Editors' ChoiceInfectious Disease

Zika meets its match

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Science Translational Medicine  13 Jul 2016:
Vol. 8, Issue 347, pp. 347ec112
DOI: 10.1126/scitranslmed.aah3546

The Zika virus has come to dominate public and scientific consciences, and has already had substantial political, social, and economic impacts. Clinically, Zika has been shown to drive fetal microcephaly and other birth defects. Discovering a vaccine for those at risk—especially in the Americas, the current epicenter of the epidemic—is of the utmost importance. Now, Larocca and colleagues have taken a major step toward this goal by describing a vaccine that protects mice from certain strains of Zika. Turning to strategies previously deployed against other flaviviruses, the authors generated a series of plasmid DNA vaccines expressing either full-length Zika premembrane and envelope (prM-Env) or several partial deletions. Immunization of Balb/c mice with all variants resulted in substantial antibody titers against Zika envelope protein, although only the full prM-Env plasmid vaccine, which yielded the highest antibody levels in blood, completely protected against challenges with Brazilian and Puerto Rican viral strains. Full immunity to both challenges was also observed in C57BL/6 mice, but only to the Brazilian strain in SJL mice. Antibody titer was a strong predictor of efficacy, and in fact giving vaccine-naïve mice IgG antibodies isolated from immunized mice was sufficient to block Zika infection. In support of antibody-mediated prophylaxis, depletion of CD4+ and/or CD8+ T cells had no effect on protection. Additionally, the authors confirmed that a purified inactivated virus vaccine was also effective, although more so if delivered intramuscularly versus subcutaneously. Overall, these preclinical data suggest exciting possibilities for a long-awaited Zika vaccine, especially for pregnant women, given clinical precedent for the relative safety of plasmid DNA and inactivated virus vaccines.

R. A. Larocca et al., Vaccine protection against Zika virus from Brazil. Nature 10.1038/nature18952 (2016). [Full Text]

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