Genetic characterization of dengue virus serotype 2 isolated from dengue fever outbreaks in eastern Uttar Pradesh and western Bihar, India

Dengue (DEN) is the most common cause of mosquito‐borne endemic viral diseases in the tropical and subtropical countries. DEN outbreaks associated with multiple dengue virus (DV) serotypes have been regularly reported in different parts of India. This study was done during DEN outbreaks in 2015 to 2016 in UP and Bihar where DEN‐2 was found as the only prevalent serotype. DV‐2 was the only serotype amplified in serotype‐specific reverse‐transcription polymerase chain reaction from sera of 210 (65.21%) out of 322 DV NS1 antigen‐positive patients. Further genetic analysis based on full‐length envelope (E) protein sequence derived from patient's sera as well as DV isolate showed the circulation of lineages I and III of DV‐2 cosmopolitan genotype during 2015 and lineage II during 2016. Finally, the phylogenetic analysis using the E gene sequence revealed that these DV‐2 strains have a close genetic relationship with the recently reported DV‐2 genotypes from DEN outbreaks reported from different parts of north India. These results showed the circulation of cosmopolitan genotype of DV‐2 in eastern Uttar Pradesh and western Bihar, India. The genetic database generated on circulating DV strains in this study will be useful as reference for disease surveillance and strengthening laboratory diagnosis protocols. Highlights In the study, we observed that DV‐2 Cosmopolitan is the major genotype associated with the dengue outbreak during 2015 and 2016 in eastern Uttar Pradesh and Western Bihar of India. Further, we also observed that shift in lineage of DV‐2 Cosmopolitan genotype from I and III during 2015 to lineage II during 2016.