Transcriptomic Analysis of Anopheles gambiae Immune Responses to Plasmodium falciparum Infection in Nigerian Field Populations

The outcome of Plasmodium falciparum infection in Anopheles gambiae mosquitoes is determined by the interplay between parasite virulence factors and vector immune gene expression, and characterising this interaction in field populations is essential for developing transmission-blocking strategies relevant to Nigeria. This doctoral study conducted a transcriptomic analysis of An. gambiae immune responses to P. falciparum infection using RNA sequencing. Field-collected An. gambiae from Oyo State, Southwest Nigeria, were fed on blood from P. falciparum-infected and uninfected volunteer donors under controlled membrane feeding conditions. At 7 and 14 days post-blood meal, midguts from infected and uninfected mosquitoes were dissected and total RNA extracted for Illumina-based RNA sequencing. Differential gene expression analysis used DESeq2. A total of 1,847 genes were differentially expressed in infected versus uninfected mosquitoes (|log2FC| greater than 1.5, FDR less than 0.05). Immune pathway genes including Rel2, TEP1, LRRD7, and components of the Imd and Toll pathways were significantly upregulated. Melanisation pathway genes were suppressed, consistent with parasite immune evasion. Nitric oxide synthase was among the most strongly upregulated anti-parasitic effectors. Transcriptomic signatures differed significantly between field-collected and colonised mosquito strains, validating the importance of field-based transcriptomics. These data provide the first An. gambiae-P. falciparum transcriptome profile from Nigerian field mosquitoes. Keywords: Anopheles gambiae, transcriptomics, immune response, Plasmodium falciparum, RNA sequencing.