Durable cellular immune response against inactivated ZIKV and envelope proteins in ZIKV-infected women during pregnancy

IntroductionZika virus (ZIKV) infection has been associated to Guillain-Barré syndrome in adults and congenital malformations during pregnancy, leading to the manifestation of congenital Zika syndrome (CZS). The ZIKV envelope protein (EZIKV), prominently displayed on the virus surface, is a primary target for the humoral immune response. However, limited information exists regarding its capacity to induce cellular immunity, particularly in pregnant women with a history of ZIKV infection. The EZIKV protein comprises three domains: the central domain (EDI), a dimerization domain (EDII), and a domain responsible for binding to the cell surface receptor (EDIII). To examine the regions of EZIKV targeted by cellular immunity, we examined cellular immune responses in a cohort of mothers infected with ZIKV, whose infants exhibited microcephaly.MethodsTo assess the ZIKV-specific response, we used inactivated virus and different recombinant viral envelope proteins (EZIKV, EDI/IIZIKV and EDIIIZIKV). All women in the study contracted the infection during pregnancy, with 72% experiencing symptoms such as fever, rash, joint pain, and retro-orbital pain. Peripheral blood mononuclear cells (PMBC) were collected post- ZIKV diagnosis confirmation, with a median time of 18 months (IQR 13.5-19) after parturition. Using the ELISpot assay, we quantified specific interferon-gamma (IFNγ) producing cells by stimulating PBMC with either inactivated ZIKV particles or equimolar amounts of recombinant EZIKV, EDI/IIZIKV and EDIIIZIKV.Results and discussionOur findings demonstrate the induction of IFN-γ producing cells in PBMC from ZIKV-convalescent mothers, whose infants manifested microcephaly, upon stimulation with both inactivated ZIKV particles and recombinant proteins. The identification of immunodominant regions within ZIKV can contribute for the development of targeted treatments and vaccine candidates tailored for pregnant women.