Chapter 13 - Zika virus

Abstract

Following the 2015–2016 Zika virus (ZIKV) epidemic in the Americas, ZIKV, a previously under recognized arboviral flavivirus, emerged as a global health threat, given its severe teratogenic effects on the developing fetal central nervous system (CNS) and its association with Guillain-Barré syndrome. Although Zika cases have declined subsequently globally, outbreaks may resurface, underscoring a pressing need for vaccine development to curtail the risk to pregnant mother-infant pairs in years to come. Although most people with ZIKV infection recover without complications, ZIKV in pregnancy may cause a spectrum of fetal/infant CNS abnormalities, including microcephaly. ZIKV differs from other arboviruses in that it also is sexually transmitted, allowing potential for further spread, even to women who have not traveled to endemic areas themselves. Despite challenges to development of vaccines that protect against a congenital infection, there are presently multiple ZIKV vaccine candidates in different stages of development. These encompass nucleic acid vaccines (4 in advanced stages of development), inactivated whole virus vaccines (four also in development), live attenuated measles vector vaccine and a vaccine that targets mosquito salivary antigens (a universal mosquito-borne disease vaccine). Common targets for ZIKV vaccines include the ZIKV premembrane (prM) and envelope (E) proteins, which represent multiple surface epitopes easily accessible to antibodies. To date six vaccine trials have published preliminary findings; all appear to show strong immune responses with only mild to moderate adverse reactions reported. Subunit proteins and virus-like particle vaccines, live attenuated flavivirus chimeric vaccines, and adenovirus-vectored vaccines, have shown promising results in animal models.