Fast Five Quiz: COVID-19 Omicron Variant

Michael Stuart Bronze, MD


September 20, 2022

Mutations in SARS-CoV-2 resulting in the Omicron variant have led to a higher effective reproduction number compared with other variants, demonstrating great infectivity and transmissibility. Key mutations in the spike protein, particularly at the receptor binding domains, display a much higher affinity for binding to the angiotensin-converting enzyme 2 receptor, which allows for viral entry into the host cell and increased antibody evasion. In previous variants, entry was facilitated by transmembrane serine protease 2, which is not utilized by the Omicron variant.

Mutations outside of the spike protein may play different roles in Omicron's biology. A deletion in nonstructural protein 6 may play a role in evasion of innate immunity, but its potential functional relevance remains to be determined. The genome of Omicron also includes mutations in nucleocapsid proteins, which may be responsible for increased viral load.

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