Contrasting patterns of Asaia sp association with Plasmodium falciparum between field collected Anopheles gambiae and Anopheles coluzzii from Cameroon

Abstract

The presence of bacteria of the genus Asaia in mosquitoes makes them suitable candidates for malaria paratrangenic control. To better understand whether this bacterium could be used for malaria control, we investigated and quantified Asaia influence in An.Lgambiae sl populations naturally infected by the malaria parasite Plasmodium falciparum. Adult Anopheles mosquitoes were collected across two different eco-geographical localities in Cameroon, during the dry and wet seasons. DNA was extracted from the whole individual mosquitoes and Asaia was quantified using real-time Q-PCR by amplification of 16S ribosomal RNA gene. We also detected and quantified Plasmodium falciparum infection in same mosquitoes. The density of Asaia was quantified in 864 mosquitoes. This included 439 An. gambiae collected from Bankeng and 425 An. coluzzii collected from Gounougou. The prevalence of Asaia in An. gambiae and An. coluzzii was 88.3% and 80.9% respectively, with An. gambiae were more heavily infected by Asaia than An. coluzzii. There was also a significant difference between the infection densities of Asaia per season in the two localities. We also had a significant difference between the infection densities of Asaia according to Plasmodium infection status in the two localities. However, no correlation was observed between the amount of Asaia and P. falciparum infection. This study provides evidence that naturally occurring Asaia infection is not correlated to P. falciparum development within An. gambiae and An. coluzzii. Further studies as experimental infection and innate immune response are required to better investigate the correlation between Anopheles mosquitoes, Asaia and Plasmodium. ImportanceMalaria control relies mainly on insecticide-based tools. However, the effectiveness of these tools is threatened by the widespread insecticide resistance in malaria vectors highlighting the need for alternative control approaches. The endosymbiont Asaia has emerged as a promising candidate for paratransgenic control of malaria, but its biology and genetics still need to be further analyzed across Africa. Here, we investigated and quantified Asaia influence in An.Lgambiae sl populations naturally infected by the malaria parasite Plasmodium falciparum. DNA was extracted from the whole individual mosquitoes collected from two localities, and then Asaia was quantified using real-time Q-PCR by amplification of 16S ribosomal RNA gene. We also detected and quantified Plasmodium falciparum infection in same mosquitoes and correlated Plasmodium infection them with the presence of Asaia infection. This study provides evidence that naturally occurring Asaia infection is not correlated to P. falciparum development within An. gambiae and An. coluzzii.