Plasmodium falciparum Inhibitory Capacities of Paired Maternal-cord Sera from South-west Province, Cameroon

Abstract

In malaria endemic areas, young children are protected against malaria attack during the first few weeks of life partially by transplacentally acquired antibodies. In this study, we show, using an in vitro assay, that part of these antibodies are involved with blocking the re-invasion of host red blood cells by erythrocytic merozoites. One hundred consecutive paired maternal-cord blood samples were collected at delivery and their plasma assayed for total IgG antibodies against crude blood stage antigens by the ELISA. The Ig fraction were precipitated from the plasma samples with (NH(4))(2)SO(4), purified on PD10 columns and used in vitro in determining the re-invasion inhibitory capacities. The mean (+/-SD) ELISA OD(405) IgG antibodies to crude blood stage antigens of maternal (0.476 +/- 0.48) and cord (0.421 +/- 0.39) plasma samples was not significantly different. However, the mean total protein concentration of the Ig fractions for maternal samples (15.82 +/- 3.85) was significantly higher (p=0.005) than that of paired cord samples (12.87 +/- 2.86 mg/ml). There was no correlation between anti-Plasmodium falciparum-specific IgG levels and total protein concentrations of the Ig fractions of both maternal and cord samples. The entire test Ig fractions were strongly inhibitory (>50 per cent) except for four paired maternal cord samples, which were moderately inhibitory (21--50 per cent) at the highest concentration tested (1:2 dilution). Furthermore, there was no correlation between maternal IgG levels and percentage re-invasion inhibition at the 1:2 dilution. The results suggest that mothers resident in malaria endemic areas possess naturally acquired re-invasion inhibitory antibodies and their foetuses can acquire these antibodies transplacentally, which may contribute to the relative protection observed in infants during their first few weeks of life.

Malaria Risk Factors in Women on Intermittent Preventive Treatment at Delivery and Their Effects on Pregnancy Outcome in Sanaga-Maritime, Cameroon

“…Therefore, there is a need for continuous monitoring of IPT p . Some studies on pregnancy associated malaria risk factors and effects [11], [12], [13], immunological response [14], [15], [16] and diagnostic methods [10] have been conducted in the country. However, benefits of IPT p -SP as well as malaria risk factors and their effects on mothers and newborns at delivery have not been documented in the Sanaga-Maritime Division.…”

Transplacental transfer of total immunoglobulin G and antibodies to Plasmodium falciparum antigens between the 24th week of gestation and term

“…Antibody concentration has an impact on transplacental transfer 8,[25][26][27] . Calculations from 6 studies in westernized countries, at term mothers averaged (± SEM) 10.5 ± 1.8 ml/ml IgG, cord blood had 12.8 ± 1.3 mg/ml, resulting in CMR ratios of 1.2 ± 0.2 14,22,23,[28][29][30] In comparison, calculations based on data from 9 African studies for mothers averaged 17.3 ± 3.1 mg/IgG, cord blood 14.7 ± 2.5 mg/ml, with CMR of 0.85 ± 0.1 5,13,14,16,[30][31][32][33][34] . Thus, African newborns have higher IgG levels that babies in westernized countries, but CMR are lower due to elevated maternal IgG.…”