Analysis of SARS-CoV-2 lineage A.27 prevalent in Germany in spring 2021

In spring 2021, an increasing number of infections was observed caused by the hitherto rarely described SARS-CoV-2 variant A.27 in south-west Germany. From December 2020 to June 2021 this lineage has been detected in 31 countries. Phylogeographic analyses of A.27 sequences obtained from national and international databases reveal a global spread of this lineage through multiple introductions from its inferred origin in Western Africa. Variant A.27 is characterized by a mutational pattern in the spike gene that includes the L18F, L452R and N501Y spike amino acid substitutions found in various variants of concern but lacks the globally dominant D614G. Neutralization assays demonstrated an escape of A.27 from convalescent and vaccine-elicited antibody-mediated immunity. Moreover, the therapeutic monoclonal antibody Bamlanivimab and partially the REGN-COV2 cocktail failed to block infection by A.27. Our data emphasize the need for continued global monitoring of novel lineages because of the independent evolution of new escape mutations.

2021年春季，德国西南部地区出现了越来越多由此前罕有报道的严重急性呼吸综合征冠状病毒2（SARS-CoV-2）变异株A.27引发的感染病例。2020年12月至2021年6月期间，该进化分支已在31个国家被检出。对从各国及国际数据库获取的A.27序列开展系统地理分析后发现，该进化分支从其推断的西非起源地经多次跨区域传播实现了全球扩散。A.27变异株的特征为刺突蛋白基因存在特定突变模式：包含L18F、L452R及N501Y刺突蛋白氨基酸替换——此类突变可见于多种关切变异株，但该变异株缺乏全球流行主流的D614G突变。中和试验结果显示，A.27可逃逸恢复期患者及疫苗接种者体内抗体介导的免疫保护作用。此外，治疗性单克隆抗体巴尼韦单抗（Bamlanivimab）无法阻断A.27感染，REGN-COV2抗体鸡尾酒疗法的阻断效果亦仅部分有效。本研究数据表明，由于逃逸突变可独立演化，因此需持续开展全球范围内的新型病毒进化分支监测工作。