Phylogenetic Studies on ITS2, 5. 8S and 28S RRNA Genes in Dengue Virus Vector Mosquito Variants

Dengue is a remerging disease in the neotropical and is transmitted primarily by Aedes aegypti. The Asian tiger mosquito, A. albipictus, originally of sylvatic origin as well has spread widely since 1970s. Aedes mosquito species have been described from a wide range of environment and are involved in pathogen transmission from human to reservoir and vice versa. The survival of Aedes mosquito in varied geographical area suggests that it may evolve and adapt to these environments. This led to a study on ITS2, 5.8S and 28S RRNA sequence to find out the possible genetic variation among the selected variants of Dengue virus mosquitoes. The result suggests that the common motifs prove that all the variants of Aedes aegypti have a common ancestor different from Aedes albopictus. The status of Aedes cretinus as a separate species is questionable from the motifs study. In fact it is more closely related to Aedes albopictus variant I and II. The result was substantiated from RNA secondary structure prediction, phylogenetic analysis and estimates of evolutionary divergence between sequences among the variants. It is observed that species displaying sequence similarity belongs to different variants. The result also implies that the ITS2 and 28S RRNA sequence regions have less selective pressure than the ribosomal regions.