Strong attenuation of SARS-CoV-2 Omicron BA.1 and increased replication of the BA.5 subvariant in human cardiomyocytes
Rayhane Nchioua, Federica Diofano, Sabrina Noettger, Pascal von Maltitz, Steffen Stenger, Fabian Zech, Jan Münch, Konstantin M. J. Sparrer, Steffen Just, Frank Kirchhoff
Abstract
Since its first description in South Africa in November 2021, the SARS-CoV-2 Omicron variant rapidly outcompeted the previously dominating Delta variant. Omicron is the fifth variant of concern (VOC). It contains an unusually high number of mutations compared to previous VOCs, especially in the viral Spike protein, and shows high transmissibility and efficient escape of neutralizing antibodies. Due to these characteristics, it received this designation much faster than the four previous VOCs Alpha, Beta, Gamma, and Delta. However, the original BA.1 Omicron variant seems to be less pathogenic than early SARS-CoV-2 strains and other VOCs. While SARS-CoV-2 primarily infects the respiratory tract, Coronavirus disease 19 (COVID-19) is a multi-organ disease, and patients show infection and disorders in the gastrointestinal, cardiovascular, and neurological systems. Thus, the ability of the various SARS-CoV-2 variants to infect and propagate in different cell types and organs clearly plays a key role in viral pathogenicity. Especially, cardiomyocytes express high levels of the primary SARS-CoV-2 receptor ACE2 and are highly permissive for viral replication.