Continued Circulation of DENV-2 (Genotype IV) in Delhi, India

Background: Dengue is one of the rapidly emerging arboviral infection in many parts of the world including India. The metropolitan city, Delhi is one of the worst affected areas by dengue. In the last two decades, it has witnessed frequent outbreaks with the continuous changing trend of circulating serotype(s)/genotype(s). The genetic characterization of circulating serotype(s)/genotype(s) is essential to establish the molecular epidemiology of the virus.

Aims: The present study was undertaken to elucidate the molecular epidemiology of dengue virus (DENV), circulated during the post-monsoon period of 2014.

Study Design: Total 112, dengue suspected samples were included in the study. Samples, positive in the NS1 antigen detection assay were processed for reverse transcription polymerase chain reaction (RT-PCR) and partial nucleotide sequencing for capsid-premembrane (CprM) gene region.

Results: Serotypic and genotypic analysis revealed cases of DENV-2 (genotype IV) 58.33%, DENV-3 (genotype III) 33.33% and DENV-1 (genotype III) 8.33%. Presence of DENV-2 (genotype IV) in majority of the cases (58.33%) indicated its pre-dominance. Multiple sequence alignment and phylogenetic analysis revealed the presence of a new strain of DENV-2 (genotype IV); differentiated from pre-existing strain by the substitutions; Ala102Val in capsid and Ile49Val in premembrane protein.

Conclusion: This study reports, continued circulation of DENV-2 (genotype IV) in 2014. The results also indicated circulation of a new strain of DENV-2, similar to Hyderabad isolate “1392” (JX475906), along with the pre-existing strain. It is proposed that, this strain has been introduced recently and circulating at low key in the capital.