences on fetuses after sexual transmission to pregnant women were also unknown.  Recent reports have confirmed sexual transmission of the Zika virus from infected men to uninfected women.

The researchers found that the Zika virus replicated in the vagina and persisted post-infection.

“We saw significant virus replication in the genital tissue, up to 4-5 days. With other routes of infection, theZika virus does not replicate unless you block type I interferons. What surprised us most was that the virus replicated in the vagina of wild-type mice with intact interferon response,” said Akiko Iwasaki, professor of immunobiology and investigator of the Howard Hughes Medical Institute. “The finding may be important for women, not only pregnant women,” said Iwasaki. “The vagina is a site where the virus can replicate and possibly transmit to partners. In pregnant women, vaginal transmission of Zika virus may have a significant impact on the developing fetus.”

The study is also significant given the fact that, according to reports, Zika virus can also persist in semen up to 180 days post-infection, notes the Yale researcher. In addition, a recent report indicates that there can be a female-to-male transmission of Zika virus after vaginal intercourse. Combined, these studies paint a broader picture about the virus generally for those trying to eradicate and prevent it from spreading.

Other Yale authors include Laura Yockey, Luis Varela, Tasfia Rakib, William Khoury-Hanold, Susan L. Fink, Bernardo Stutz, Klara Szigeti-Buck, Anthony Van den Pol, Brett D. Lindenbach, and Tamas L. Horvath. The work was supported by the Howard Hughes Medical Institute, and the National Institutes of Health.