Toward field-ready paratransgenesis for malaria: bacterial strain optimization and microbiota interactions - PROJECT SUMMARY/ABSTRACT Malaria is a disease caused by protozoan parasites (Plasmodium spp.) that are transmitted to humans by female mosquitoes of the genus Anopheles. There are nearly 250 million new cases of malaria every year, and over 600,000 people die from the disease while millions of others are severely debilitated (data from 2021). About half of the human population is at risk of contracting malaria, and its range may spread as global warming accelerates. A long-term research goal of high priority in the biomedical health sciences therefore is to create new methods of combating malaria to complement current methods of control, namely insecticides to kill mosquito vectors and drugs to kill parasites in infected people. The overall objective of this multi-PI proposal is to engineer paratransgenic bacterial strains that can interfere with the ability of mosquitoes to transmit malaria parasites. We will accomplish this by leveraging our combined expertise in bacterial genetics and vector microbial ecology to overcome existing challenges that make currently available paratransgenic strains unsuitable for field release. More specifically, we will engineer paratransgenic strains of Asaia bogorensis that contain no antibiotic resistance genes, that are highly resistant against horizontal transfer to non-target species, and that secrete combinations of effector proteins at sufficient quantities for optimal anti-Plasmodium performance in vivo (Aim 1). We will also concurrently examine the impact of microbiota composition and paratransgenesis system components on the overall fitness and anti-Plasmodium performance of paratransgenic strains in mosquitoes colonized by bacterial communities derived from individuals collected in malaria endemic regions of West Africa (Aim 2). Together, these experiments will allow us to identify field-ready strains that are likely to persist after introduction into natural mosquito populations, with little to no impact on resident microbial communities and minimal need for costly reintroduction strategies. They will also significantly advance our fundamental understanding of how individual bacterial strains colonize and persist in mosquito hosts–a topic of broad interest given the ability of mosquito-associated bacteria to shape mosquito phenotypes important for pathogen transmission.
