Centre for Bioinformatics, School of Data Sciences, Perdana University, Wisma Chase Perdana, Changkat Semantan, Damansara Heights, Kuala Lumpur 50490, Malaysia.
Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205, USA.
Viruses. 2021 May 10;13(5):871. doi: 10.3390/v13050871.
Avian influenza virus A (H7N9), after circulating in avian hosts for decades, was identified as a human pathogen in 2013. Herein, amino acid substitutions possibly essential for human adaptation were identified by comparing the 4706 aligned overlapping nonamer position sequences (1-9, 2-10, etc.) of the reported 2014 and 2017 avian and human H7N9 datasets. The initial set of virus sequences (as of year 2014) exhibited a total of 109 avian-to-human (A2H) signature amino acid substitutions. Each represented the most prevalent substitution at a given avian virus nonamer position that was selectively adapted as the corresponding index (most prevalent sequence) of the human viruses. The majority of these avian substitutions were long-standing in the evolution of H7N9, and only 17 were first detected in 2013 as possibly essential for the initial human adaptation. Strikingly, continued evolution of the avian H7N9 virus has resulted in avian and human protein sequences that are almost identical. This rapid and continued adaptation of the avian H7N9 virus to the human host, with near identity of the avian and human viruses, is associated with increased human infection and a predicted greater risk of human-to-human transmission.
甲型流感病毒 A（H7N9）在禽类宿主中循环传播数十年后，于 2013 年被鉴定为人病原体。在此，通过比较 2014 年和 2017 年报告的禽类和人类 H7N9 数据集的 4706 个对齐重叠九肽位置序列（1-9、2-10 等），确定了可能对人类适应至关重要的氨基酸取代。最初的病毒序列集（截至 2014 年）共显示 109 种禽源到人的（A2H）特征性氨基酸取代。每个序列都代表了在给定的禽病毒九肽位置上最普遍的取代，这些取代被选择性地适应为人类病毒的相应指标（最普遍的序列）。这些禽类取代中的大多数在 H7N9 的进化中由来已久，只有 17 种是在 2013 年首次检测到的，可能对人类的最初适应至关重要。引人注目的是，禽 H7N9 病毒的持续进化导致了禽源和人类蛋白序列几乎完全一致。这种禽源 H7N9 病毒对人类宿主的快速和持续适应，以及禽源和人类病毒的近乎一致，与人类感染的增加和预测的人际传播风险增加有关。
