Dengue/Chikungunya Group, ICMR-National Institute of Virology, Pune 411001, India.
Dengue/Chikungunya Group, ICMR-National Institute of Virology, Pune 411001, India.
Infect Genet Evol. 2018 Dec;66:272-283. doi: 10.1016/j.meegid.2018.10.016. Epub 2018 Oct 23.
India witnessed dengue outbreaks during 2017 in different parts with more than 180000 cases. There is no data on the serotypes/genotypes of dengue virus (DENV) associated with the 2017 outbreak season. The present study investigated DENV circulating in Pune and Nashik regions of Maharashtra, Western India at molecular level. IgM negative samples that were collected before 6 post onset days of illness were tested for DENV RNA and serotyped by real time RT-PCR based methods. Representative samples of each serotype were processed for virus isolation and envelope (E) gene sequencing. Among the 472 samples tested for DENV serotypes from Nashik, DENV-1 was observed in 36.2%, DENV-2 in 12.9%, DENV-3 in 35.4%, DENV-4 in 8.0%, and multiple serotypes in 7.4% of the samples respectively. In Pune region, among the 109 samples tested for DENV serotypes, DENV-1 was observed in 27.5%, DENV-2 in 11.0%, DENV-3 in 52.3%, DENV-4 in 4.6%, and multiple serotypes in 4.6% of the samples respectively. Comparison of serotype distribution from 2009 to 2017 from the Pune region revealed the emergence of DENV-3 as the dominant serotype followed by DENV-1 in 2017. In the Nashik region, both DENV-1 and DENV-3 were predominant in 2017. Phylogenetic analyses revealed co-circulation of American African (AM/AF) and Asian genotypes of DENV-1. DENV-1 Asian genotype was detected for the first time in the region. No genotype changes were observed for DENV-2 (cosmopolitan genotype), DENV-3 (genotype III) and DENV-4 (genotype I). For DENV-3, a unique amino acid substitution (I380T) was observed in the domain III of E protein of 2017 isolates and was not observed in earlier DENV-3 genotype III isolates. To conclude, the results suggest the emergence of DENV-1 with circulation of both Asian and AM/AF genotypes and DENV-3 with unique amino acid substitutions in Pune and Nashik regions. The study underscores the need for continuous molecular monitoring at a large scale to detect the changes in DENV serotypes/genotypes that might have implications for earlier prediction of dengue outbreaks and designing dengue vaccines and predicting its efficacy.
印度在 2017 年不同地区爆发了登革热疫情，病例超过 18 万例。目前还没有关于与 2017 年爆发季节相关的登革热病毒（DENV）血清型/基因型的数据。本研究在分子水平上调查了印度西部马哈拉施特拉邦浦那和纳西克地区流行的 DENV。在发病后 6 天内采集的 IgM 阴性样本用于检测 DENV RNA，并通过实时 RT-PCR 方法进行血清分型。对每种血清型的代表性样本进行病毒分离和包膜（E）基因测序。在对来自纳西克的 472 份 DENV 血清型样本进行检测后，DENV-1 分别在 36.2%、DENV-2 在 12.9%、DENV-3 在 35.4%、DENV-4 在 8.0%和 7.4%的样本中观察到多种血清型。在浦那地区，对 109 份 DENV 血清型样本进行检测后，DENV-1 分别在 27.5%、DENV-2 在 11.0%、DENV-3 在 52.3%、DENV-4 在 4.6%和 4.6%的样本中观察到多种血清型。对 2009 年至 2017 年来自浦那地区的血清型分布进行比较后发现，DENV-3 已成为优势血清型，其次是 2017 年的 DENV-1。在纳西克地区，2017 年 DENV-1 和 DENV-3 均占优势。系统进化分析显示，DENV-1 同时存在美洲非非洲（AM/AF）和亚洲基因型。DENV-1 亚洲基因型首次在该地区被检测到。DENV-2（世界性基因型）、DENV-3（基因型 III）和 DENV-4（基因型 I）没有基因型变化。对于 DENV-3，在 2017 年分离株的 E 蛋白结构域 III 中观察到一个独特的氨基酸取代（I380T），而在早期的 DENV-3 基因型 III 分离株中未观察到该取代。总之，结果表明，在浦那和纳西克地区，DENV-1 出现了与亚洲和 AM/AF 基因型同时流行的情况，DENV-3 出现了独特的氨基酸取代。该研究强调需要在大规模范围内进行持续的分子监测，以检测 DENV 血清型/基因型的变化，这可能对早期预测登革热疫情、设计登革热疫苗和预测其疗效具有重要意义。
