Zika virus infection confers protection against future infection in monkeys, but lingers in the body of pregnant animals for prolonged periods of time, according to research funded by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH). The findings appear in the June 28 issue of Nature Communications. The research team was led by University of Wisconsin-Madison pathology professor David O’Connor. The scientists infected eight rhesus macaque monkeys with the Zika virus strain responsible for the current outbreak in the Americas. Non-pregnant monkeys cleared the virus from their blood approximately 10 days after infection, which is similar to what is seen in humans with Zika virus and other flaviviruses. In the two pregnant monkeys, however, Zika virus persisted in the blood for at least 57 days. The team then re-infected three of the non-pregnant monkeys with the same virus strain 10 weeks later and found they all were protected against infection.
The results indicate that natural immunity may be sufficient to protect against future Zika infections in humans, and a vaccine that can mimic this immunity would likely be safe and provide similar protection, the authors write. The research team will continue to follow the pregnant monkeys to learn why the virus lingers in the body, and how this persistent infection relates to any potential fetal malformations or birth defects.