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Prior asymptomatic Zika infection protects against reinfection in pregnant mice

Protective antibodies in blood could indicate whether expecting mothers have lower infection risk

PLOS

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IMAGE: In this photo, Zika virus infection kills non-human primate epithelial cells. White gaps in the image show where Zika virus has disrupted a layer of healthy cells. Researchers analyzed infection... view more 

Credit: Turner LH, et al. (2017)

Protective antibodies from prior asymptomatic Zika infection defend against reinfection during pregnancy in mice, according to new research published in PLOS Pathogens.

An expecting mother infected with Zika risks passing the virus to her unborn fetus, which can result in birth defects, such as microcephaly, or fetal death. Several other viral diseases are known to pose less risk of infection during pregnancy if the mother previously experienced infection. However, whether this is the case for Zika has been unclear.

To investigate this question, Lucien Turner of Cincinnati Children's Hospital Medical Center, Ohio, and colleagues performed experiments in mice. Pregnant mice, some of which had previously experienced asymptomatic Zika infection, were exposed to the virus.

After Zika exposure, the researchers analyzed tissue from the mouse mothers and their fetuses. They found significantly lower levels of Zika RNA in the tissues of previously infected mice than in those infected for the first time. Similarly, Zika RNA levels were much lower in fetal tissue from the previously infected mice.

Additionally, blood and fetal tissue from the previously infected mice contained high levels of Zika-specific antibodies capable of neutralizing the virus in a laboratory setting. This suggests that prior infection triggered production of Zika-neutralizing antibodies that continued to protect both the mother and the fetus during pregnancy. Interestingly, antibodies from mice previously infected with one strain of Zika were capable of neutralizing both that strain and other Zika strains.

If similar protection occurs in human mothers, these findings could potentially inform efforts to protect pregnant mothers and their fetuses in locations with elevated risk of Zika infection. For instance, a strategy could be developed to identify expecting mothers without high levels of Zika-neutralizing antibodies in their blood who could therefore be at greater risk of infection during pregnancy.

"Pregnancy confers unique susceptibility to Zika virus and other microbes that cause prenatal infection," the authors explain. "This study suggest that women with resolved Zika virus infection have built-up immunity that protects them and their fetal offspring against re-infection during pregnancy."

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In your coverage please use this URL to provide access to the freely available article in PLOS Pathogens: http://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1006684

Citation: Turner LH, Kinder JM, Wilburn A, D'Mello RJ, Braunlin MR, Jiang TT, et al. (2017) Preconceptual Zika virus asymptomatic infection protects against secondary prenatal infection. PLoS Pathog 13(11): e1006684. https://doi.org/10.1371/journal.ppat.1006684

Funding: This work is supported, in part, by the NIH-NIAID through awards R01-AI100934 and R01-AI120202, the March of Dimes Foundation, HHMI Faculty Scholars program, and Burroughs Wellcome Fund Pathogenesis of Infectious Disease award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Competing Interests: The authors have declared that no competing interests exist.

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