Association of naturally acquired IgG antibodies against Plasmodium falciparum serine repeat antigen-5 with reduced placental parasitemia and normal birth weight in pregnant Ugandan women: a pilot study.

Plasmodium falciparum infection during pregnancy contributes substantially to malaria burden in both mothers and offspring. Analysis of naturally acquired immune responses that confer protection against parasitemia and clinical disease is important to guide vaccine evaluation as well as identify immune correlates. Unfortunately, few studies have addressed the relationship between immune responses to malaria vaccine candidate antigens and protection against adverse effects on pregnant women and newborn birth weight. This study examines the relationship of maternal antibody responses to serine repeat antigen-5 (SE36) and merozoite surface protein-1 (MSP119 and MSP142) with placental parasitemia and birth weight. In a peri-urban setting in Uganda, pregnant women without placental parasites have high median ODs for antibodies against SE36 (P<0.001). Naturally acquired anti-SE36 IgG was most prevalent in women without placental parasitemia (P<0.001). Furthermore, pregnant women with significantly high levels of anti-SE36 IgG delivered babies with normal birth weights (P<0.001). That antibody to SE36 was associated with both a reduced risk of placental parasitemia and resulting normal birth weight in newborns suggests some protective role. In contrast, although antibody to MSP142 was also associated with reduced placental parasitemia and immune responses to both MSP119 and MSP142 may be of importance, there was no association between anti-MSP119 antibodies and infant birth weight outcomes. This study highlights the need for conducting further studies to investigate the association of antibodies against SE36 and outcomes of malaria infection in pregnant women.