General information on SARS-CoV-2 RBD of Spike protein, R346K, E484K, N501Y – B.1.621 lineage – Colombian Mu variant
Lineage B.1.621 is predicted to have originated in January 2021 in Colombia. This variant shows a convergence of amino acid mutations on the spike protein of SARS-CoV-2. Many of these changes were found on the receptor-binding domain (RBD) of the virus, responsible for binding the human receptor ACE2 and initiating the infection in the upper respiratory tract. Noteworthy mutations on lineage B.1.621 are the E484K amino acid change, previously detected in lineages Alpha (UK), Beta (South Africa), and Gamma (Brazil), and found to correlate with increased resistance to convalescent plasma therapy and, consequently, natural neutralizing activity. Additionally, this variant was shown to carry the N501Y, already quite prevalent among SARS-CoV-2 circulating variants, and shown to correlate with improved viral transmission. In contrast, it is the first time that the amino acid change R346K has been detected in dominant circulating variants of the virus responsible for the COVID-19 disease. This mutation has been tentatively associated with increased resistance to neutralizing antibodies.
Due to the accumulation of these mutations, current COVID-19 vaccines were found to be slightly less effective against the variant and the Public Health England (PHE) has recently classified it as a Variant Under Investigation (VUI) and named it VUI-21JUL-01. SARS-CoV-2 sequences of this lineage have been since spread from their place of origin in Colombia to Mexico, Spain, Ecuador, and the United States of America where they are currently one of the most dangerous and fastest-growing variants of the region. More studies are necessary to determine if this new variant causes more severe cases of the COVID-19 disease.