Indian Council of Medical Research-National Institute of Virology, Pune 411021, India.
Department of Veterinary Pathology, Krantisinh Nana Patil College of Veterinary Science, Shirwal 412801, India.
Viruses. 2022 Mar 13;14(3):596. doi: 10.3390/v14030596.
The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) Delta variant has evolved to become the dominant SARS-CoV-2 lineage with multiple sub-lineages and there are also reports of re-infections caused by this variant. We studied the disease characteristics induced by the Delta AY.1 variant and compared it with the Delta and B.1 variants in Syrian hamsters. We also assessed the potential of re-infection by these variants in Coronavirus disease 2019 recovered hamsters 3 months after initial infection. The variants produced disease characterized by high viral load in the respiratory tract and interstitial pneumonia. The Delta AY.1 variant produced mild disease in the hamster model and did not show any evidence of neutralization resistance due to the presence of the K417N mutation, as speculated. Re-infection with a high virus dose of the Delta and B.1 variants 3 months after B.1 variant infection resulted in reduced virus shedding, disease severity and increased neutralizing antibody levels in the re-infected hamsters. The reduction in viral load and lung disease after re-infection with the Delta AY.1 variant was not marked. Upper respiratory tract viral RNA loads remained similar after re-infection in all the groups. The present findings show that prior infection could not produce sterilizing immunity but that it can broaden the neutralizing response and reduce disease severity in case of reinfection.
严重急性呼吸综合征冠状病毒 2 型（SARS-CoV-2）Delta 变体已经进化成为主要的 SARS-CoV-2 谱系，有多个亚谱系，也有报告称该变体导致再感染。我们研究了 Delta AY.1 变体引起的疾病特征，并将其与 Delta 和 B.1 变体在叙利亚仓鼠中进行了比较。我们还评估了这些变体在初次感染 3 个月后从新冠肺炎中恢复的仓鼠中再次感染的可能性。这些变体引起的疾病特征是呼吸道和间质性肺炎中的病毒载量高。Delta AY.1 变体在仓鼠模型中引起轻度疾病，由于存在 K417N 突变，并没有表现出中和抗体耐药性的任何证据，这与推测一致。在 B.1 变体感染 3 个月后，用高病毒剂量再次感染 Delta 和 B.1 变体导致病毒脱落减少、疾病严重程度降低和再感染仓鼠的中和抗体水平升高。再感染 Delta AY.1 变体后病毒载量和肺部疾病的减少并不明显。所有组在再次感染后上呼吸道病毒 RNA 载量保持相似。本研究结果表明，先前的感染不能产生绝育性免疫，但可以扩大中和反应，并在再次感染时降低疾病严重程度。
