Maximum Containment Laboratory, Indian Council of Medical Research-National Institute of Virology (ICMR-NIV), Pune, Maharashtra 411021, India.
Maximum Containment Laboratory, Indian Council of Medical Research-National Institute of Virology (ICMR-NIV), Pune, Maharashtra 411021, India.
EBioMedicine. 2022 May;79:103997. doi: 10.1016/j.ebiom.2022.103997. Epub 2022 Apr 8.
SARS-CoV-2 Omicron variant is rampantly spreading across the globe. We assessed the pathogenicity and immune response generated by BA.1.1 sub-lineage of SARS-CoV-2 [Omicron (R346K) variant] in 5 to 6-week old Syrian hamsters and compared the observations with that of Delta variant infection.
Virus shedding, organ viral load, lung disease and immune response generated in hamsters were sequentially assessed.
The disease characteristics of the Omicron (R346K) variant were found to be similar to that of the Delta variant infection in hamsters like viral replication in the respiratory tract and interstitial pneumonia. The Omicron (R346K) infected hamsters demonstrated lesser body weight reduction and viral RNA load in the throat swab and nasal wash samples in comparison to the Delta variant infection. The viral load in the lungs and nasal turbinate samples and the lung disease severity of the Omicron (R346K) infected hamsters were found comparable with that of the Delta variant infected hamsters. Neutralizing antibody response against Omicron (R346K) variant was detected from day 5 and the cross-neutralization titre of the sera against other variants showed severe reduction ie., 7 fold reduction against Alpha and no titers against B.1, Beta and Delta.
This preliminary data shows that Omicron (R346K) variant infection can produce moderate to severe lung disease similar to that of the Delta variant and the neutralizing antibodies produced in response to Omicron (R346K) variant infection shows poor neutralizing ability against other co-circulating SARS-CoV-2 variants like Delta which necessitates caution as it may lead to increased cases of reinfection.
This study was supported by Indian Council of Medical Research as an intramural grant (COVID-19) to ICMR-National Institute of Virology, Pune.
SARS-CoV-2 奥密克戎变体正在全球范围内迅速传播。我们评估了 SARS-CoV-2 BA.1.1 亚谱系[奥密克戎（R346K）变体]在 5 至 6 周龄叙利亚仓鼠体内产生的致病性和免疫应答，并将观察结果与德尔塔变体感染进行了比较。
依次评估了病毒脱落、器官病毒载量、肺部疾病和仓鼠体内产生的免疫应答。
奥密克戎（R346K）变体在仓鼠中的疾病特征与德尔塔变体感染相似，例如呼吸道和间质性肺炎中的病毒复制。与德尔塔变体感染相比，奥密克戎（R346K）感染的仓鼠在体重减轻和咽喉拭子和鼻腔冲洗样本中的病毒 RNA 载量方面表现出较小的变化。奥密克戎（R346K）感染仓鼠的肺部和鼻甲骨样本中的病毒载量以及肺部疾病严重程度与德尔塔变体感染的仓鼠相当。从第 5 天开始检测到针对奥密克戎（R346K）变体的中和抗体应答，而针对其他变体的血清交叉中和效价显示出严重降低，即对 Alpha 降低 7 倍，对 B.1、Beta 和 Delta 则无滴度。
这项初步数据表明，奥密克戎（R346K）变体感染可引起类似于德尔塔变体的中度至重度肺部疾病，而针对奥密克戎（R346K）变体感染产生的中和抗体对其他循环的 SARS-CoV-2 变体（如德尔塔）的中和能力较差，这需要谨慎，因为它可能导致再感染病例增加。
这项研究得到印度医学研究理事会的支持，作为印度医学研究理事会-国家病毒学研究所，浦那的一项内部拨款（COVID-19）。
