Complex Mutation Pattern of Omicron BA.2: Evading Antibodies without Losing Receptor Interactions

Phylogeny and evolution of SARS-CoV-2 during Delta and Omicron variant waves in India

SARS-CoV-2 evolution has continued to generate variants, responsible for new pandemic waves locally and globally. Varying disease presentation and severity has been ascribed to inherent variant characteristics and vaccine immunity. This study analyzed genomic data from 305 whole genome sequences from SARS-CoV-2 patients before and through the third wave in India. Delta variant was reported in patients without comorbidity (97%), while Omicron BA.2 was reported in patients with comorbidity (77%). Tissue adaptation studies brought forth higher propensity of Omicron variants to bronchial tissue than lung, contrary to observation in Delta variants from Delhi. Study of codon usage pattern distinguished the prevalent variants, clustering them separately, Omicron BA.2 isolated in February grouped away from December strains, and all BA.2 after December acquired a new mutation S959P in ORF1b (44.3% of BA.2 in the study) indicating ongoing evolution. Loss of critical spike mutations in Omicron BA.2 and gain of immune evasion mutations including G142D, reported in Delta but absent in BA.1, and S371F instead of S371L in BA.1 could explain very brief period of BA.1 in December 2021, followed by complete replacement by BA.2. Higher propensity of Omicron variants to bronchial tissue, probably ensured increased transmission while Omicron BA.2 became the prevalent variant possibly due to evolutionary trade-off. Virus evolution continues to shape the epidemic and its culmination.Communicated by Ramaswamy H. Sarma.

Deciphering ACE2-RBD binding affinity through peptide scanning: A molecular dynamics simulation approach

Rapid discovery of target information for protein-protein interactions (PPIs) is significant in drug design, diagnostics, vaccine development, antibody therapy, etc. Peptide microarray is an ideal tool for revealing epitope information of PPIs. In this work, the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) spike receptor-binding domain (RBD) and the host cell receptor angiotensin-converting enzyme 2 (ACE2) were introduced as a model to study the epitope information of RBD-specific binding to ACE2 via a combination of theoretical calculations and experimental validation. Through dock and molecular dynamics simulations, it was found that among the 22 peptide fragments that consist of RBD, #14 (YNYLYRLFRKSNLKP) has the highest binding strength. Subsequently, the experiments of peptide microarray constructed based on plasmonic materials chip also confirmed the theoretical calculation data. Compared to other methods, such as phage display technology and surface plasmon resonance (SPR), this method is rapid and cost-effective, providing insights into the investigation of pathogen invasion processes and the timely development of peptide drugs and other fields.

Genomic surveillance of omicron B.1.1.529 SARS-CoV-2 and its variants between December 2021 and March 2023 in Tamil Nadu, India-A state-wide prospective longitudinal study

A state-wide prospective longitudinal investigation of the genomic surveillance of the omicron B.1.1.529 SARS-CoV-2 variant and its sublineages in Tamil Nadu, India, was conducted between December 2021 and March 2023. The study aimed to elucidate their mutational patterns and their genetic interrelationship in the Indian population. The study identified several unique mutations at different time-points, which likely could attribute to the changing disease characteristics, transmission, and pathogenicity attributes of omicron variants. The study found that the omicron variant is highly competent in its mutating potentials, and that it continues to evolve in the general population, likely escaping from natural as well as vaccine-induced immune responses. Our findings suggest that continuous surveillance of viral variants at the global scenario is warranted to undertake intervention measures against potentially precarious SARS-CoV-2 variants and their evolution.

Effectiveness of various COVID-19 vaccine regimens among 10.4 million patients from the National COVID Cohort Collaborative during Pre-Delta to Omicron periods - United States, 11 December 2020 to 30 June 2022

OBJECTIVE

This study reports the vaccine effectiveness (VE) of COVID-19 vaccine regimens in the United States, based on the National COVID Cohort Collaborative (N3C) database.

METHODS

Data from 10.4 million adults, enrolled in the N3C from 11 December 2020 to 30 June 2022, were analyzed. VE against infection and death outcomes were evaluated across 13 vaccine regimens in recipient cohorts during the Pre-Delta, Delta, and Omicron periods. VE was estimated as (1-odds ratio) × 100% by multivariate logistic regression, using the unvaccinated cohort as reference.

RESULTS

Natural immunity showed a highly protective effect (70.33%) against re-infection, but the mortality risk among the unvaccinated population was increased after re-infection; vaccination following infection reduced the risk of re-infection and death. mRNA-1273 full vaccination plus mRNA-1273 booster showed the highest anti-infection effectiveness (47.59%) (95% CI, 46.72-48.45) in the overall cohort. In the type 2 diabetes cohort, VE against infection was highest with BNT162b2 full vaccination plus mRNA-1273 booster (61.19%) (95% CI, 53.73-67.75). VE against death was also highest with BNT162b2 full vaccination plus mRNA-1273 booster (89.56%) (95% CI, 85.75-92.61). During the Pre-Delta period, all vaccination regimens showed an anti-infection effect; during the Delta period, only boosters, mixed vaccines, and Ad26.COV2.S vaccination exhibited an anti-infection effect; during the Omicron period, none of the vaccine regimens demonstrated an anti-infection effect. Irrespective of the variant period, even a single dose of mRNA vaccine offered protection against death, thus demonstrating survival benefit, even in the presence of infection or re-infection. Similar patterns were observed in patients with type 2 diabetes.

CONCLUSIONS

Although the anti-infection effect declined as SARS-CoV-2 variants evolved, all COVID-19 mRNA vaccines had sustained effectiveness against death. Vaccination was crucial for preventing re-infection and reducing the risk of death following SARS-CoV-2 infection.

Continued Complexity of Mutations in Omicron Sublineages

The latest SARS-CoV-2 variant of concern (VOC), Omicron (B.1.1.529), has diversified into more than 300 sublineages. With an expanding number of newly emerging sublineages, the mutation profile is also becoming complicated. There exist mutually exclusive and revertant mutations in different sublineages. Omicron sublineages share some common mutations with previous VOCs (Alpha, Beta, Gamma, and Delta), indicating an evolutionary relationship between these VOCs. A diverse mutation profile at the spike–antibody interface, flexibility of the regions harboring mutations, mutation types, and coexisting mutations suggest that SARS-CoV-2’s evolution is far from over.

Omicron BA.2 Lineage, the "Stealth" Variant: Is It Truly a Silent Epidemic? A Literature Review

The epidemic curve of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is silently rising again. Worldwide, the dominant SARS-CoV-2 variant of concern (VOC) is Omicron, and its virological characteristics, such as transmissibility, pathogenicity, and resistance to both vaccine- and infection-induced immunity as well as antiviral drugs, are an urgent public health concern. The Omicron variant has five major sub-lineages; as of February 2022, the BA.2 lineage has been detected in several European and Asian countries, becoming the predominant variant and the real antagonist of the ongoing surge. Hence, although global attention is currently focused on dramatic, historically significant events and the multi-country monkeypox outbreak, this new epidemic is unlikely to fade away in silence. Many aspects of this lineage are still unclear and controversial, but its apparent replication advantage and higher transmissibility, as well as its ability to escape neutralizing antibodies induced by vaccination and previous infection, are rising global concerns. Herein, we review the latest publications and the most recent available literature on the BA.2 lineage of the Omicron variant.

Genome Evolution and Early Introductions of the SARS-CoV-2 Omicron Variant in Mexico

A new variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), named Omicron (Pango lineage designation B.1.1.529), was first reported to the World Health Organization by South African health authorities on 24 November 2021. The Omicron variant possesses numerous mutations associated with increased transmissibility and immune escape properties. In November 2021, Mexican authorities reported Omicron's presence in the country. In this study, we infer the first introductory events of Omicron and the impact that human mobility has had on the spread of the virus. We also evaluated the adaptive evolutionary processes in Mexican SARS-CoV-2 genomes during the first month of the circulation of Omicron. We inferred 160 introduction events of Omicron in Mexico since its first detection in South Africa; subsequently, after the first introductions there was an evident increase in the prevalence of SARS-CoV-2 during January. This higher prevalence of the novel variant resulted in a peak of reported cases; on average 6 weeks after, a higher mobility trend was reported. During the peak of cases in the country from January to February 2022, the Omicron BA.1.1 sub-lineage dominated, followed by the BA.1 and BA.15 sub-lineages. Additionally, we identified the presence of diversifying natural selection in the genomes of Omicron and found six non-synonymous mutations in the receptor binding domain of the spike protein, all of them related to evasion of the immune response. In contrast, the other proteins in the genome are highly conserved; however, we identified homoplasic mutations in non-structural proteins, indicating a parallel evolution.