Molecular characterization and genotype distribution of thioester-containing protein 1 gene in Anopheles gambiae mosquitoes in western Kenya

• Published in: Malaria Journal
• Main Authors: Shirley A. Onyango, Kevin O. Ochwedo, Maxwell G. Machani, Julius O. Olumeh, Isaiah Debrah, Collince J. Omondi, Sidney O. Ogolla, Ming-Chieh Lee, Guofa Zhou, Elizabeth Kokwaro, James W. Kazura, Yaw A. Afrane, Andrew K. Githeko, Daibin Zhong, Guiyun Yan
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2022
• Subjects: Anopheles gambiae; Thioester-containing protein 1; Genetic diversity; Population structure; Signature of selection; Malaria transmission; Arctic medicine. Tropical medicine; RC955-962; Infectious and parasitic diseases; RC109-216; Arctic
• Online Access: https://doi.org/10.1186/s12936-022-04256-w; https://doaj.org/article/bd9e792b4298405ebe3a4428400020b2

Abstract Background Evolutionary pressures lead to the selection of efficient malaria vectors either resistant or susceptible to Plasmodium parasites. These forces may favour the introduction of species genotypes that adapt to new breeding habitats, potentially having an impact on malaria transmission. Thioester-containing protein 1 (TEP1) of Anopheles gambiae complex plays an important role in innate immune defenses against parasites. This study aims to characterize the distribution pattern of TEP1 polymorphisms among populations of An. gambiae sensu lato (s.l.) in western Kenya. Methods Anopheles gambiae adult and larvae were collected using pyrethrum spray catches (PSC) and plastic dippers respectively from Homa Bay, Kakamega, Bungoma, and Kisumu counties between 2017 and 2020. Collected adults and larvae reared to the adult stage were morphologically identified and then identified to sibling species by PCR. TEP1 alleles were determined in 627 anopheles mosquitoes using restriction fragment length polymorphisms-polymerase chain reaction (RFLP-PCR) and to validate the TEP1 genotyping results, a representative sample of the alleles was sequenced. Results Two TEP1 alleles (TEP1*S1 and TEP1*R2) and three corresponding genotypes (*S1/S1, *R2/S1, and *R2/R2) were identified. TEP1*S1 and TEP1*R2 with their corresponding genotypes, homozygous *S1/S1 and heterozygous *R2/S1 were widely distributed across all sites with allele frequencies of approximately 80% and 20%, respectively both in Anopheles gambiae and Anopheles arabiensis. There was no significant difference detected among the populations and between the two mosquito species in TEP1 allele frequency and genotype frequency. The overall low levels in population structure (F ST = 0.019) across all sites corresponded to an effective migration index (Nm = 12.571) and low Nei’s genetic distance values (< 0.500) among the subpopulation. The comparative fixation index values revealed minimal genetic differentiation between species and high levels of gene flow among ...