Scientists say they have discovered the genetic pathway by which the malaria parasite moved from gorillas and to infect humans.
The work is being done by Dr Francis Galaway at the Wellcome Sanger Institute, Hinxton, UK, and colleagues at the University of Montpellier, France.
P. falciparum belongs to the malaria parasite family called the Laverania, which originated in African great apes and is the only member of the family that infects humans via zoonosis that took place about 50,000 years ago.
The scientists undertook genome sequencing of all seven Laverania parasite species and found a DNA section that had transferred from a gorilla parasite, Plasmodium adleri, to the ancestor of P. falciparum.
On this DNA sequence is a gene which produces the protein RH5, that can bind to a protein receptor in human red blood cells called basigin, causing infection.
Dr Galaway and colleagues believe that targeting RH5 could form the basis of a malaria vaccine.
The study was published yesterday evening (15 October) in PLoS Biology.
Dr Galaway says: “The fact that this ancestral RH5 protein was able to bind to the red blood cell receptor basigin from both humans and gorillas, immediately provided a molecular explanation for how P. falciparum evolved to infect humans.”
Co-author Dr Franck Prugnolle added: “It’s fascinating to be able to ‘resurrect’ ancestral genes such as the one which allowed Plasmodium falciparum to jump from gorillas to humans. We’ve discovered not only how a species host switch has occurred, but the individual mutation which has then restricted P. falciparum to a single host species.”
Galaway, F. et al. Resurrection of the ancestral RH5 invasion ligand provides a molecular explanation for the origin of P. falciparum malaria in humans. PLoS Biology 15 October 2019; doi: 10.1371/journal.pbio.3000490
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