Glycans such as α-gal expressed by bacteria can elicit specific antibody production, and indeed humans often have high concentrations of such antibodies in their circulation. In Cell, Soares and colleagues show that antibodies to α-gal (anti-α-gal) can be protective in malaria (infection with Plasmodium species). During the malaria season, Malian children with higher concentrations of anti-α-gal have a lower incidence of infection. Indeed, Plasmodium sporozoites have on their surface α-gal that can be bound by these antibodies. A mouse model shows that the production of anti-α-gal depends on the presence of the gut microbiota, and specific reconstitution of germ-free mice with bacteria rich in α-gal generates anti-α-gal protective against Plasmodium infection. Depending on the isotype, anti-α-gal protect via complement fixation and/or by opsonization. Protection mediated by anti-α-gal seems to operate specifically at the early stages of exposure to Plasmodium by blocking the infection of hepatocytes.

Cell 159, 1277–1289 (2014)