Study reveals that beneficial bacteria protect against malaria

A research team from the Gulbenkian Institute of Science (IGC) led byMiguel Soares has revealedthat specific components of bacteria residing in the intestine can trigger a natural defense mechanism that blocks the transmission of malaria.

The key component of the process is a sugar molecule called α-gal (alpha-gal), which is produced by the Plasmodium parasite, the agent responsible for malaria, and also by a strain of Escherichia coli bacteria found in the human intestine. Through experiments conducted on mice, Bahtiyar Yilmaz, a PhD student at IGC, discovered that the production of α-gal by these bacteria is sufficient to induce the production of natural anti-α-gal antibodies capable of recognizing the same sugar molecule on the surface of Plasmodium.

Immediately after the parasite is inoculated into the skin by the mosquito that transmits malaria, these antibodies bind to α-gal on the surface of Plasmodium and activate an additional immune system mechanism that kills it before it leaves the skin, preventing it from entering the bloodstream. In doing so, malaria transmission is blocked.

The level of anti-α-gal antibodies, which research has shown to be lower in younger children, may be the factor that differentiates susceptibility to malaria: only a fraction of all adults who are bitten by mosquitoes become infected, in contrast to the exponentially higher susceptibility of children under the age of 3 to 5 to contracting malaria. An estimated 3.4 billion people are at risk of contracting malaria, and WHO data from 2012 indicate that around 460,000 African children died before their fifth birthday.

Research has shown, through experiments conducted on mice, that this protective mechanism can be activated by vaccination against a synthetic α-gal molecule, which is relatively easy to produce and economical. As Miguel Soares explains, "one of the wonders of the protective mechanism we have now discovered is that it can be induced through a standard vaccination protocol, leading to the production of high levels of anti-α-gal antibodies that can bind to and kill the Plasmodium parasite. If we can vaccinate young children against α-gal, many lives can be saved."

Recently published in Cell magazine , the article brings together the results of a study conducted at IGC in collaboration with the National Institute of Allergy and Infectious Diseases ( Maryland, USA), the Institute of Hygiene and Tropical Medicine (Lisbon, Portugal), St Vincent’s Hospital and the University of Melbourne ( Victoria, Australia), the University of Chicago ( Chicago, USA), and the University of Sciences, Techniques and Technologies of Bamako (Bamako, Mali). It was also funded by the FCT, as well as the Bill and Melinda Gates Foundation (USA) and the European Research Council ( ERC).