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.

Co-circulation of all the four Dengue virus serotypes during 2018-2019: first report from Eastern Uttar Pradesh, India.

Dengue fever is an endemic disease in India, transmitted by an infected mosquito bite. In India, the number of concurrent infections and the circulation of multiple dengue virus (DENV) serotypes has increased in recent decades. Molecular surveillance among the DENV serotype is important to keep track of the circulating serotypes, evolutionary changes, and key mutations that can alter the diagnostics. The current study included patients admitted for dengue in the Eastern Uttar Pradesh (E-UP) region during 2018-2019. The genetic characterization of the circulating DENV was accomplished through partial CprM (511 bp) gene amplification via reverse transcriptase polymerase chain reaction and sequencing. Phylogenetic analysis revealed the circulation of all four DENV1-4 serotypes. DENV-2 was the most abundant serotype (44%, 27/61), followed by DENV-3 (32%, 20/61). DENV-1 had a 16% (10/61) predominance, while DENV-4 (6%, 4/61) was found to be the least abundant serotype. DENV-2 genotypes were distributed among lineages I (7.4%), II (85%) and III (7.4%) of genotype IV, DENV-3 to lineage III of genotype III, DENV-1 to genotype III; DENV-2 to lineage B (75%) and C (25%) of genotype I. This primary report on the co-circulation of DENV1-4 serotypes from the E-UP region highlights the requirement of continuous molecular surveillance for monitoring circulating DENV serotypes.