• Andrew Teo, Wina Hasang, Louise M Randall, Gaoqian Feng, Lauren Bell, Holger Unger, Christine Langer, James G Beeson, Peter M Siba, Ivo Mueller, Malcolm E Molyneux, Graham V Brown, and Stephen J Rogerson.
• Department of Medicine Doherty Institute.
• J. Infect. Dis. 2014 Nov 1; 210 (9): 1444-55.

BackgroundAs malaria control is intensified, pregnant women may be less exposed to malaria, thus affecting the acquisition of protective antibody.MethodsPlasma samples were collected from Malawian and Papua New Guinean (PNG) pregnant women enrolled over 7-year periods, during which malaria prevalence fell by over two thirds. Immunoglobulin G (IgG) levels to schizont extract, merozoite antigens, and VAR2CSA-DBL5ε were measured by enzyme-linked immunosorbent assay (ELISA). Levels of IgG to variant surface antigens of infected erythrocytes (IEs) and merozoites and levels of opsonizing IgG to IEs were measured by flow cytometry.ResultsIn both settings, levels of antibodies in pregnant women to recombinant antigens and to intact IEs but not of opsonizing antibodies decreased over time. After adjustment for coverage with insecticide-treated bed nets (ITNs), these differences disappeared in the Malawian cohort, whereas in the PNG cohort, time was independently associated with a decrease in several antibody responses measured by ELISA.ConclusionsThe impact of falling parasite prevalence on anti-Plasmodium falciparum serological indicators in pregnant women varies by setting. Increased ITN coverage may affect development of antibodies to recombinant antigens, but levels of opsonizing IgG remained stable over time. Opsonizing IgG against placental-binding IEs may persist, thus offering longer-lasting protection against malaria during pregnancy.© The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

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