Diarrhoeal Pathogens Research Unit, Department of Virology, WHO AFRO Rotavirus Regional Reference Laboratory, Sefako Makgatho Health Sciences University, Pretoria, South Africa.
Next Generation Sequencing Unit and Department of Medical Microbiology and Virology, Faculty of Health Sciences, University of the Free State, Bloemfontein, South Africa.
BMC Infect Dis. 2021 Jan 22;21(1):107. doi: 10.1186/s12879-020-05745-6.
G12 rotaviruses were first observed in sub-Saharan Africa in 2004 and since then have continued to emerge and spread across the continent and are reported as a significant human rotavirus genotype in several African countries, both prior to and after rotavirus vaccine introduction. This study investigated the genetic variability of 15 G12 rotavirus strains associated with either P[6] or P[8] identified between 2010 and 2014 from Ethiopia, Kenya, Rwanda, Tanzania, Togo and Zambia.
The investigation was carried out by comparing partial VP7 and partial VP4 sequences of the African G12P[6] and G12P[8] strains with the available GenBank sequences and exploring the recognized neutralization epitopes of these strains. Additionally, Bayesian evolutionary analysis was carried out using Markov Chain Monte Carlo (MCMC) implemented in BEAST to estimate the time to the most recent ancestor and evolutionary rate for these G12 rotavirus strains.
The findings suggested that the VP7 and VP4 nucleotide and amino acid sequences of the G12 strains circulating in African countries are closely related, irrespective of country of origin and year of detection, with the exception of the Ethiopian strains that clustered distinctly. Neutralization epitope analysis revealed that rotavirus VP4 P[8] genes associated with G12 had amino acid sequences similar to those reported globally including the vaccine strains in RotaTeq and Rotarix. The estimated evolutionary rate of the G12 strains was 1.016 × 10 substitutions/site/year and was comparable to what has been previously reported. Three sub-clusters formed within the current circulating lineage III shows the diversification of G12 from three independent ancestries within a similar time frame in the late 1990s.
At present it appears to be unlikely that widespread vaccine use has driven the molecular evolution and sustainability of G12 strains in Africa. Continuous monitoring of rotavirus genotypes is recommended to assess the long-term impact of rotavirus vaccination on the dynamic nature of rotavirus evolution on the continent.
2004 年首次在撒哈拉以南非洲观察到 G12 轮状病毒，此后，该病毒继续在非洲大陆出现和传播，并在轮状病毒疫苗引入之前和之后被报告为几个非洲国家的重要人类轮状病毒基因型。本研究调查了 2010 年至 2014 年期间在埃塞俄比亚、肯尼亚、卢旺达、坦桑尼亚、多哥和赞比亚发现的与 P[6]或 P[8]相关的 15 株非洲 G12 轮状病毒株的遗传变异性。
通过将非洲 G12P[6]和 G12P[8]株的部分 VP7 和部分 VP4 序列与可用的 GenBank 序列进行比较，以及探索这些株的公认中和表位，对 G12 株进行了调查。此外，还使用贝叶斯进化分析（BEAST）通过马尔可夫链蒙特卡罗（MCMC）对这些 G12 轮状病毒株进行了时间到最近共同祖先和进化率的估计。
研究结果表明，无论起源国和检测年份如何，在非洲国家循环的 G12 株的 VP7 和 VP4 核苷酸和氨基酸序列都非常相似，除了埃塞俄比亚株明显聚类不同。中和表位分析表明，与 G12 相关的轮状病毒 VP4 P[8]基因具有与全球报告的类似的氨基酸序列，包括 RotaTeq 和 Rotarix 中的疫苗株。G12 株的估计进化率为 1.016×10 个替换/位点/年，与以前报道的相似。目前流行的谱系 III 内形成了三个亚群，表明 G12 在 20 世纪 90 年代末的相似时间内从三个独立的祖先中多样化。
目前看来，广泛使用疫苗不太可能推动 G12 株在非洲的分子进化和可持续性。建议继续监测轮状病毒基因型，以评估轮状病毒疫苗对非洲轮状病毒进化动态的长期影响。
