Summary: A new study investigates how the ZIKA virus can be sexually transmitted between male and female mice, and how the virus can pass vertically from mother to fetus.
Study analyzes how virus is spread sexually and from mother to fetus.
National Institutes of Health (NIH) scientists have developed a mouse model to study Zika virus transmitted sexually from males to females, as well as vertically from a pregnant female to her fetus. They are using the model to study how and when the virus is spread, including how the virus crosses the placenta, as well as to investigate potential treatments to block virus transmission.
Scientists from NIH’s National Institute of Allergy and Infectious Diseases developed the model, which was challenging because mice naturally defend against Zika virus better than people because they have a stronger interferon response. Interferon is a powerful antiviral protein that inhibits the virus. The researchers suppressed the interferon in specialized laboratory mice that also lack the ability to produce T cells or B cells. These mice, called anti-interferon Rag (AIR) mice, have prolonged virus infection in the testes, akin to Zika-infected men. This attribute allowed the investigators to study sexual transmission from male to female mice, which occurred frequently.
In addition to sexual transmission, the researchers also showed that Zika virus was transmitted vertically from pregnant AIR mice to their fetuses. The researchers found that only some fetuses from each female were infected with virus, suggesting that the placenta may be the most important barrier in preventing Zika virus from reaching the fetus. The group also found that the virus could be detected in fetal tissues other than mouse brain tissue, such as the lymph nodes. Studying how Zika virus is spread in mouse fetuses may help us understand how Zika infection leads to various birth defects in people.
In addition to sexual transmission, the researchers also showed that Zika virus was transmitted vertically from pregnant AIR mice to their fetuses. NeuroscienceNews.com image is for illustrative purposes only.
Although Zika virus usually does not cause illness in people, the virus can cause birth defects when an infected pregnant woman transmits it to her fetus. While there are no licensed vaccines or treatments available for Zika virus, many candidates are in various stages of development.
Funding: The study was funded by the NIH/National Institute of Allergy and Infectious Diseases.
Source: Ken A Pekoc – NIH/NIAID
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Full open access research for “Sexual and Vertical Transmission of Zika Virus in anti-interferon receptor-treated Rag1-deficient mice” by Clayton W. Winkler, Tyson A. Woods, Rebecca Rosenke, Dana P. Scott, Sonja M. Best & Karin E. Peterson in Scientific Reports. Published online August 3 2017 doi:10.1038/s41598-017-07099-7
Sexual and Vertical Transmission of Zika Virus in anti-interferon receptor-treated Rag1-deficient mice
Although Zika virus (ZIKV) is primarily transmitted to humans by the Aedes aegypti mosquito, human-to-human transmission has also been observed from males-to-females as well as mother-to-offspring. In the current study, we studied both sexual transmission (STx) and vertical transmission (VTx) of ZIKV using anti-IFNAR1-treatment of Rag1−/− (AIR) mice. These mice have suppressed type I IFN responses and lack adaptive immune responses, leading to a prolonged infection prior to clinical disease. STx of ZIKV from infected AIR males to naive Ifnar1−/− females was observed with greater than 50% incidence, with infection observed in the vaginal tract at early time points. In the case of a resulting pregnancy, virus was also found in the uterus and placental tissue. In additional studies, VTx of virus was observed in AIR female mice. Specifically, peripheral ZIKV infection of pregnant AIR females resulted in detectable virus in brain and/or lymph nodes of fetuses and/or pups. VTx of ZIKV was stochastic, in that not all fetuses/pups within the same dam had detectable virus and infection was not associated with breakdown of maternal/fetal placental barrier. This provides a new model to study the barriers to STx and VTx of ZIKV and the immune responses essential to preventing transmission.
“Sexual and Vertical Transmission of Zika Virus in anti-interferon receptor-treated Rag1-deficient mice” by Clayton W. Winkler, Tyson A. Woods, Rebecca Rosenke, Dana P. Scott, Sonja M. Best & Karin E. Peterson in Scientific Reports. Published online August 3 2017 doi:10.1038/s41598-017-07099-7