Malaria parasite doesn’t pass drug immunity to its offspring

Malaria parasites may build up a genetic tolerance to an antimalarial drug, but they can’t spread that resistance to future generations, researchers report in the April 15 Science.

Malaria parasites can develop mutations in the cytochrome b gene that make them resistant to a drug called atovaquone, an ingredient in the antimalarial medication Malarone. Those parasites can reproduce in human or animal hosts, but the offspring have developmental defects and die in the mosquito portion of their life cycle, Christopher D. Goodman of the University of Melbourne and colleagues discovered.

The researchers tried to transmit a drug-resistant form of malaria to mice 44 times, involving 750 mosquito bites. Only one attempt succeeded, and that parasite couldn’t spread further even after seven attempts, Goodman and colleagues found.

Cytochrome b is needed for energy generation by mitochondria. Because mitochondria are inherited from the mother, even breeding with parasites that don’t have cytochrome b mutations won’t help the parasite escape its fate. The findings suggest that other antimalarial medications that target maternally inherited organelles in the parasite may also have limited drug resistance.