Zika virus infection during pregnancy and vertical transmission: case reports and peptide-specific cellmediated immune responses.

Abstract Zika virus (ZIKV) infection in pregnant women is associated with birth defects which are more prevalent and severe the earlier in pregnancy the infection occurs. Pregnant women at risk of possible ZIKV exposure (n = 154) were screened using ELISA for ZIKV IgM and IgG. Plaque reduction neutralization tests (PRNT) confirmed ZIKV infection in 9 cases (5.84%). Two cases of vertical ZIKV transmission were confirmed by PCR. One infant showed no signs of birth defects and had a normal developmental profile despite first trimester maternal infection. In the second case, pregnancy was terminated. Production of interferon-γ (IFN-γ) by peripheral blood mononuclear cells obtained from pregnant women and umbilical cord blood was measured using enzyme-linked immunospot assay (ELISpot) following stimulation with panels of synthetic peptides derived from the sequence of ZIKV proteins. This analysis revealed that among all peptide pools tested, those derived from the ZIKV envelope protein generated the strongest IFN-γ response.