BW.1- a brand new Omicron subvariant that escapes immunity

The extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal agent of the coronavirus illness 2019 (COVID-19), continues to evolve by way of genomic mutations. Rising SARS-CoV-2 variants have been categorized as variants of curiosity (VOI) and variants of concern (VOC) primarily based on their infectiousness, virulence, and capability to evade immune responses induced by way of each pure an infection and vaccination.

Research: SARS-CoV-2 BW.1, a fast-growing Omicron variant from southeast Mexico bearing relevant escape mutations. Picture Credit score: Ebrahim Lotfi /


At current, the SARS-CoV-2 Omicron variant is dominantly circulating in most nations of the world. The continuous genomic mutations of the Omicron variant have resulted within the emergence of a number of subvariants, thus emphasizing the significance of standard genomic surveillance.

A brand new examine printed on the Research Square preprint server* experiences the presence of mutations that assist in immune escape within the BW.1 (BA. pressure, which is an Omicron subvariant descending from the BA.5.6.2 lineage. 

SARS-CoV-2 BW.1 incorporates mutations which are much like the BQ.1 variant and assist in immune escape. BQ.1 is without doubt one of the most quickly transmitting lineages and incorporates a number of mutations, resembling S:K444T, S:L452R, S:N460K, and S:F486V.

Within the present examine, the authors suspect that BW.1 might have emerged in Mexico in early July. By October, BW.1 was the dominantly circulating pressure within the Yucatan Peninsula.

Mexico is a crucial Latin American nation that has extensively sequenced SARS-CoV-2 genomes. Earlier research have reported that the Yucatan Peninsula is without doubt one of the key entry routes of SARS-CoV-2 variants in Mexico on account of a considerably giant proportion of vacationer inflow and business actions.

Concerning the examine

Genomic sequences and the related metadata of BQ.1, BA.5.6.2, and BW.1 have been obtained from GISAID. All related genomic sequences together with lineage information-based PANGO v.4.1.3 have been collected on November 7, 2022.

Genomic alignment and phylogenetic reconstruction evaluation of BW.1 and its parental variant BA.5.6.2 have been carried out utilizing a number of sequence alignments (MSA) beneath Nextstrain’s default pipeline. Genomic alignment helped detect mutations of BW.1 and phylogenetic reconstruction enabled tracing again to their origin.

Key findings

Though Mexico is at present present process a part of low COVID-19 incidence after a BA.2/BA.5 pushed wave, the genomic evaluation of samples collected from Yucatan over the previous a number of weeks exhibited a big prevalence of the BW.1 variant.

Curiously, researchers noticed that in October, the Yucatan Peninsula skilled a surge in COVID-19 instances/ Throughout on this interval, the BW.1 variant outcompeted different SARS-CoV-2 variants that have been current within the area, together with its parental variant.

The genomic evaluation strongly indicated that BW.1 might have originated in Mexico throughout its fifth epidemiological wave and originated from BA.5.6.2 strains that have been reported to be circulating within the state of Yucatan throughout that interval. Curiously, out of the entire of 105 BW.1 genomic sequences collected from the GISAID database, 95 have been collected in Mexico.

Two synonymous substitutions of BW.1 have been traced again to Mexican sequences of BA.5.6.2 genomes. Solely two mutations have been detected that differentiated Mexican BA.5.6.2 from Omicron strains present in the remainder of the world. The nucleotide transition, T7666C, which was current in 2,458 sequences worldwide and 82.48% of all BA.5.6.2 sequences, was absent in Mexican BA.5.6.2 genomes together with BW.1.

Evaluation of Mexican genomic sequences revealed that BA.5.6.2 and BW.1 sequences shared the synonymous substitution C14599T, which was current in solely 4% of BA.5.6.2 sequences throughout the remainder of the world.

The vast majority of genomic sequences of BW.1 have been dissimilar to the parental BA.5.6.2 by two-point mutations. The presence of nucleotide transition G2144A and transversion T22942G have been noticed in 98.09% and 92.38% of the BW.1 genome, respectively. Notably, the parental BA.5.6.2 group didn’t include the T22942G mutation, which was first detected in BW.1 pressure sequenced in Mexico in early August.

Though the BW.1 variant descended from Omicron lineage BA.5.6, its genome shares a standard evolutionary historical past with BQ.x variants. It’s because each BW.1 and BQ.x descended from the BA.5 lineage.

Each of those subvariants inherited greater than 54 mutations, together with S:L452R, which is related to elevated infectivity, conferring spike stability, and selling viral fusogenicity. In addition they include the S:F486V mutation, which is related to lowered efficacy of a number of monoclonal antibodies.

Each BQ.1 and BW.1 variants include vital extra BD mutations, together with S:K444T and S:N460K, which improve viral resistance to bebtelovimab and hinder antibody recognition, thereby enabling immune escape. The presence of the S:N460K mutation enhances fusogenicity and resistance to neutralization.


The authors of the present examine emphasised the significance of genomic surveillance and monitoring of mutations that would make clear figuring out SARS-CoV-2 strains adversely affecting the worldwide human inhabitants. There’s a excessive chance that the BW.1 pressure might improve COVID-19 instances worldwide. 

*Vital discover

Analysis Sq. publishes preliminary scientific experiences that aren’t peer-reviewed and, subsequently, shouldn’t be thought to be conclusive, information medical apply/health-related conduct, or handled as established info.

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