Aw-Yong K L, Sam I C, Koh M T, Chan Y F
Department of Medical Microbiology, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Department of Paediatrics, Faculty of Medicine, University of Malaya, 50603 Kuala Lumpur, Malaysia.
Trop Biomed. 2017 Mar 1;34(1):240-248.
Hand, foot and mouth disease (HFMD) is a childhood illness, commonly caused by enterovirus A71 (EV-A71) and coxsackievirus A16 (CV-A16). In recent years, unusual HFMD outbreaks caused by coxsackievirus A6 (CV-A6) have been reported. From May 2012 to September 2013, enteroviruses were detected in 25 HFMD patients in University Malaya Medical Centre, Kuala Lumpur, Malaysia. The predominant serotypes were EV-A71 (48%) and CV-A6 (48%), followed by CV-A16 (4%). CV-A6 patients (mean age, 2.1) were significantly younger than EV-A71 patients (mean age, 3.3). There were no significant differences observed in clinical features between EV-A71 and CV-A6 patients. Since enteroviruses are difficult to differentiate clinically, the conserved 5' untranslated region (5' UTR) was used to identify enterovirus serotypes. Phylogenetic analysis of 5' UTR showed distinct clustering of viruses as EV-A71, CV-A16 and CV-A6. Further genotyping with capsid genes showed that all the EVA71 sequences belonged to subgenotype B5, while the CV-A16 sequence belonged to subgenotype B2b. CV-A6 sequences were clustered into genotypes D1 and D2, with recent isolates from Seri Kembangan, Malaysia and China. In summary, 59.5% of HFMD cases in our centre in 2012-2013 were caused by EV-A71, CV-A16 and the newly emerging CV-A6. This study also demonstrated that 5' UTR is suitable for preliminary identification of enteroviruses during HFMD outbreaks, but specific capsid genes such as VP1 and VP4/VP2 are required for further genotyping. Apart from measures to control the spread of the virus during an outbreak of HFMD, identification of EV-A71 as the etiological agent is important as EV-A71 is a major cause of severe neurological complications and potentially fatal.
手足口病（HFMD）是一种儿童疾病，通常由肠道病毒A71型（EV - A71）和柯萨奇病毒A16型（CV - A16）引起。近年来，已有由柯萨奇病毒A6型（CV - A6）引起的异常手足口病暴发的报道。2012年5月至2013年9月，在马来西亚吉隆坡马来亚大学医学中心的25例手足口病患者中检测到肠道病毒。主要血清型为EV - A71（48%）和CV - A6（48%），其次是CV - A16（4%）。CV - A6患者（平均年龄2.1岁）比EV - A71患者（平均年龄3.3岁）明显年轻。EV - A71和CV - A6患者的临床特征未观察到显著差异。由于肠道病毒在临床上难以区分，因此利用保守的5'非翻译区（5'UTR）来鉴定肠道病毒血清型。对5'UTR的系统发育分析显示病毒明显聚类为EV - A71、CV - A16和CV - A6。用衣壳基因进一步基因分型表明，所有EV - A71序列均属于B5亚型，而CV - A16序列属于B2b亚型。CV - A6序列聚类为D1和D2基因型，包括来自马来西亚斯里肯邦安和中国的近期分离株。总之，2012 - 2013年我们中心59.5% 的手足口病病例由EV - A71、CV - A16和新出现的CV - A6引起。本研究还表明，5'UTR适用于手足口病暴发期间肠道病毒的初步鉴定，但进一步基因分型需要如VP1和VP4/VP2等特定衣壳基因。除了在手足口病暴发期间采取控制病毒传播的措施外，鉴定EV - A71作为病原体很重要，因为EV - A71是严重神经并发症和潜在致命情况的主要原因。
