Genetic and pathogenicity diversity of dengue virus type 2 strains circulating in Guangdong, China

•Scientific question Dengue diseases are presently the most important arboviral infections of humans. Phylogenetic analyses and pathogenicity of different dengue virus type 2 strains prevalent in Guangdong China have not been well addressed.•Evidence before this study DENV exists in four serotypes, including DENV-1 to DENV-4, each subdivided in genotype or subgenotypes. For the past decades, DENV-1 was predominantly prevalent in Guangdong province, DENV-2 was detected sporadically. Recently DENV-2 infection has increased significantly in 2018 compared with previous years, indicating a small-scale DENV-2 outbreak. Genetic and pathogenic analyses of DENV-2 are warranted to evaluate the risk of DENV-2 in human population.•New findings In this study, a total of 22 DENV-2 genomes were obtained by virus isolation and high-throughput sequencing. Phylogenetic, Bayesian MCMC and single amino polymorphism analyses were performed, indicated that two major subgenotypes (A and C) of DENV-2 Cosmopolitan were prevalent in Guangdong in 2018. Pathogenicity comparison between different DENV-2 subgenotypes in animal model was conducted. Subgenotype A of Cosmopolitan infected mice showed increased weight loss and delayed viral clearance compared with subgenotype C group.•Significant of the study DENV-2 strains prevalent in Guangdong in 2018 showed obvious genetic and pathogenicity diversity in vitro and in vivo, indicating the necessity of molecular surveillance. Our findings are informative for understanding the fitness in population of DENV-2 to changing conditions.