Department of Infectious Diseases, Guangzhou Center for Disease Control and Prevention, Guangzhou, Guangdong, People's Republic of China.
Department of Biostatistics and Epidemiology, School of Public Health, University of California, Berkeley, CA, USA.
Parasit Vectors. 2021 Feb 27;14(1):126. doi: 10.1186/s13071-021-04631-7.
Dengue fever is a mosquito-borne infectious disease that has caused major health problems. Variations in dengue virus (DENV) genes are important features of epidemic outbreaks. However, the associations of DENV genes with epidemic potential have not been extensively examined. Here, we assessed new genotype invasion of DENV-1 isolated from Guangzhou in China to evaluate associations with epidemic outbreaks.
METHODOLOGY/PRINCIPAL FINDINGS: We used DENV-1 strains isolated from sera of dengue cases from 2002 to 2016 in Guangzhou for complete genome sequencing. A neighbor-joining phylogenetic tree was constructed to elucidate the genotype characteristics and determine if new genotype invasion was correlated with major outbreaks. In our study, a new genotype invasion event was observed during each significant outbreak period in 2002-2003, 2006-2007, and 2013-2014. Genotype II was the main epidemic genotype in 2003 and before. Invasion of genotype I in 2006 caused an unusual outbreak with 765 cases (relative risk [RR] = 16.24, 95% confidence interval [CI] 12.41-21.25). At the middle and late stages of the 2013 outbreak, genotype III was introduced to Guangzhou as a new genotype invasion responsible for 37,340 cases with RR 541.73 (95% CI 417.78-702.45), after which genotypes I and III began co-circulating. Base mutations occurred after new genotype invasion, and the gene sequence of NS3 protein had the lowest average similarity ratio (99.82%), followed by the gene sequence of E protein (99.86%), as compared to the 2013 strain.
CONCLUSIONS/SIGNIFICANCE: Genotype replacement and co-circulation of multiple DENV-1 genotypes were observed. New genotype invasion was highly correlated with local unusual outbreaks. In addition to DENV-1 genotype I in the unprecedented outbreak in 2014, new genotype invasion by DENV-1 genotype III occurred in Guangzhou.
登革热是一种由蚊子传播的传染病，已造成重大健康问题。登革病毒（DENV）基因的变异是疫情爆发的重要特征。然而，DENV 基因与流行潜力的关联尚未得到广泛研究。在这里，我们评估了从中国广州分离的 DENV-1 的新基因型入侵，以评估与疫情爆发的关联。
方法/主要发现：我们使用从 2002 年至 2016 年广州登革热病例血清中分离的 DENV-1 株进行全基因组测序。构建了一个邻接聚类系统进化树，以阐明基因型特征，并确定新基因型入侵是否与重大疫情有关。在我们的研究中，在 2002-2003 年、2006-2007 年和 2013-2014 年的每个重大疫情期间都观察到了新基因型的入侵事件。基因型 II 是 2003 年及以前的主要流行基因型。2006 年基因型 I 的入侵导致了一起异常疫情，共 765 例病例（相对风险 [RR] = 16.24，95%置信区间 [CI] 12.41-21.25）。在 2013 年疫情的中后期，基因型 III 作为新的基因型入侵引入广州，导致 37340 例病例，RR 为 541.73（95%CI 417.78-702.45），之后基因型 I 和 III 开始共同传播。新基因型入侵后发生了碱基突变，NS3 蛋白基因序列的平均相似性比值最低（99.82%），其次是 E 蛋白基因序列（99.86%），与 2013 年的株相比。
结论/意义：观察到 DENV-1 基因型的替代和多种 DENV-1 基因型的共同循环。新基因型的入侵与当地不寻常的疫情高度相关。除了 2014 年空前的 DENV-1 基因型 I 疫情外，DENV-1 基因型 III 的新基因型入侵也发生在广州。
