Molecular Epidemiology of Dengue Viruses Isolated in Shantou City, China, during 2015-2017

Dengue viruses (DENVs) affect tropical and subtropical regions, including the Guangdong province of China. Dengue cases are reported almost every year in Shantou city in the Guangdong province. To understand the molecular characteristics of DENVs isolated in Shantou, we performed a molecular epidemiological study based on the envelope protein (E) gene of the DENVs isolated from the cases. Total 174 serum samples were collected from 174 dengue-suspected patients during 2015-2017. A total of 33.9% (59/174) were diagnosed with dengue. Serotypes of DENVs were identified in 27 samples; 37% (10/27), 55.6% (15/27), 3.7% (1/27), 3.7% (1/27) were serotype 1 DENV (DENV-1), serotype 2 DENV (DENV-2), serotype 3 DENV (DENV-3), and serotype 4 DENV (DENV4), respectively. Genotypes Ⅰ and Ⅳ were detected in DENV-1, while only the Cosmopolitan genotype was detected in DENV-2. The replacement of the predominant serotype (genotype), which takes place every year, implied that the dengue endemic in Shantou might be caused by an imported infection rather than by local populations. Our results suggested that DENVs in Shantou are closely related to the strains circulating in Southeast Asian countries, which were possibly transmitted to Shantou through some relay point cities.