Impact of maternally derived antibodies to Plasmodium falciparum Schizont Egress Antigen-1 on the endogenous production of anti-PfSEA-1 in offspring

Abstract Background We evaluated whether maternally-derived antibodies to a malarial vaccine candidate, Plasmodium falciparum Schizont Egress Antigen-1 ( Pf SEA-1), in cord blood interfered with the development of infant anti- Pf SEA-1 antibodies in response to natural exposure. Methods We followed 630 Tanzanian infants who were measured their antibodies against Pf SEA-1 (aa 810-1023; Pf SEA-1A) at birth and 6, 12, 18, and 24 months of age, and examined the changes in anti- Pf SEA-1A antibody levels in response to parasitemia, and evaluated whether maternally-derived anti- Pf SEA-1A antibodies in cord blood modified infant anti- Pf SEA-1A immune responses. Results Infants who experienced parasitemia during the first 6 months of life had significantly higher anti- Pf SEA-1A antibodies at 6 and 12 months of age compared to uninfected infants. Maternally-derived anti- Pf SEA-1A antibodies in cord blood significantly modified this effect during the first 6 months. During this period, infant anti- Pf SEA-1A antibody levels were significantly associated with their P. falciparum exposure when they were born with low, but not higher, maternally-derived anti- Pf SEA-1A antibody levels in cord blood. Nevertheless, during the first 6 months of life, maternally-derived anti- Pf SEA-1A antibodies in cord blood did not abrogate the parasitemia driven development of infant anti- Pf SEA-1A: parasitemia were significantly correlated with anti- Pf SEA-1A antibody levels at 6 months of age in the infants born with low maternally-derived anti- Pf SEA-1A antibody levels in cord blood and borderline significantly correlated in those infants born with middle and high levels. Conclusions Maternal vaccination with Pf SEA-1A is unlikely to interfere with the development of naturally acquired anti- Pf SEA-1A immune responses following exposure during infancy.