Overview:

The B.1.621 variant emerged from the parental B.1 lineage and was first found in Colombia in January 2021. The World Health Organization (WHO) designated the B.1.621 variant as Mu and classified it as a variant of interest (VOI) in August 2021 (1). The Mu variant (lineage: B.1.621) carries the mutations R346K, E484K, and N501Y on its RBD and the mutations manifest resistance to antiviral immunity. Compared to Delta, the Mu variant shows enhanced immune resistance to antibodies, and the E484K mutation, an escape mutation, is considered to be the reason for reducing the neutralizing ability of antibodies (2). As more variants of the virus emerge, it is pivotal to study the transmissibility, virulence, and their possible tendency to escape antibody neutralization of the virus (3).

Gene Aliases:

2019-nCoV RBD, SARS-CoV-2 spike RBD, novel coronavirus spike RBD, nCoV spike RBD, SARS-CoV-2 Mu variant

Genbank Number:

MN908947

References:

1. Xiaochun, X et al: Emerging SARS-CoV-2 B. 1.621/Mu variant is prominently resistant to inactivated vaccine-elicited antibodies. Zoological Research. 2021, doi: 10.24272/j.issn.2095-8137.2021.343

2. Harvey, W.T, et al. SARS-CoV-2 variants, spike mutations and immune escape. Nat Rev Microbiol. 2021, 19: 409–424.

3. Starr TN, et al: Molecular dynamic simulation reveals E484K mutation enhances spike RBD-ACE2 affinity and the combination of E484K, K417T and N501Y mutations (501Y.V2 variant) induces conformational change greater than N501Y mutant alone, potentially resulting in an escape mutant. Cell. 2020, 182(5):1295-1310.