Genetic deviation in geographically close populations of the dengue vector Aedes aegypti (Diptera: Culicidae): influence of environmental barriers in South India

Abstract

Mosquitoes are vectors of devastating pathogens and parasites, causing millions of deaths every year. Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. Recently, dengue transmission has strongly increased in urban and semiurban areas, becoming a major international public health concern. Aedes aegypti (Diptera: Culicidae) is a primary vector of dengue. Shedding light on genetic deviation in A. aegypti populations is of crucial importance to fully understand their molecular ecology and evolution. In this research, haplotype and genetic analyses were conducted using individuals of A. aegypti from 31 localities in the north, southeast, northeast and central regions of Tamil Nadu (South India). The mitochondrial DNA region of cytochrome c oxidase 1 (CO1) gene was used as marker for the analyses. Thirty-one haplotypes sequences were submitted to GenBank and authenticated. The complete haplotype set included 64 haplotypes from various geographical regions clustered into three groups (lineages) separated by three fixed mutational steps, suggesting that the South Indian Ae. aegypti populations were pooled and are linked with West Africa, Columbian and Southeast Asian lineages. The genetic and haplotype diversity was low, indicating reduced gene flow among close populations of the vector, due to geographical barriers such as water bodies. Lastly, the negative values for neutrality tests indicated a bottle-neck effect and supported for low frequency of polymorphism among the haplotypes. Overall, our results add basic knowledge to molecular ecology of the dengue vector A. aegypti, providing the first evidence for multiple introductions of Ae. aegypti populations from Columbia and West Africa in South India.

Distribution and pyrethroid resistance status of Aedes aegypti and Aedes albopictus populations and possible phylogenetic reasons for the recent invasion of Aedes aegypti in Nepal

“…Tajima's D was calculated using DnaSP based on 576 bp sequences with missing sites excluded. To construct the haplotype network, cox1 sequences from around the world were obtained from previous studies [18][19][20][21][22][23][24][25][26][27][28][29][30] and GenBank (Additional file 1: Table S1). The haplotype network was constructed using TCS v.1.21 [30] based on data from Nepal, Myanmar and other global haplotypes measuring 589-593 bp.…”

Mitochondrial metabolic genes provide phylogeographic relationships of global collections of Aedes aegypti (Diptera: Culicidae)

“…The two origins are, one from India/Pakistan and another from mixed clades of mosquitoes derived from East Africa. This appears to be counter intuitive based upon the proximity of Sri Lanka to India and its great distance to East Africa and the fact that most of the India collections come from South India [42]. The analysis of migration rates in Table 3 supports the idea that while there is a great deal of gene flow, among mosquitoes within the India/Pakistan Region there is very little gene flow between India/Pakistan and Africa or Sri Lanka.…”

“…However, an independent molecular clock has been estimated for CO1 [48] and at least seven large datasets for CO1 in Ae. aegypti have appeared [7,21,[39][40][41][42][43]. Some of the problems associated with studies of the mitochondrial genome in Ae.…”

“…GenBank contains 546 Ae. aegypti CO1 sequences and 363 of these contain the same 460 bp region of CO1 as in the current study [39][40][41][42][43]. Sequences from laboratory strains were excluded.…”

Genetic analysis ofAedes aegypticaptured in two international airports serving to the Greater Tokyo Area during 2012—2015

“…aegypti, and hits with more than 95% query coverage were aligned using MUSCLE (22). Sequences retrieved were AF380835, AF390098 and AY056597 (23); AF425846 (24); AY432106 and AY432648 (25); EU352212; HQ688292-688298 (26), JQ926676-926684, JQ926686-926690, JQ926692-926696, JQ926698-926700 and JQ926702, JQ926704 (27); KF909122 (28), KM203140-203248 (29); KT313642, KT313645, KT313648, KT313650-313653 (30); KT339661 and KT339679-339683 (31), KU186990; KX171382-171394. Haplotype network was drawn for the alignment using the pegas package (v0.11) in R (32).…”