MDR1-associated resistance to artesunate + mefloquine does not impair blood-stage parasite fitness in a rodent malaria model

- Rodent malaria parasites (Plasmodium chabaudi) resistant to artesunate (ATN) + mefloquine (MF) were previously selected.
- ATN + MF-resistant parasites were shown to attain amplification of the mdr1 gene after the evolution of resistance.
- Here, the blood-stage fitness associated with artesunate + mefloquine (ATN + MF) resistance was investigated in vivo.
- There was no fitness cost linked to ATN + MF resistance, and consequently, to mdr1 amplification.
- The improved growth of the ATN + MF-resistant parasites may be due to selection of compensatory mutations.