<p>First Full-Length Genome Sequence of Dengue Virus Serotype 2 Circulating in Vietnam in 2017</p>

Abstract

Introduction Dengue hemorrhagic fever is caused by four serotypes of dengue viruses transmitted by mosquitoes. In Vietnam, dengue outbreaks occur every year, and all four serotypes have been found circulating with the dominant one varying over time. However, in 2017 an unusual dengue fever outbreak occurred in the North of Vietnam, predominantly caused by DENV1 (92%) and DENV2 (7.3%). The objective of the present study was to obtain and characterize the full-length genome sequence of seven DENV2 strains in 2017 epidemic. Materials and Methods Whole-genome sequencing of seven DENV2 isolates from the 2017 outbreak were obtained using the Illumina MiSeq next generation sequencer system. Complete genome sequences were then analyzed to find out genetic variants and genetic relationships between these DENV2 with other strains that circulated in Vietnam previously and other regions of the world. Results The complete genome sequence of seven DENV2 isolates in the 2017 dengue outbreak comprised 10,696 nucleotides with an open reading frame coding for 3392 amino acids. The genome analysis showed only a small number of amino acid changes which were obtained in all genes, in which a few amino acids substitutions were distributed over the positions such as G156 (NS1), V106 (NS2A), and L258/T260 (NS5). The phylogenetic analysis revealed that the DENV2 isolates in the 2017 outbreak were most closely related to the dengue virus from India in 2006, suggesting that the causative virus originated from the DENV2 that caused dengue hemorrhagic fever in 2006 in India. Conclusion The first complete genome sequences of seven DENV2 isolates in the 2017 dengue outbreak in Northern Vietnam were successfully obtained. The genetic and phylogenetic data indicated that these DENV2 isolates were not causative virus circulating in Vietnam previously but originated from India in 2006. These data are emerging and providing valuable information for the management and surveillance of dengue in Vietnam.

An Outbreak of Dengue Virus Serotype 2 Cosmopolitan Genotype in Nepal, 2017

“…These results also showed that different DENV strains found in Nepal were imported from different geographical areas before there was local transmission. Similar to the present study, DENV strains were imported from different geographical areas in studies reported in China, Singapore, and Vietnam [ 44 ]. The diversity of DENV-2 strains has been shown to play an important role in the resurgence of severe dengue infection [ 45 ].…”

Dengue: A review of laboratory diagnostics in the vaccine age

“…Additionally, viral mutation may have implications for specificity of NAAT test targets. These may be of relevance for epidemiologic investigations and public health interventions, including immunization [135]. Sequencing could also be used to confirm a diagnosis if false positives in NAAT were suspected.…”

“…Genotypes have been defined by Sanger sequencing of the E gene [134]. Multiple genotypes are recognized within a serotype [135]. With the advent of next generation sequencing (NGS) high-throughput methodologies, a more detailed understanding of viral adaptation and mutation through sequence variation, as well as phylogeny relating to local epidemiology can be appreciated through whole-genome comparison [136].…”

Analysis of pathogenic genes in dengue virus

“…This polyprotein, composed of a linear sequence of amino acids, undergoes cleavage by both viral and host proteases to yield individual proteins crucial for various stages of the viral life cycle. The key constituents of the genomic structure of Dengue virus include (Dang et al, 2020) [2] .…”