Chikungunya virus susceptibility & variation in populations of Aedes aegypti (Diptera: Culicidae) mosquito from India

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From: Indian Journal of Medical Research(Vol. 142, Issue 7)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Report
Length: 5,320 words
Lexile Measure: 1390L

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Byline: Mangesh. Gokhale, Mandar. Paingankar, Anakathil. Sudeep, Deepti. Parashar

Background & objectives: Although having immense clinical relevance, yet only a few studies have been targeted to understand the chikungunya virus (CHIKV) susceptibility and growth in Aedes aegypti populations from India. This study was undertaken to investigate CHIKV susceptibility and growth kinetics in Ae. aegypti along with genetic heterogeneity of Ae. aegypti populations. Methods: Dose dependent CHIKV susceptibility and growth kinetic studies for three CHIKV strains reported from India were carried out in Ae. aegypti mosquito populations. The phenotypic variation and genetic heterogeneity in five Ae. aegypti populations were investigated using multivariate morphometrics and allozyme variation studies. Results: The dissemination and growth kinetics studies of the three CHIKV strains showed no selective advantage for a particular strain of CHIKV in Ae. aegypti. At 100 per cent infection rate, five geographic Ae. aegypti populations showed differences in dissemination to three CHIKV strains. Morphometric studies revealed phenotypic variation in all the studied populations. The allelic frequencies, F statistics, and Nei's genetic identity values showed that genetic differences between the populations were small, but significant. Interpretation & conclusions: The results obtained in this study suggest that genetic background of the vector strongly influences the CHIKV susceptibility in Ae. aegypti.

Several environmental, physiological and genetic factors are known to govern the vector competence of mosquitoes [sup][1],[2], . Susceptibility to infection, permissiveness for pathogen development, duration of incubation period and transmission efficiency contribute to vector competence. To establish the successful infection in vector, virus has to overcome numerous barriers to infection and dissemination within the mosquito, many of which are under genetic control [sup][1],[2] . All these factors are known to influence the association between the vector, the pathogen transmitted by the vector and the vertebrate host into which the pathogen is transmitted [sup][1] .

Chikungunya virus (CHIKV) is endemic in Africa and Southeast Asia and is transmitted by Aedes mosquitoes through an urban or sylvatic transmission cycle [sup][3] . Three distinct CHIKV phylogenetic groups viz. one containing all the isolates from West Africa, one containing the isolates from Asia, and one corresponding to Eastern, Central and Southern African (ECSA) isolates, have been reported [sup][4],[5],[6],[7] . Avariant of CHIKV harbouring a substitution in the residue of the E1 glycoprotein (E1-226V) has been demonstrated to be efficiently transmitted by the Aedes albopictus [sup][8],[9] .

The susceptibility of Aedes mosquitoes to CHIKV infection varies widely among individual mosquitoes and between the mosquito populations [sup][10],[11],[12] . The genetic heterogeneity in the mosquito populations and in the virus strains might be crucial for differential susceptibility of vectors. Only a few in depth studies on CHIKV susceptibility and growth kinetics in Ae. aegypti and the genetic heterogeneity in Ae. aegypti mosquito populations have been reported in literature [sup][9],[11] . We, therefore, investigated the susceptibility, dissemination and growth kinetics of three CHIKV strains in Ae. aegypti and genetic variability in five different Ae. aegypti populations.

Material & Methods

The experiments were done in a biosafety level-2 animal facility at the National Institute...

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Gale Document Number: GALE|A444558626