During pregnancy a variety of immunological changes occur to accommodate the fetus. It is unknown whether these changes continue to affect humoral immunity postpartum or how quickly they resolve. IgG levels were measured to P. falciparum and P. vivax antigens in 201 postpartum and 201 controls over 12 weeks. Linear mixed-effects models assessed antibody maintenance over time and the effect of microscopically confirmed Plasmodium spp. infection on antibody levels, and whether this was different in postpartum women compared with control women. Postpartum women had reduced Plasmodium spp. antibody levels compared to controls at baseline. Over 12 weeks, mean antibody levels in postpartum women increased to levels observed in control women. Microscopically confirmed P. falciparum and P. vivax infections during follow-up were associated with an increase in species-specific antibodies with similar magnitudes of boosting observed in postpartum and control women. Antibodies specific for pregnancy-associated, VAR2CSA-expressing parasites did not rapidly decline postpartum and did not boost in response to infection in either postpartum or control women. After pregnancy, levels of malaria-specific antibodies were reduced, but recovered to levels seen in control women. There was no evidence of an impaired ability to mount a boosting response in postpartum women.
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This work was supported by the National Health
and Medical Research Council of Australia (project grant (#1049213) to FF; training award to FF; Infrastructure
for Research Institutes Support Scheme Grant; Senior Research Fellowship to JS and JB); Australian Research
Council (Future Fellowship to FF); Victorian State Government Operational Infrastructure Support (grant
to the Burnet Institute); The Christophe and Rodolphe Mérieux Foundation (prize (2008) to FN); Australian
Government (Australian Postgraduate Award to AM); SMRU is part of the Mahidol Oxford University Tropical
Medicine Research Unit supported by the Wellcome Trust of Great Britain.