水貂与2019冠状病毒病:如何利用核衍生技术检测病毒新毒株并预防大流行病

国际原子能机构(原子能机构)与联合国粮食及农业组织(粮农组织)结伴为世界各国提供的核衍生工具在研究、检测、诊断及表征2019冠状病毒病等人畜共患疾病方面发挥了重要作用。

实时逆转录-聚合酶链反应是最准确的2019冠状病毒病病毒检测方法。数十年来,原子能机构与粮农组织一直结伴帮助各国利用该技术检测人畜共患疾病。(照片来源:D. Calma/原子能机构)

国际原子能机构(原子能机构)与联合国粮食及农业组织(粮农组织)结伴为世界各国提供的核衍生工具在研究、检测、诊断及表征 2019冠状病毒病等人畜共患疾病方面发挥了重要作用。它们还是了解和追踪病毒变异的重要工具。最近在荷兰和丹麦的发现首次记录了2019冠状病毒病感染可由人类传播给水貂继而回传人类的情况,这表明病毒能快速适应新宿主。了解这些变异对于研发针对引起2019冠状病毒病的病毒以及其他相似病毒的有效疫苗至关重要。

原子能机构与粮农组织已搭建推动与便利世界各地的实验室获取基因测序技术的平台,以促进深入了解在本地传播或传入本地的病原体。迄今为止,原子能机构已有使用了各种病毒包括冠状病毒的基因测序服务的3000多份对口实验室提交的论文和24份出版物发表在同行评审期刊上。

“最近在丹麦水貂养殖场的发现突显了持续监测和监视动物-人类界面的必要性。同样必要的是,全世界的科学家和实验室将可用且适当的诊断和监视工具用于早期快速检测及表征病原体、监测其演变并及时发掘演变出现的新病原体。”粮农组织/原子能机构粮农核技术联合处牧业生产和健康科科长Gerrit Viljoen说。

2019冠状病毒病病毒在水貂体内变异

“问题在于我们尚不清楚病毒如何在水貂体内发生了变异,”Viljoen说。“现在,尽管病毒传播给水貂并继而回传人类的过程引起了基因变异,但变异毒株只是对人类中和抗体的敏感性略微降低,而且情况还会变化。病毒如果在适应多个宿主时发生结构改变,一旦回传人类则会呈现高度致病性并更易致死。”这可能构成影响未来疫苗的有效性的风险。

根据世界卫生组织(世卫组织)报告,自2020年6月以来,在丹麦已发现214例与养殖水貂相关的病毒变异株所致的2019冠状病毒病人类病例。西班牙、瑞典、意大利和荷兰的水貂养殖场也报告了类似的感染。在丹麦发现的病毒变异株具有之前未观察到的基因突变组合。目前尚不清楚这种新毒株是否对人类更危险,但是该病毒表现出的对能够中和其感染性的抗体的敏感性已经有所下降。

水貂是首个被发现能够被人类感染也能感染人类的动物物种,但是它们可能不是唯一的。原子能机构通过知识传播和设备转让已经协助超过120个国家检测引起2019冠状病毒病的病毒。数十年来,在血清学和分子检测技术方面,以及在动物和人类病毒(包括冠状病毒)的基因测序和表征方面,原子能机构一直在向发展中国家的兽医实验室提供支助(见21世纪的冠状病毒)。

逆转录-聚合酶链反应等核衍生工具正用于研究与丹麦水貂以及水貂养殖人员相关的情况。

“人畜共患疾病综合行动”倡议

ZODIAC(“人畜共患疾病综合行动”)是原子能机构发起的新倡议,旨在预防和控制未来由动物传播给人类的疾病的爆发。该倡议将扩大并升级兽医诊断实验室网,使各兽医实验室能通过该网络交流信息、共享最佳实践并且互相给予支持。该倡议将有助于国家实验室监测、监视、早期检测和控制2019冠状病毒病、埃博拉病毒病、禽流感及寨卡等动物疾病和人畜共患疾病。人畜共患疾病每年导致约270万人死亡。

COVID-19 virus modified by mink

“The problem is that we do not, yet, know how the virus is being modified in mink,” Viljoen said. “Right now, despite the genetic changes crossed by the transmission to and from mink, the virus strain has only become slightly less sensitive to human neutralizing antibodies, but this could change. If the virus changes its structure while adapting to multiple hosts, it can become highly pathogenic and more fatal to people once it comes back to humans.” This could pose a risk to the efficacy of future vaccines.

Since June 2020, 214 human cases of COVID-19 have been identified in Denmark with virus variants associated with farmed mink, according to the World Health Organization (WHO). Similar infections were reported from mink farms in Spain, Sweden, Italy and the Netherlands. The virus identified in Denmark had a combination of genetic mutations that had not previously been observed. It is not clear at this point whether this new strain is more dangerous for humans, but the virus has shown decreased sensitivity to antibodies able to neutralize virus infectivity.

Mink are the first animal species identified that can be infected by people and vice versa – but they may not be the only ones. The IAEA, which has already assisted over 120 countries by transferring knowledge and equipment to detect the virus that causes COVID-19, has for decades been supporting veterinary laboratories in developing countries in serological and molecular detection techniques, as well as in the genetic sequencing and characterization of viruses, including coronaviruses in both animals and people (see Coronaviruses in the 21st century).

Nuclear-derived tools, such as RT-PCR, are being utilized in the situation surrounding mink and the farmers tending to mink in Denmark.

The ZODIAC initiative

ZODIAC (Zoonotic Disease Integrated Action), a new IAEA initiative aimed at preventing and controlling future outbreaks of diseases that spread from animals to humans, will expand and upgrade the VETLAB network, through which veterinary labs exchange information, share best practices and support each other. It will help national laboratories in monitoring, surveillance, early detection and control of animal and zoonotic diseases, such as COVID-19, Ebola, avian influenza and Zika. Zoonotic diseases kill around 2.7 million people every year.