Two avianPlasmodiumspecies trigger different transcriptional responses on their vectorCulex pipiens

Abstract

AbstractMalaria is a mosquito-borne disease caused by protozoans of the genusPlasmodiumthat affects both humans and wildlife. The fitness consequences of infections by avian malaria are well known in birds, however, little information exists on its impact on mosquitoes. Here we study howCulex pipiensmosquitoes transcriptionally respond to infection by two differentPlasmodiumspecies,P. relictumandP. cathemerium, differing in their virulence (mortality rate) and transmissibility (parasite presence in exposed mosquitoes’ saliva). We study the mosquito response to the infection at three critical stages of parasite development: formation of ookinetes at 24 hours post-infection (hpi), the release of sporozoites into the hemocoel at 10 days post-infection (dpi), and storage of sporozoites in the salivary glands at 21dpi. For each time point, we characterized the gene expression of mosquitoes infected with eachP. relictumandP. cathemeriumand mosquitoes fed on an uninfected bird and, subsequently, compared their transcriptomic responses. Differential gene expression analysis showed most of the transcriptomic changes occurred during the early infection stage (24 hpi), especially when comparingP. relictumandP. cathemeriuminfected mosquitoes. Differentially expressed genes in mosquitoes infected with each species were related mainly to the immune response, trypsin, and other serine-proteases metabolism. We conclude that these differences in response may partly play a role in the differential virulence and transmissibility previously observed inP. relictumandP. cathemeriuminCx. pipiens.