Abstract:
Environmental factors play a key role in the zoonotic transmission of emerging pathogenic viruses as mankind is constantly disturbing wildlife\'s ecosystems usually by cutting down forests to build human settlements or by catching wild animals for food, which deprives the viruses of their natural hosts and gives them opportunity to infect humans. In December 2019, a new coronavirus emerged from bats and was named SARS-CoV-2 by the International Committee for Taxonomy of Viruses, and the disease it causes named COVID-19 by the World Health Organization. Disease outbreaks such as SARS in 2002-2003, MERS in 2012 and the current COVID-19 pandemic are the result of higher mutation rates of coronaviruses and their unique capacity for genetic recombination, resulting in adaptations that make them more suitable to cross the species barriers and infect other species. This ability for host switching and interspecies infection is often attributed to the great diversity of these viruses, which is a result of viral and host factors such as the low fidelity of their RNA-dependent RNA polymerase, the high frequency of their homologous RNA recombination, and the adaptation of the S protein to bind host receptors like the angiotensin converting enzyme 2 (ACE2) in the case of SARS-CoV and SARS-CoV-2, and dipeptidyl peptidase 4 (DDP4) in MERS-CoV. This review presents an overview of the zoonotic transmission of SARS, MERS and COVID-19, focusing on the viral, host and environmental factors that favor the spillover of these viruses into humans, as well as the biological and ecological factors that make bats the perfect animal reservoir of infection for these viruses.
摘要:
环境因素在新出现的病原病毒的人畜共患传播中起着关键作用,因为人类经常通过砍伐森林以建立人类住区或捕获野生动物作为食物来干扰野生动物的生态系统,这剥夺了病毒的自然宿主,并给了它们感染人类的机会。2019年12月,一种新的冠状病毒从蝙蝠身上出现,被国际病毒分类委员会命名为SARS-CoV-2,以及它引起的疾病被世界卫生组织命名为COVID-19。2002-2003年的SARS,2012年的MERS和当前的COVID-19大流行等疾病暴发是冠状病毒突变率较高及其独特的基因重组能力的结果,导致适应,使它们更适合跨越物种障碍并感染其他物种。这种宿主转换和种间感染的能力通常归因于这些病毒的多样性,这是病毒和宿主因素的结果,如RNA依赖性RNA聚合酶的低保真度,它们的同源RNA重组的高频率,在SARS-CoV和SARS-CoV-2的情况下,S蛋白适应结合宿主受体如血管紧张素转化酶2(ACE2),在MERS-CoV的情况下,二肽基肽酶4(DDP4)。这篇综述概述了SARS的人畜共患传播,MERS和COVID-19,专注于病毒,宿主和环境因素有利于这些病毒溢出到人类,以及使蝙蝠成为这些病毒感染的完美动物宿主的生物和生态因素。