NIAID Now | January 25, 2019
Malaria caused by infection with Plasmodium falciparum (P. falciparum) parasites kills up to 300,000 children in sub-Saharan Africa each year. In areas where malaria is widespread, children suffer the most from the disease, particularly when they are more than 6 months old. Researchers have known for decades that newborns and young infants in these areas are relatively resistant to malaria infection and to severe malaria, and they have speculated that this resistance is due to antibodies from the mother.
Following up on earlier findings, NIAID-funded researchers and their colleagues in NIAID’s Laboratory of Malaria Immunology and Vaccinology investigated whether antibodies that target a P. falciparum protein called PfSEA-1 are transferred from mother to child during pregnancy, and whether these antibodies are associated with a reduced severity of malaria in the infants.
The researchers studied 647 mother-child pairs in northeastern Tanzania. They collected umbilical cord blood samples from the infants when they were born and followed the children every 2 weeks from birth until they were 1 year old. In the 583 infants with complete follow-up data, the researchers found that anti-PfSEA-1 antibodies in cord blood, but not antibodies to several other P. falciparum proteins, were associated with a reduced risk of severe malaria at ages 9 and 12 months. Infants with the highest levels of anti-PfSEA-1 antibodies had 51.4 percent fewer cases of severe malaria in their first year of life than infants with lower levels of these antibodies.
The team also looked at whether anti-SEA-1 antibodies can protect newborns from malaria in an experimental mouse model of malaria. They vaccinated female mice with SEA-1A from a malaria parasite that infects rodents to generate anti-SEA-1 antibodies, mated the mice, and exposed the newborn mice (pups) to malaria. Pups born to SEA-1–vaccinated mothers had significantly lower blood levels of malaria parasites and survived longer than pups born to non-vaccinated mothers. Furthermore, several of the pups born to vaccinated mothers appeared to be cured of malaria after becoming infected.
Together, these study findings are the first demonstration that antibodies to a malaria protein, SEA-1, from the mother can confer resistance to severe malaria or death in the offspring. The results also suggest that vaccinating pregnant women with PfSEA-1 could help their infants survive malaria infection.
Reference: Maternally derived antibodies to schizont egress antigen-1 and protection of infants from severe malaria. Kurtis JD et al. Clinical Infectious Diseases. 2018 Aug 25. [published online ahead of print]