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The virus that causes severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) belongs to the genus Beta coronavirus and the family Coronaviridae. The SARS-CoV-2 virus is a positive sense, non-segmented single-strand RNA virus that causes coronavirus disease 2019 (COVID-19), which was first reported in December 2019 in Wuhan, China. COVID-19 is now a worldwide pandemic. Globally, several newer variants have been identified; however, only a few of them are of concern (VOCs). VOCs differ in terms of infectivity, transmissibility, disease severity, drug efficacy, and neutralization efficacy by monoclonal antibodies, convalescent sera, or vaccines. VOCs reported from various parts of the world include B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617/B.1.617.2 (Delta), P.1 (Gamma), and B.1.1.529 (Omicron). These VOCs are the result of mutations, with some based on spike proteins. Mutations may also cause molecular diagnostic tests to fail to detect the few VOCs, leading to a delayed diagnosis, increased community spread, and delayed treatment. We searched PubMed, EMBASE, Covariant, Stanford variants database, and CINAHL from December 2019 to February 2022 using the following search terms: Variant of Concern, SARS-CoV-2, Omicron, etc. All types of research were chosen. All research methods were considered. This review discusses the various VOCs, as well as their mutations, infectivity, transmissibility, and neutralization efficacy.

SARS-CoV-2 receptor-binding domain (RBD) is a major target for the development of diagnostics, vaccines and therapeutics directed against COVID-19. Important efforts have been dedicated to the rapid and efficient production of recombinant RBD proteins for clinical and diagnostic applications. One of the main challenges is the ongoing emergence of SARS-CoV-2 variants that carry mutations within the RBD, resulting in the constant need to design and optimise the production of new recombinant protein variants. We describe here the impact of naturally occurring RBD mutations on the secretion of a recombinant Fc-tagged RBD protein expressed in HEK 293 cells. We show that mutation E484K of the B.1.351 variant interferes with the proper disulphide bond formation and folding of the recombinant protein, resulting in its retention into the endoplasmic reticulum (ER) and reduced protein secretion. Accumulation of the recombinant B.1.351 RBD-Fc fusion protein in the ER correlated with the upregulation of endogenous ER chaperones, suggestive of the unfolded protein response (UPR). Overexpression of the chaperone and protein disulphide isomerase PDIA2 further impaired protein secretion by altering disulphide bond formation and increasing ER retention. This work contributes to a better understanding of the challenges faced in producing mutant RBD proteins and can assist in the design of optimisation protocols. [ABSTRACT FROM AUTHOR]

• Neutralization antibody were measured against SARS-CoV-2 variants after vaccination. • Low neutralization antibody titer was observed against beta and delta variants. • Neutralization antibody titer against R.1 lineage was equivalent to original Wuhan. • The weakened humoral response might not be caused solely by the E484K mutation. The reduced vaccine efficacy against the SARS-CoV-2 variant lineage B. 1.351 (beta variant) containing the E484K and N501Y mutations is well known. The E484K mutation in SARS-CoV-2 is thought to be responsible for weakened humoral immunity. Vaccine efficacy against the R.1 lineage, which contains the E484K mutation but not the N501Y mutation, is uncertain. Serum samples were collected from 100 healthy Japanese participants three weeks after receiving the second dose of the BNT162b2 vaccine, and serum neutralization antibody titers were measured against five SARS-CoV-2 variants. The geometric mean neutralization titers measured for the original and R.1 lineages were equivalent (91.90 ± 2.40 and 102.67 ± 2.28, respectively), whereas a low titer was measured for the beta variant (18.03 ± 1.92). Although further investigations with other variant strains and serum samples are essential, our results imply that the weakened humoral response is not caused solely by the E484K mutation. (UMIN000043340). [ABSTRACT FROM AUTHOR]

A severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.1.345 variant carrying the E484K mutation was detected in 4 patients with no apparent epidemiological association from a hospital network in upstate New York. Subsequent analysis identified an additional 11 B.1.1.345 variants from this region between December 2020 and February 2021. [ABSTRACT FROM AUTHOR]

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) belongs to the genus Beta coronavirus and the family of Coronaviridae. It is a positive-sense, non-segmented single-strand RNA virus. Four common types of human coronaviruses circulate globally, particularly in the fall and winter seasons. They are responsible for 10%-30% of all mild upper respiratory tract infections in adults. These are 229E, NL63 of the Alfacoronaviridae family, OC43, and HKU1 of the Betacoronaviridae family. However, there are three highly pathogenic human coronaviruses: SARS-CoV-2, Middle East respiratory syndrome coronavirus, and the latest pandemic caused by the SARS-CoV-2 infection. All viruses, including SARS-CoV-2, have the inherent tendency to evolve. SARS-CoV-2 is still evolving in humans. Additionally, due to the development of herd immunity, prior infection, use of medication, vaccination, and antibodies, the viruses are facing immune pressure. During the replication process and due to immune pressure, the virus may undergo mutations. Several SARS-CoV-2 variants, including the variants of concern (VOCs), such as B.1.1.7 (Alpha), B.1.351 (Beta), B.1.617/B.1.617.2 (Delta), P.1 (Gamma), and B.1.1.529 (Omicron) have been reported from various parts of the world. These VOCs contain several important mutations; some of them are on the spike proteins. These mutations may lead to enhanced infectivity, transmissibility, and decreased neutralization efficacy by monoclonal antibodies, convalescent sera, or vaccines. Mutations may also lead to a failure of detection by molecular diagnostic tests, leading to a delayed diagnosis, increased community spread, and delayed treatment. We searched PubMed, EMBASE, Covariant, the Stanford variant Database, and the CINAHL from December 2019 to February 2023 using the following search terms: VOC, SARS-CoV-2, Omicron, mutations in SARS-CoV-2, etc. This review discusses the various mutations and their impact on infectivity, transmissibility, and neutralization efficacy., Competing Interests: Conflict-of-interest statement: Authors declare no conflicts of interest while publishing this research work., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

SARS-CoV-2 receptor-binding domain (RBD) is a major target for the development of diagnostics, vaccines and therapeutics directed against COVID-19. Important efforts have been dedicated to the rapid and efficient production of recombinant RBD proteins for clinical and diagnostic applications. One of the main challenges is the ongoing emergence of SARS-CoV-2 variants that carry mutations within the RBD, resulting in the constant need to design and optimise the production of new recombinant protein variants. We describe here the impact of naturally occurring RBD mutations on the secretion of a recombinant Fc-tagged RBD protein expressed in HEK 293 cells. We show that mutation E484K of the B.1.351 variant interferes with the proper disulphide bond formation and folding of the recombinant protein, resulting in its retention into the endoplasmic reticulum (ER) and reduced protein secretion. Accumulation of the recombinant B.1.351 RBD-Fc fusion protein in the ER correlated with the upregulation of endogenous ER chaperones, suggestive of the unfolded protein response (UPR). Overexpression of the chaperone and protein disulphide isomerase PDIA2 further impaired protein secretion by altering disulphide bond formation and increasing ER retention. This work contributes to a better understanding of the challenges faced in producing mutant RBD proteins and can assist in the design of optimisation protocols.

By the emergence of SARS CoV-2 variants, many studies were developed to deal with it. The high transmissibility and mortality rate of some variants, in particular developing countries have caused the operation of simple diagnostic tests for genomic surveillance. In this study, we developed two assays of High Resolution Melting (HRM) and Probe-based RT-PCR as simple and inexpensive methods to identify the variants. We screened the mutations of del69–70, E484K, E484Q, D614G, L452R, and T478K in 100 cases from SARS-COV-2 positive patients in Kurdistan- Iran population. In general, the result of the two methods overlapped each other, nevertheless, we suggested HRM results be confirmed with a standard assay (Whole-Genome Sequencing). This work indicated that HRM as the rapid and inexpensive method could identify and categorize the variants of SARS CoV-2 and reduce the costs for carrying out sequencing. • High Resolution Melting (HRM) can be considered as reliable methods in classifying SARS CoV-2 variants. • suspect new mutations in the SARS CoV-2 genome is relatively provided by HRM technique. • Delta variant was the major variant of SARS CoV-2 in the fifth peak of Sanandaj, Iran population. [ABSTRACT FROM AUTHOR]

• The E484K mutation in B.1 + L249S+E484K appears not to affect the viral titer. • Sensitivity of lineages without E484K mutation to neutralizing antibodies did not change. • B.1 + L249S+E484K lineage shows a reduction in its neutralizing capacity. The E484K mutation at the SARS-CoV-2 Spike protein emerged independently in different variants around the world and has been widely associated with immune escape from neutralizing antibodies generated during previous infection or vaccination. In this work, the B.1 + L249S+E484K lineage was isolated along with A.1, B.1.420, and B.1.111 SARS-CoV-2 lineages without the E484K mutation and the neutralizing titer of convalescent sera was compared using microneutralization assays. While no significant differences in the neutralizing antibody titers were found between A.1 and B.lineages without the E484K mutation, the neutralizing titers against B.1 + L249S+E484K were 1.5, 1.9, 2.1, and 1.3-fold lower than against A.1, B.1.420, B.1.111-I, and B.1.111-II, respectively. However, molecular epidemiological data indicate that there is no increase in the transmissibility rate associated with this new lineage. This study supports the capability of new variants with the E484K mutation to be resistant to neutralization by humoral immunity, and therefore the need to intensify surveillance programs to determine if these lineages represent a risk for public health. [ABSTRACT FROM AUTHOR]

Several factors may account for the recent increased spread of the SARS-CoV-2 Delta sub-lineage AY.4.2 in the United Kingdom, Romania, Poland, and Denmark. We evaluated the sensitivity of AY.4.2 to neutralisation by sera from 30 Comirnaty (BNT162b2 mRNA) vaccine recipients in Denmark in November 2021. AY.4.2 neutralisation was comparable to other circulating Delta lineages or sub-lineages. Conversely, the less prevalent B.1.617.2 with E484K showed a significant more than 4-fold reduction in neutralisation that warrants surveillance of strains with the acquired E484K mutation.

With the emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants and the acquisition of novel mutations in existing lineages, the need to implement methods capable of monitoring viral dynamics arises. We report the emergence and spread of a new SARS-CoV-2 variant within the B.1.575 lineage, containing the E484K mutation in the spike protein (named B.1.575.2), in a region in northern Spain in May and June 2021. SARS-CoV-2-positive samples with cycle threshold values of ≤30 were selected to screen for presumptive variants using the TaqPath coronavirus disease 2019 (COVID-19) reverse transcription (RT)-PCR kit and the TaqMan SARS-CoV-2 mutation panel. Confirmation of variants was performed by whole-genome sequencing. Of the 200 samples belonging to the B.1.575 lineage, 194 (97%) corresponded to the B.1.575.2 sublineage, which was related to the presence of the E484K mutation. Of 197 cases registered in the Global Initiative on Sharing Avian Influenza Data (GISAID) EpiCoV database as lineage B.1.575.2, 194 (99.5%) were identified in Pamplona, Spain. This report emphasizes the importance of complementing surveillance of SARS-CoV-2 with sequencing for the rapid control of emerging viral variants.

Background While public health strategies to contain the current coronavirus disease 2019 (COVID-19) pandemic are primarily focused on social distancing and isolation, emerging evidence suggest that in some regions social isolation failed to lead to further decrease in the number of COVID-19 deaths in the long run. This apparent paradox was particularly observed in the northern region of Brazil, in the state of Amazonas. We hypothesized that the emergence of new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mutations, leading to more transmissible and pathogenic variants, could explain the lack of further reductions in COVID-19 new cases and related deaths in some regions. Our objective is to determine if social isolation is associated with the emergence of new SARS-CoV-2 variants, particularly the P.1 lineage and E484K mutants, in Brazil and in the state of Amazonas. Materials and methods We assessed the prevailing SARS-CoV-2 genomes present in Brazil available on the GISAID (Global Initiative on Sharing All Influenza Data) database collected between June 1, 2020, and January 31, 2021. Data regarding demographics, lineage, and prevalence of P.1 lineage and E484K mutations were obtained. Social isolation was measured using the Social Isolation Index (SII), which quantifies the percentage of individuals that stayed within a distance of 450 meters from their homes on a given day, between February 1, 2020, and January 24, 2021. The number of daily COVID-19 deaths was obtained from the Brazilian Ministry of Health (OpenDataSUS, 2021) between March 12, 2020, and January 10, 2021. SII was correlated with the prevalence P.1 lineage and E484K mutations in the eight following weeks. All univariate associations were estimated using the Spearman Correlation Index. 3D surfaces were employed to reflect the relationship between time, social isolation, and prevalence of genomic variants simultaneously. Results A total of 773 and 77 samples were obtained in Brazil and in the Amazonas state, respectively. In the state of Amazonas, SII on a given week was positively, significantly, and moderately or strongly (r > 0.6) correlated with the prevalence of both P.1 lineage and other E484K variants in the six following weeks after the SII on a given week. Conversely, in overall Brazil, correlations between SII and P.1 lineage and E484K variants were weaker and shorter, or negative, respectively. When SII was below 40%, P.1 lineage or E484K variants were not detected in the following weeks. When SII was above 40%, apparently exponential positive correlations between SII and prevalence of both P.1 lineage and E484K variants were observed. Conclusion The results of this study indicate that SII above 40% is associated with the emergence of SARS-CoV-2 E484K variants and P.1 lineage in the state of Amazonas, which was not observed in overall Brazil., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2021, Zimerman et al.)