Assessment of genetic diversity patterns of different serotypes of dengue virus, prevalent in patients from Kerala, India: a strain specific mutation study and its relevance to pathogenesis

The mutations are the key mechanisms responsible for virus survival and its fitness in the host. This process of mutation is implicated in the development of pathogenesis of the dengue viral disease. We report that, all the four serotypes were found to be circulating in Kerala sate of India. Serotypes 1 and 3 were the predominant type (33.3 %) compared to others. The prevalence of co-infection of serotype 1 and 4 was the highest percentage (11.1 %) compared to serotype 2 and serotype 3 (5.5 %). We further highlighted the immunopathological mechanisms of antibody neutralization, CD4+ T cell response and antibody dependent enhancements (ADE) for the possible cause of disease severity in coinfections. Serotype-1 does not show much variations from the previously reported strains from various regions of India. However, serotype-2 showed variations in the sequences from the other strains of serotype-2 previously reported from various regions of India and formed a distinct clade in the genotype-4. Serotype-3 and serotype-4 showed similarity with previously reported strains from India. Moreover, serotype-1 was grouping in genotype-5. Importantly, the serotype-2 grouped with genoptype-4 but exist separately. Serotype-3 was found to be grouped with the genotype-3. The serotype-4 show the very much similarities from the genotype-1 and shows little difference from the previously reported strains from India. Further, mutation in DENV-3 sequences, at position 235 (C to T) and 322 (G to T) shows an important phenomenon which might be adopted by the virus to survive. As severe dengue is linked with the serotype-2, the genetic variations in this serotype points towards the much specific strategy to be adopted in near future to manage the severe dengue disease. In conclusion, we can say that, genetic diversity in the CprM region is present in the different serotypes circulating in the patients from Kerala India and this information may help in the management of dengue viral disease.