A population modification gene drive targeting both <i>Saglin</i> and <i>Lipophorin</i> impairs <i>Plasmodium</i> transmission in <i>Anopheles</i> mosquitoes.

Abstract

Lipophorin is an essential, highly expressed lipid transport protein that is secreted and circulates in insect hemolymph. We hijacked the <i>Anopheles coluzzii Lipophorin</i> gene to make it co-express a single-chain version of antibody 2A10, which binds sporozoites of the malaria parasite <i>Plasmodium falciparum</i>. The resulting transgenic mosquitoes show a markedly decreased ability to transmit <i>Plasmodium berghei</i> expressing the <i>P. falciparum</i> circumsporozoite protein to mice. To force the spread of this antimalarial transgene in a mosquito population, we designed and tested several CRISPR/Cas9-based gene drives. One of these is installed in, and disrupts, the pro-parasitic gene <i>Saglin</i> and also cleaves wild-type <i>Lipophorin,</i> causing the anti-malarial modified <i>Lipophorin</i> version to replace the wild type and hitch-hike together with the <i>Saglin</i> drive. Although generating drive-resistant alleles and showing instability in its gRNA-encoding multiplex array, the <i>Saglin</i>-based gene drive reached high levels in caged mosquito populations and efficiently promoted the simultaneous spread of the antimalarial <i>Lipophorin::Sc2A10</i> allele. This combination is expected to decrease parasite transmission via two different mechanisms. This work contributes to the design of novel strategies to spread antimalarial transgenes in mosquitoes, and illustrates some expected and unexpected outcomes encountered when establishing a population modification gene drive.