# Zika virus infection in early pregnancy increases the likelihood of persistent neutralizing antibodies

## TL;DR

Zika virus infection during early pregnancy leads to long-lasting antibodies in mothers but not in their children, suggesting limited postnatal protection.

## Contribution

This study reveals the long-term persistence of Zika virus neutralizing antibodies in mothers, particularly those infected in the first trimester, and highlights limited antibody transfer to children.

## Key findings

- 66.2% of mothers had detectable Zika virus neutralizing antibodies 3–4 years after infection.
- Only 2.8% of children had detectable neutralizing antibodies after maternal antibodies waned.
- Maternal antibody titers were not clearly linked to adverse child outcomes.

## Abstract

Neutralizing antibodies (nAbs) play a central role in protection against Zika virus (ZIKV) infection. Higher maternal ZIKV nAb titers during pregnancy have been associated with reduced risk of congenital anomalies. However, limited data exist on the long-term persistence of these antibodies in women infected during pregnancy and in children exposed in utero.

We conducted a cross-sectional serological study using stored serum samples from a cohort of mother–child pairs with confirmed maternal ZIKV infection during pregnancy in Campo Grande, Brazil. ZIKV nAb titers were measured in samples collected approximately 3–4 years after maternal infection using plaque reduction neutralization testing. Among 77 women, 66.2% (51/77) had ZIKV nAbs above the cutoff point, with higher titers observed in patients with first trimester infection. In contrast, only 2 of 72 children (2.8%) presented detectable ZIKV nAbs following clearance of maternal antibodies. No clear association was found between maternal nAb titers and adverse child outcomes.

Our findings suggest long-term persistence of neutralizing antibodies in most women infected with ZIKV during pregnancy, especially when infection occurred in the first trimester of pregnancy ZIKV-specific nAb persistence was rare in children with antenatal exposure once maternal antibodies waned, reinforcing concerns about limited postnatal protection in this group. These results underscore the importance of further studies to clarify the role of neutralizing antibodies in long-term protection and disease pathogenesis, particularly in endemic regions where the risk of reinfection or exposure to related arboviruses remains high.

Zika virus (ZIKV) infection during pregnancy can cause serious birth defects, and maternal neutralizing antibodies (nAbs) are thought to play a key role in protection. However, little is known about how long these antibodies last in mothers and their children after infection. In this study, we analyzed blood samples from women infected with ZIKV during pregnancy and their children, collected 3–4 years later. We found that most mothers still had detectable ZIKV nAbs, especially those infected in the first trimester. In contrast, very few children had these antibodies after maternal antibodies naturally disappeared, suggesting they may not have long-term protection against ZIKV. Our findings highlight the need for further research to understand how these antibodies affect protection and disease risks, particularly in regions where Zika and related viruses remain a threat. This work helps inform vaccination strategies and long-term care for children exposed to ZIKV before birth.