In vivo protection against ZIKV infection and pathogenesis through passive antibody transfer and active immunisation with a prMEnv DNA vaccine

Significant concerns have been raised owing to the rapid global spread of infection and disease caused by the mosquito-borne Zika virus (ZIKV). Recent studies suggest that ZIKV can also be transmitted sexually, further increasing the exposure risk for this virus. Associated with this spread is a dramatic increase in cases of microcephaly and additional congenital abnormalities in infants of ZIKV-infected mothers, as well as a rise in the occurrence of Guillain Barre’ syndrome in infected adults. Importantly, there are no licensed therapies or vaccines against ZIKV infection. In this study, we generate and evaluate the in vivo efficacy of a novel, synthetic, DNA vaccine targeting the pre-membrane+envelope proteins (prME) of ZIKV. Following initial in vitro development and evaluation studies of the plasmid construct, mice and non-human primates were immunised with this prME DNA-based immunogen through electroporation-mediated enhanced DNA delivery. Vaccinated animals were found to generate antigen-specific cellular and humoral immunity and neutralisation activity. In mice lacking receptors for interferon (IFN)-α/β (designated IFNAR−/−) immunisation with this DNA vaccine induced, following in vivo viral challenge, 100% protection against infection-associated weight loss or death in addition to preventing viral pathology in brain tissue. In addition, passive transfer of non-human primate anti-ZIKV immune serum protected IFNAR−/− mice against subsequent viral challenge. This study in NHP and in a pathogenic mouse model supports the importance of immune responses targeting prME in ZIKV infection and suggests that additional research on this vaccine approach may have relevance for ZIKV control and disease prevention in humans. Zika virus: A DNA vaccine candidate. A Zika virus vaccine candidate has been developed that elicits an immune response and confers protection in animal models. An international team of researchers headed by David Weiner of The Wistar Institute, Philadelphia, USA, generated a DNA-based vaccine candidate using genes encoding for Zika virus surface proteins—with the intent that these genes, when transferred to a host, would produce characteristic proteins allowing the host to recognise and protect against Zika virus infection. Weiner’s team found that their vaccine candidate generated a specific immune cell response in healthy mice, and offered protection to mice genetically engineered to be vulnerable to the virus. Importantly, their vaccine also elicited functional responses in non-human primates, highlighting that further research into this approach is warranted for the immunisation of humans against Zika virus.