Contrasting patterns of <i>Asaia</i> association with <i>Plasmodium falciparum</i> between field-collected <i>Anopheles gambiae</i> and <i>Anopheles coluzzii</i> from Cameroon

Abstract

The widespread prevalence of <i>Asaia</i> in mosquitoes makes it a potential candidate for paratrangenic control in <i>Anopheles</i>. To better understand whether this bacterium could be used for malaria control, we quantified <i>Asaia</i> in <i>An. gambiae s.l</i> populations in malaria endemic regions examining co-infection with <i>Plasmodium falciparum</i>. Adult <i>Anopheles</i> mosquitoes were collected across two different eco-geographical localities in Cameroon, during both the dry and wet seasons. DNA was extracted from whole individual mosquitoes, and real time-qPCR amplification of the <i>16S ribosomal</i> RNA was used to quantify <i>Asaia</i> in both <i>An. gambiae</i> and <i>An. coluzzii</i> samples. We also detected and quantified <i>P. falciparum</i> infection in the same mosquitoes. The density of <i>Asaia</i> was successfully quantified in a total of 864 field mosquitoes, comprising of 439 <i>An. gambiae</i> from Bankeng and 424 <i>An. coluzii</i> collected from Gounougou. Interestingly, a higher prevalence of <i>Asaia</i> in <i>An. gambiae</i> (88.3%) compared to <i>An. coluzzii</i> (80.9%) was observed. Moreover, the density of <i>Asaia</i> in both species was significantly affected by seasonal changes in the two localities. Furthermore, a significant difference between the infection densities of <i>Asaia</i> and the <i>Plasmodium</i> infection status in the two species was recorded. However, no correlation was observed between the number of <i>Asaia</i> and <i>P. falciparum</i> infections. This study provides evidence that naturally occurring <i>Asaia</i> infection is not correlated to <i>P. falciparum</i> development within <i>An. gambiae</i> and <i>An. coluzzii</i>. Nevertheless, further studies incorporating experimental infections are required to better investigate the correlation between <i>Anopheles</i> mosquitoes, <i>Asaia,</i> and <i>Plasmodium</i>.IMPORTANCEThe symbiont <i>Asaia</i> has emerged as a promising candidate for paratransgenic control of malaria, but further analysis of its biology and genetics across Africa is necessary. In this study, we investigated and quantified the influence of <i>Asaia</i> in naturally infected <i>An. gambiae s.l</i>. populations with the malaria parasite <i>Plasmodium falciparum</i>. Genomic DNA was extracted from whole individual mosquitoes collected from two localities, and <i>Asaia</i> was quantified using real-time qPCR by amplification of the 16S ribosomal RNA gene. We also detected and quantified <i>Plasmodium falciparum</i> infection in the same mosquitoes and established the correlation between <i>Asaia</i> and <i>Plasmodium</i> coinfection. This study provides evidence that naturally occurring <i>Asaia</i> infection is not correlated with <i>P. falciparum</i> development within <i>An. gambiae</i> and <i>An. coluzzii</i> mosquitoes.