Division of Viral Products, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA.
Division of Veterinary Services, Center for Biologics Evaluation and Research, US Food and Drug Administration, Silver Spring, MD, USA.
Life Sci Alliance. 2021 Feb 11;4(4). doi: 10.26508/lsa.202000886. Print 2021 Apr.
A critical question in understanding the immunity to SARS-COV-2 is whether recovered patients are protected against re-challenge and transmission upon second exposure. We developed a Syrian hamster model in which intranasal inoculation of just 100 TCID virus caused viral pneumonia. Aged hamsters developed more severe disease and even succumbed to SARS-CoV-2 infection, representing the first lethal model using genetically unmodified laboratory animals. After initial viral clearance, the hamsters were re-challenged with 10 TCID SARS-CoV-2 and displayed more than 4 log reduction in median viral loads in both nasal washes and lungs in comparison to primary infections. Most importantly, re-challenged hamsters were unable to transmit virus to naïve hamsters, and this was accompanied by the presence of neutralizing antibodies. Altogether, these results show that SARS-CoV-2 infection induces protective immunity that not only prevents re-exposure but also limits transmission in hamsters. These findings may help guide public health policies and vaccine development and aid evaluation of effective vaccines against SARS-CoV-2.
理解对 SARS-CoV-2 免疫力的一个关键问题是，康复患者是否能防止二次暴露时再次感染和传播。我们开发了一种叙利亚仓鼠模型，其中鼻内接种仅 100TCID 病毒就会导致病毒性肺炎。年老的仓鼠会发展出更严重的疾病，甚至死于 SARS-CoV-2 感染，这是首次使用未经基因改造的实验室动物建立的致死模型。初始病毒清除后，仓鼠用 10TCID SARS-CoV-2 再次感染，与初次感染相比，鼻腔冲洗液和肺部的中位数病毒载量降低了超过 4 个对数级。最重要的是，再次感染的仓鼠无法将病毒传播给未感染的仓鼠，这伴随着中和抗体的存在。总的来说，这些结果表明，SARS-CoV-2 感染诱导了保护性免疫，不仅可以防止再次暴露，还可以限制仓鼠中的传播。这些发现可能有助于指导公共卫生政策和疫苗开发，并有助于评估针对 SARS-CoV-2 的有效疫苗。
