092: A new type of malaria vaccine utilizing the mosquito immune system with Carolina Barillas-Mury

To eliminate malaria, you have to stop transmission, and that's what Carolina Barillas-Mury hopes to do. Her work on the interaction of the malaria parasite Plasmodium falciparum may lead to a transmission-blocking vaccine. She explains how, and discusses the co-evolution of malaria, mosquitos, and man.

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Julie's Biggest Takeaways:

When born, babies carry antibodies from their mothers, which may protect them through passive immunity; additionally, babies are more easily protected from mosquito exposure by placing them under bed netting. As they grow, children become more active, and their passive immunity concurrently wanes. They may be exposed to mosquitoes carrying malaria parasites and their still-developing immune systems aren't able to keep the parasites from replicating, leading to more severe disease, including cerebral malaria.

The Culicines and Anopholines are two major groups of mosquitoes that carry disease. The culicines have recently spread around the world, but the Anopholines species moved from Africa into South America one hundred million years ago, but malaria only moved into the New World a few hundred years ago with the slave trade. The relationship between the mosquitoes and malaria parasites has been evolving much longer in Africa than it has been with the specific population of mosquitoes in South America - one of the reasons why the disease is less devastating in South America.

The 'invisibility gene,' pfs47, is expressed in the banana-shaped ookinete and helps the malaria parasite to avoid detection by the mosquito immune system. The pfs47 malarial gene is adapted for the localized mosquito populations from the same region as the parasite; if an African mosquito is infected with a South American parasite, the parasite is more likely to be recognized and killed than if the African mosquito is infected with an African parasite.

The most immunogenic proteins in parasites may produce an immune response, but this immune response may not block infection. New vaccines are concentrating on where antibodies bind, to ensure there is a biological effect of the immune response, and this is why Barillas-Mury has used a modified Pfs47 protein to generate immune responses, rather than its native form.

Links for this Episode:

• Carolina Barillas-Mury NIAID website
• NPJ Vaccines: Antibody Targeting of a Specific Region of Pfs47 Blocks Plasmodium falciparum Malaria Transmission.
• PLoS One: Molecular Analysis of Pfs47-Mediated Plasmodium Evasion of Mosquito Immunity.
• PNAS: Plasmodium Evasion of Mosquito Immunity and Global Malaria Transmission: The Lock-and-Key Theory.
• HOM Tidbit: History of the Discovery of the Malaria Parasites and their Vectors
• MTM Listener Survey