Article Ayurvedic medicines in alleviating the symptoms of SARS-CoV-2 omicron variant in North Indian population: a regional genomic study was published on April 17, 2023 in the journal Drug Metabolism and Personalized Therapy (volume 0, issue 0).

The emergence and establishment of SARS-CoV-2 variants of concern presented a major global public health crisis across the world. There were six waves of SARS-CoV-2 cases in Kenya that corresponded with the introduction and eventual dominance of the major SARS-COV-2 variants of concern, excepting the first 2 waves that were both wild-type virus. We estimate that more than 1000 SARS-CoV-2 introductions occurred in the two-year epidemic period (March 2020 – September 2022) and a total of 930 introductions were associated with variants of concern namely Beta (n=78), Alpha(n=108), Delta(n=239) and Omicron (n=505). A total of 29 introductions were associated with A.23.1 variant that circulated in high frequencies in Uganda and Rwanda. The actual number of introductions is likely to be higher than these conservative estimates due to limited genomic sequencing. Our data suggested that cryptic transmission was usually underway prior to the first real-time identification of a new variant, and that multiple introductions were responsible. Following emergence of each VOC and subsequent introduction, transmission patterns were associated with hotspots of transmission in Coast, Nairobi and Western Kenya and follows established land and air transport corridors. Understanding the introduction and dispersal of major circulating variants and identifying the sources of new introductions is important to inform public health control strategies within Kenya and the larger East-African region. Border control and case finding reactive to new variants is unlikely to be a successful control strategy.

Despite unprecedented global sequencing and surveillance of SARS-CoV-2, timely identification of the emergence and spread of novel variants of concern (VoCs) remains a challenge. Several million raw genome sequencing runs are now publicly available. We sought to survey these datasets for intrahost variation to study emerging mutations of concern. We developed iSKIM (“intrahost SARS-CoV-2 k-mer identification method”) to relatively quickly and efficiently screen the many SARS-CoV-2 datasets to identify intrahost mutations belonging to lineages of concern. Certain mutations surged in frequency as intrahost minor variants just prior to, or while lineages of concern arose. The Spike N501Y change common to several VoCs was found as a minor variant in 834 samples as early as October 2020. This coincides with the timing of the first detected samples with this mutation in the Alpha/B.1.1.7 and Beta/B.1.351 lineages. Using iSKIM, we also found that Spike L452R was detected as an intrahost minor variant as early as September 2020, prior to the observed rise of the Epsilon/B.1.429/B.1.427 lineages in late 2020. iSKIM rapidly screens for mutations of interest in raw data, prior to genome assembly, and can be used to detect increases in intrahost variants, potentially providing an early indication of novel variant spread.

La enfermedad por coronavirus 2019 (COVID-19) ha generado un impacto a gran escala en la salud pública mundial debido a su rápida propagación y a su alta capacidad de contagio, adaptación y evolución. En esta revisión se describen las diferencias entre mutaciones, variantes, linajes y cepas de Coronavirus del Síndrome Respiratorio Agudo Severo 2 (SARS-CoV-2); se listan las principales mutaciones presentes en las variantes de interés (VOI por sus siglas en inglés) y variantes de preocupación (VOC por sus siglas en inglés) de SARS-CoV-2 y su distribución geográfica; y finalmente, se analiza la implicación que tienen las nuevas variantes sobre la efectividad de las vacunas, evidenciando la importancia de la vigilancia genómica de SARS-CoV-2 en la era post vacunación.

The continuous emergence of new SARS-CoV-2 variants required rapid and reliable diagnostic methods for early detection and monitoring of the spread of the virus, especially in low-resource countries where whole genome sequencing is not available. We aimed to evaluate and compare the performance of two different RT-qPCR screening assays for the detection of B.1.617 lineage mutations. A total of 85 SARS-CoV-2 positive samples were collected between 9^th August and 10 September 2021 and screened by two mutation-specific RT-qPCR assays for simultaneous detection of B.1.617.1 and B.1.617.2 lineage mutations. VIASURE Variant II PCR assay identified 2 Delta variant-specific mutations (L452R, and P681 R) in 80% of tested samples, while the PKamp™ Variant Detect™ assay was only able to detect one Delta variant specific mutation (L452R) in 75% of tested samples. This is the first report to show the Delta variant as the cause of the third wave in Libya. The use of multiplex RT-qPCR assays has allowed the identification of new variants for rapid screening. However, RT-qPCR results should be confirmed by whole genome sequencing of SARS-COV-2.

Given the challenges that fast-changing SARS-CoV-2 variants have caused in terms of rapid spread and reduced vaccine efficacy, a rapid and cost-effective assay that can detect new and emerging variants is greatly needed worldwide. We have successfully applied the xenonucleic acid-based molecular-clamping technology to develop a multiplex RT-qPCR assay for SARS-CoV-2 multivariant detection. The assay was tested on 649 nasopharyngeal swab samples that were collected from California and Ohio. The assay was able to correctly identify all 36 Delta variant samples as it accurately detected D614G, T478K and L452R mutations. In addition, the assay was able to correctly identify all 34 Omicron samples by detecting K417N, T478K, N501Y and D614G mutations. This technique reliably detects a variety of variants and has an analytical sensitivity of 100 copies/mL. In conclusion, this novel assay can serve as a rapid and cost-effective tool to facilitate large-scale detection of SARS-CoV-2 variants.

SARS-CoV-2 is the causative agent of COVID-19. The virus has spread across the planet, causing a global pandemic.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected more than 529 million people, and today the world is facing different mutant strains of the virus, leading to increased morbidity rates, fatality rates, and surfacing re-infections. Various therapies, such as prophylactic treatments, repurposed drug treatments, convalescent plasma, and polyclonal antibody therapy have been developed to help combat the coronavirus disease 2019 (COVID-19). This review article provides insights into the basic aspects of monoclonal antibodies (mAbs) for the therapy of COVID-19, as well as its advancement in terms of clinical trial and current approval status. Monoclonal antibodies represents the most effective and viable therapy and/or prophylaxis option against COVID-19, and have shown a reduction of the viral load, as well as lowering hospitalizations and death rates. In different countries, various mAbs are undergoing different phases of clinical trials, with a few of them having entered phases III and IV. Due to the soaring number of cases worldwide, the FDA has given emergency approval for the mAb combinations bamlanivimab with etesevimab and casirivimab with imdevimab.

SARS-CoV-2 is an RNA coronavirus responsible for Acute Respiratory Syndrome (COVID-19). In January 2021, the re-occurrence of COVID-19 infection was at its peak, considered the second wave of epidemics. In the initial stage, it was considered a double mutant strain due to two significant mutations observed in their Spike protein (E484Q and L452R). Although it was first detected in India later on, it was spread to several countries worldwide, causing high fatality due to this strain. In the present study, we investigated the spreading of B.1.617 strain worldwide through 822 genome sequences submitted in GISAID on 21 April 2021. All genome sequences were analyzed for variations in genome sequences based on their effects due to changes in nucleotides. At Allele frequency 0.05, there were a total of 47 variations in ORF1ab, 22 in Spike protein gene, 6 variations in N gene, 5 in ORF8 and M gene, four mutations in Orf7a, and one nucleotide substitution observed for ORF3a, ORF6 and ORF7b gene. The clustering for similar mutations mentioned B.1.617 sub-lineages. The outcome of this study established relative occurrence and spread worldwide. The study’s finding represented that “double mutant” strain is not only spread through traveling but it is also observed to evolve naturally with different mutations observed in B.1.617 lineage. The information extracted from the study helps to understand viral evolution and genome variations of B.1.617 lineage. The results support the need of separating B.1.617 into sub-lineages.

Enhanced viral transmission and escape from vaccine–elicited neutralizing antibodies drive worldwide spread of SARS-CoV-2 variants and promote disease progression. However, the impact of specific spike mutations that are carried by different viral variants on viral infectivity and neutralization sensitivity has not been completely defined. Here, we use pseudoviruses to assess the contribution of spike mutations within the Receptor Binding Domain (RBD) and the Furin Cleavage Site (FCS), and appear in circulating viral variants, on viral infectivity and neutralization potential against sera that was drawn from fully vaccinated individuals. Our functional analysis demonstrates that single, P681H, P681R or A701V–FCS mutations do not play a role in viral infectivity and neutralization potential. However, when in conjunction with the RBD–N501Y mutation, viral infectivity is enhanced. Similarly, combining the E484K–RBD mutation to the spike that carries FCS mutations reduces neutralization sensitivity with no effects on viral infectivity. Employing a similar approach onto the spike from Delta or Lota SARS-CoV-2 variants further reveals that specific RBD mutations affect neutralization sensitivity or viral infectivity differently. Our results validate the efficacy of the Pfizer third dose vaccine against Delta and Lota SARS-CoV-2 variants, and outline the significance of distinct RBD mutations in promoting viral infectivity and neutralization sensitivity to post–vaccination sera.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent responsible for the coronavirus disease 2019 (COVID-19). The high rate of mutation of this virus is associated with a quick emergence of new viral variants that have been rapidly spreading worldwide. Several mutations have been documented in the receptor-binding domain (RBD) of the viral spike protein that increases the interaction between SARS-CoV-2 and its cellular receptor, the angiotensin-converting enzyme 2 (ACE2). Mutations in the spike can increase the viral spread rate, disease severity, and the ability of the virus to evade either the immune protective responses, monoclonal antibody treatments, or the efficacy of current licensed vaccines. This review aimed to highlight the functional virus classification used by the World Health Organization (WHO), Phylogenetic Assignment of Named Global Outbreak (PANGO), Global Initiative on Sharing All Influenza Data (GISAID), and Nextstrain, an open-source project to harness the scientific and public health potential of pathogen genome data, the chronological emergence of viral variants of concern (VOCs) and variants of interest (VOIs), the major findings related to the rate of spread, and the mutations in the spike protein that are involved in the evasion of the host immune responses elicited by prior SARS-CoV-2 infections and by the protection induced by vaccination.

The SARS-CoV-2 Delta variant is currently the dominant circulating strain in the world. Uncovering the structural basis of the enhanced transmission and altered immune sensitivity of Delta is particularly important. Here we present cryo-EM structures revealing two conformational states of Delta spike and S/ACE2 complex in four states. Our cryo-EM analysis suggests that RBD destabilizations lead to population shift towards the more RBD-up and S1 destabilized fusion-prone state, beneficial for engagement with ACE2 and shedding of S1. Noteworthy, we find the Delta T478K substitution plays a vital role in stabilizing and reshaping the RBM loop^473-490, enhancing interaction with ACE2. Collectively, increased propensity for more RBD-up states and the affinity-enhancing T478K substitution together contribute to increased ACE2 binding, providing structural basis of rapid spread of Delta. Moreover, we identify a previously generated MAb 8D3 as a cross-variant broadly neutralizing antibody and reveal that 8D3 binding induces a large K478 side-chain orientation change, suggesting 8D3 may use an “induced-fit” mechanism to tolerate Delta T478K mutation. We also find that all five RBD-targeting MAbs tested remain effective on Delta, suggesting that Delta well preserves the neutralizing antigenic landscape in RBD. Our findings shed new lights on the pathogenicity and antibody neutralization of Delta.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in 2019 has led to the development of a large number of vaccines, several of which are now approved for use in humans. Understanding vaccine-elicited antibody responses against emerging SARS-CoV-2 variants of concern (VOC) in real time is key to inform public health policies. Serum neutralizing antibody titers are the current best correlate of protection from SARS-CoV-2 challenge in non-human primates and a key metric to understand immune evasion of VOC. We report that vaccinated BALB/c mice do not recapitulate faithfully the breadth and potency of neutralizing antibody responses against VOC, as compared to non-human primates or humans, suggesting caution should be exercised when interpreting data for this animal model.

The Delta and Kappa variants of SARS-CoV-2 co-emerged in India in late 2020, with the Delta variant underlying the resurgence of COVID-19, even in countries with high vaccination rates. In this study, we assess structural and biochemical aspects of viral fitness for these two variants using cryo-electron microscopy (cryo-EM), ACE2-binding and antibody neutralization analyses. Both variants demonstrate escape of antibodies targeting the N-terminal domain, an important immune hotspot for neutralizing epitopes. Compared to wild-type and Kappa lineages, Delta variant spike proteins show modest increase in ACE2 affinity, likely due to enhanced electrostatic complementarity at the RBD-ACE2 interface, which we characterize by cryo-EM. Unexpectedly, Kappa variant spike trimers form a structural head-to-head dimer-of-trimers assembly, which we demonstrate is a result of the E484Q mutation and with unknown biological implications. The combination of increased antibody escape and enhanced ACE2 binding provides an explanation, in part, for the rapid global dominance of the Delta variant.

Repurposing of currently available drugs is a valuable strategy to tackle the consequences of COVID-19. Recently, several studies have investigated the effect of psychoactive drugs on SARS-CoV-2 in cell culture models as well as in clinical practice. Our aim was to expand these studies and test some of these compounds against newly emerged variants. Several antidepressants and antipsychotic drugs with different primary mechanisms of action were tested in ACE2/TMPRSS2-expressing human embryonic kidney cells against the infection by SARS-CoV-2 spike protein-dependent pseudoviruses. Some of these compounds were also tested in human lung epithelial cell line, Calu-1, against the first wave (B.1) lineage of SARS-CoV-2 and the variants of concern, B.1.1.7, B.1.351, and B.1.617.2. Several clinically used antidepressants, including fluoxetine, citalopram, reboxetine, imipramine, as well as antipsychotic compounds chlorpromazine, flupenthixol, and pimozide inhibited the infection by pseudotyped viruses with minimal effects on cell viability. The antiviral action of several of these drugs was verified in Calu-1 cells against the B.1 lineage of SARS-CoV-2. By contrast, the anticonvulsant carbamazepine, and novel antidepressants ketamine, known as anesthetic at high doses, and its derivatives as well as MAO and phosphodiesterase inhibitors phenelzine and rolipram, respectively, showed no activity in the pseudovirus model. Furthermore, fluoxetine remained effective against pseudoviruses with common receptor binding domain mutations, N501Y, K417N, and E484K, as well as B.1.1.7 (alpha), B.1.351 (beta), and B.1.617.2 (delta) variants of SARS-CoV-2. Our study confirms previous data and extends information on the repurposing of these drugs to counteract SARS-CoV-2 infection including different variants of concern, however, extensive clinical studies must be performed to confirm our in vitro findings.

The rapid emergence of SARS-CoV-2 variants is fueling the recent waves of the COVID-19 pandemic. Here, we assessed ACE2 binding and antigenicity of Mu (B.1.621) and A.2.5 Spikes. Both these variants carry some mutations shared by other emerging variants. Some of the pivotal mutations such as N501Y and E484K in the receptor-binding domain (RBD) detected in B.1.1.7 (Alpha), B.1.351 (Beta) and P.1 (Gamma) are now present within the Mu variant. Similarly, the L452R mutation of B.1.617.2 (Delta) variant is present in A.2.5. In this study, we observed that these Spike variants bound better to the ACE2 receptor in a temperature-dependent manner. Pseudoviral particles bearing the Spike of Mu were similarly neutralized by plasma from vaccinated individuals than those carrying the Beta (B.1.351) and Delta (B.1.617.2) Spikes. Altogether, our results indicate the importance of measuring critical parameters such as ACE2 interaction, plasma recognition and neutralization ability of each emerging variant.

The rapid spread of SARS-CoV-2 variants poses a constant threat of escape from monoclonal antibody and vaccine countermeasures. Mutations in the ACE2 receptor binding site on the surface S protein have been shown to disrupt antibody binding and prevent viral neutralization. Here, we use a directed evolution-based approach to engineer three neutralizing antibodies for enhanced binding to S protein. The engineered antibodies showed increased in vitro functional activity in terms of neutralization potency and/or breadth of neutralization against viral variants. Deep mutational scanning revealed that higher binding affinity reduced the total number of viral escape mutations. Studies in the Syrian hamster model showed two examples where the affinity matured antibody provided superior protection compared to the parental antibody. These data suggest that monoclonal antibodies for anti-viral indications could benefit from in vitro affinity maturation to reduce viral escape pathways and appropriate affinity maturation in vaccine immunization could help resist viral variation.

How the Delta variant evades defenses: In the course of the COVID-19 epidemic, variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continue to emerge, some of which evade immunity or increase transmission. In late 2020, the Delta and Kappa variants were detected, and the Delta variant became globally dominant by June 2021. McCallum et al . show that vaccine-elicited serum-neutralizing activity is reduced against these variants. Based on biochemistry and structural studies, the authors show that mutations in the domain that binds the ACE2 receptor abrogate binding to some monoclonal antibodies but do not improve ACE2 binding, suggesting that they emerged to escape immune recognition. Remodeling of the N-terminal domain allows the variants to escape recognition by most neutralizing antibodies that target it. The work could guide the development of next-generation vaccines and antibody therapies. —VV

The emergence of SARS-CoV-2 Kappa and Beta variants with enhanced transmissibility and resistance to neutralizing antibodies has created new challenges for the control of the ongoing COVID-19 pandemic. Understanding the structural nature of Kappa and Beta spike (S) proteins and their association with ACE2 is of significant importance. Here we present two cryo-EM structures for each of the Kappa and Beta spikes in the open and open-prone transition states. Compared with wild-type (WT) or G614 spikes, the two variant spikes appear more untwisted/open especially for Beta, and display a considerable population shift towards the open state as well as more pronounced conformational dynamics. Moreover, we capture four conformational states of the S-trimer/ACE2 complex for each of the two variants, revealing an enlarged conformational landscape for the Kappa and Beta S-ACE2 complexes and pronounced population shift towards the three RBDs up conformation. These results implicate that the mutations in Kappa and Beta may modify the kinetics of receptor binding and viral fusion to improve virus fitness. Combined with biochemical analysis, our structural study shows that the two variants are enabled to efficiently interact with ACE2 receptor despite their sensitive ACE2 binding surface is modified to escape recognition by some potent neutralizing MAbs. Our findings shed new light on the pathogenicity and immune evasion mechanism of the Beta and Kappa variants.

In order to evaluate the decline in antibody levels and the impact of vaccination on the spread of the epidemic, we establish COVID-19 dynamic models that consider the decline in antibody levels and the effects of vaccination, and retrospectively evaluate the epidemic situation in England. Based on the epidemic data in England from September 1 to October 31, 2020, considering the continuous decline in the antibody level of COVID-19 recovers, an improved SEIR infectious disease dynamics model that considers the reinfection of recovers due to the decline in antibody levels is established. The kinetic parameters of the SEIR model are obtained by fitting. On this basis, a SEIRV infectious disease dynamic model with vaccination is established to study the impact of different vaccination rates and vaccine failure rates on the development of the epidemic in England. We obtain the lower the vaccine failure rate, the fewer new cases. When the vaccination rate is fixed at 0.005 (equivalent to 250000 people vaccinated every day), the peak of the epidemic will decrease with the decrease of vaccine failure rate. The peak value when the failure rate is 0.001 is 81.4% lower than the peak value when the failure rate is 0.01, and the peak value when the failure rate is 0.01 is 89.5% lower than the peak value when the failure rate is 0.02. When the failure rate is less than 0.01, the peak time will advance with the decrease of failure rate; when the failure rate is greater than 0.01, the peak time will be delayed with the decrease of failure rate; when the failure rate is 0.01, the peak time is 528 days later than that when the failure rate is 0.001 and 295 days later than that when the failure rate is 0.05. On the 60th day of vaccination, the vaccine failure rate of 0.002 decreases the number of cases by 5.8% compared with the vaccine failure rate of 0.01; on the 70th day of vaccination, the vaccine failure rate of 0.002 reduces the number of cases by 9.1% compared with the vaccine failure rate of 0.01. Therefore, with the extension of time, the vaccine with low failure rate has a more obvious effect on reducing the number of cases than the vaccine with high failure rate. When the vaccine failure rate is fixed at 0.005, we study the impact of different vaccination rates on the spread of the epidemic in England, the result shows that the peak of epidemic situation decreases with the increase of vaccination rate, and the peak time advance with the increase of vaccination rate, when the vaccination rate is 0.025, the peak decreases by 74.8% and the peak time was 114 days earlier than that when the vaccination rate is 0.005. Therefore, the higher the vaccine efficiency and vaccination rate, the lower the peak of the epidemic. On the basis of improving the effectiveness of vaccines, increasing the vaccination rate is of practical significance for controlling the spread of the epidemic.

The recent emergence of novel SARS-CoV-2 variants has threatened the efforts to contain the COVID-19 pandemic. The emergence of these “variants of concern” has increased immune escape and has supplanted the ancestral strains. The novel variants harbored by the B.1.617 lineage (kappa and delta) carry mutations within the receptor-binding domain of spike (S) protein (L452R + E484Q and L452R + T478K), the region binding to the host receptor. The double mutations carried by these novel variants are primarily responsible for an upsurge number of COVID-19 cases in India. In this study, we thoroughly investigated the impact of these double mutations on the binding capability to the human host receptor. We performed several structural analyses and found that the studied double mutations increase the binding affinity of the spike protein to the human host receptor (ACE2). Furthermore, our study showed that these double mutants might be a dominant contributor enhancing the receptor-binding affinity of SARS-CoV-2 and consequently making it more stable. We also investigated the impact of these mutations on the binding affinity of two monoclonal antibodies (Abs) (2-15 and LY-CoV555) and found that the presence of the double mutations also hinders its binding with the studied Abs. The principal component analysis, free energy landscape, intermolecular interaction, and other investigations provided a deeper structural insight to better understand the molecular mechanism responsible for increased viral transmissibility of these variants.

The COVID-19 pandemic is a global challenge that impacted 200+ countries. India ranks in the second and third positions in terms of number of reported cases and deaths. Being a populous country with densely packed cities, SARS-CoV-2 spread exponentially. India sequenced ≈0.14% isolates from confirmed cases for pandemic surveillance and contributed ≈1.58% of complete genomes sequenced globally. This study was designed to map the circulating lineage diversity and to understand the evolution of SARS-CoV-2 in India using comparative genomics and population genetics approaches. Despite varied sequencing coverage across Indian States and Union Territories, isolates belonging to variants of concern (VoC) and variants of interest (VoI) circulated, persisted, and diversified during the first seventeen months of the pandemic. Delta and Kappa lineages emerged in India and spread globally. The phylogenetic tree shows lineage-wise monophyletic clusters of VoCs/VoIs and diversified tree topologies for non-VoC/VoI lineages designated as ‘Others’ in this study. Evolutionary dynamics analyses substantiate a lack of spatio-temporal clustering, which is indicative of multiple global and local introductions. Sites under positive selection and significant variations in spike protein corroborate with the constellation of mutations to be monitored for VoC/VoI as well as substitutions that are characteristic of functions with implications in virus–host interactions, differential glycosylation, immune evasion, and escape from neutralization.

Background: After the first detection in November 2019, SARS-CoV-2 has spread rapidly over the continents and started the pandemic of the millennium. In addition to several novels and repurposed monoclonal antibodies (mAbs) as a therapeutic option against COVID-19, scientists from across the world have developed several candidate vaccines, developed mainly targeting the Wuhan strain, with very promising results to combat this pandemic. Unfortunately like any RNA viruses, SARS CoV-2 has also gone through the accumulation of hundreds and thousands of mutations in their genome lead to the development of several variants of concerns (VOC) and variants of interests (VOI), resulting in increased transmissibility and virulence of the virus, along with their capacity to escape cross-protection. Seemingly, the main hindrance of containing this pandemic right now is the effectiveness of currently available vaccines and mAbs against newly emerging variants. Therefore, it is important to monitor variants epidemiology, transmission dynamics, clinical characteristics, as well as their immune evasion capacity to implement appropriate vaccine strategy and other containment measures. Body: In this review, we tried to focus on variants characteristics and to what extent they can escape immunity, provided by both available vaccinated sera and convalescent sera. A stringent literature review was performed using various databases, mentioned in the methodology portion. The current geographical distribution of these variants of SARS CoV-2 has been presented using a heat map. Findings from published articles comparing these variants, in terms of genome epidemiology, transmissibility, viral load dynamics, and association with different waves have been described briefly. Due strength was given while describing variants neutralization potency against current vaccines, mAbs, and also against convalescent sera. Data from both clinical trials and in vitro/ex-vivo studies have been discussed here. Comparative findings from several articles were brought into one concise paper. After careful reviewing of all the available data, it was clear that, without hesitation, we should strengthen our vaccination strategy, because the severity of COVID 19 is reasonably lower, irrespective of variants and vaccine used. Conclusion: We hope that many falsified myths and beliefs regarding vaccine immunity and emerging variants will be clarified in light of this available evidence, which we summarized in our paper.

SARS-CoV-2 genome surveillance projects provide a good measure of transmission and monitor the circulating SARS-CoV-2 variants at regional and global scales. Iran is one of the most affected countries still involved with the virus circulating in at least five significant disease waves, as of September 2021. Complete genome sequencing of 50 viral isolates in an early phase of outbreak in Iran, shed light on the origins and circulating lineages at that time. As part of a genomic surveillance program, we provided an additional 319 complete genomes from October 2020 onwards. The current study is the report of complete SARS-CoV-2 genome sequences of Iran in the March 2020-May 2021 time interval. We aimed to characterize the genetic diversity of SARS-CoV-2 in Iran over one year. Overall, 35 different lineages and 8 clades were detected. Temporal dynamics of the prominent SARS-CoV-2 clades/lineages circulating in Iran is comparable to the global perspective and introduces the 19A clade (B.4) dominating the first disease wave, followed by 20A (B.1.36), 20B (B.1.1.413), 20I (B.1.1.7) clades, dominating second, third and fourth disease waves, respectively. We observed a mixture of circulating 20A (B.1.36), 20B (B.1.1.413), 20I (B.1.1.7) clades in winter 2021, paralleled in a diminishing manner for 20A/20B and a growing rise for 20I, eventually prompting the 4^th outbreak peak. Furthermore, our study provides evidence on the entry of the Delta variant in April 2021, leading to the 5^th disease wave in summer 2021. Three lineages are highlighted as hallmarks of SARS-CoV-2 outbreak in Iran; B4, dominating early periods of the epidemic, B.1.1.413 (specific B.1.1 lineage carrying a combination of [D138Y-S477N-D614G] spike mutations) in October 2020-February 2021, and the co-occurrence of [I100T-L699I] spike mutations in half of B.1.1.7 sequences mediating the fourth peak. Continuous monthly monitoring of SARS-CoV-2 genome mutations led to the detection of 1577 distinct nucleotide mutations, in which the top recurrent mutations were D614G, P323L, R203K/G204R, 3037C>T, and 241C>T; the renowned combination of mutations in G and GH clades. The most frequent spike mutation is D614G followed by 13 other frequent mutations based on the prominent circulating lineages; B.1.1.7 (H69_V70del, Y144del, N501Y, A570D, P681H, T716I, S982A, D1118H, I100T, and L699I), B.1.1.413 (D138Y, S477N) and B.1.36 (I210del). In brief, mutation surveillance in this study provided a real-time comprehensive picture of the SARS-CoV-2 mutation profile in Iran, which is beneficial for evaluating the magnitude of the epidemic and assessment of vaccine and therapeutic efficiency in this population.

Background: Novel coronavirus SARS-CoV2 is evolving continuously with emergence of several variants of increasing transmission capabilities and pandemic potential. Generation of variants occurs through accumulation of mutations due to the RNA nature of viral genome, which is further enhanced by variable selection pressures of this ongoing pandemic. COVID-19 presentations of SARS-CoV2 are mainly pulmonary manifestations with or without mild gastrointestinal (GI) and hepatic symptoms. However, the virus has evolved beyond pulmonary manifestations to multisystem disorder due to systemic inflammation and cytokine storm. Definitive cause of acute or late onset of inflammation, infection in various organs, and host response to emerging variants lacks clarity and needs elucidation. Several studies have reported underlying diseases including diabetes, hypertension, obesity, cardio- and cerebrovascular disorders, and immunocompromised conditions as significant risk factors for severe form of COVID-19. Pre-existing liver and GI diseases are also highly predominant in the population, which can alter COVID-19 outcome due to altered immune status and host response. We aim to review the emerging variants of SARS-CoV2 and host response in patients with pre-existing liver and GI diseases.Methods: In this review, we have elucidated the emergence and characteristic features of new SARS-CoV2 variants, mechanisms of infection and host immune response, GI and hepatic manifestation with radiologic features of COVID-19, and outcomes in pre-existing liver and GI diseases.Key Findings: Emerging variants of concern (VOC) have shown increased transmissibility and virulence with severe COVID-19 presentation and mortality. There is a drastic swift of variants from the first wave to the next wave of infections with predominated major VOC including alpha (B.1.1.7, UK), beta (B.1.351, South Africa), gamma (B.1.1.28.1, Brazil), and delta (B1.1.617, India) variants. The mutations in the spike protein of VOC are implicated for increased receptor binding (N501Y, P681R) and immune escape (L452R, E484K/Q, T478K/R) to host response. Pre-existing liver and GI diseases not only have altered tissue expression and distribution of viral entry ACE2 receptor but also host protease TMPRSS2, which is required for both spike protein binding and cleavage to initiate infection. Altered immune status due to pre-existing conditions results in delayed virus clearance or prolonged viremia. Even though GI and hepatic manifestations of SARS-CoV2 are less severe, the detection of virus in patient’s stool indicates GI tropism, replication, and shedding from the GI tract. COVID-19-induced liver injury, acute hepatic decompensation, and incidences of acute-on-chronic liver failure may change the disease outcomes.Conclusions: The changes in the spike protein of emerging variants, immunomodulation by viral proteins, and altered expression of host viral entry receptor in pre-existing diseases are the key determinants of host response to SARS-CoV2 and its disease outcome.

Severe COVID-19 is characterized by lung abnormalities, including the presence of syncytial pneumocytes. Syncytia form when SARS-CoV-2 spike protein expressed on the surface of infected cells interacts with the ACE2 receptor on neighbouring cells. The syncytia forming potential of spike variant proteins remain poorly characterized. Here, we first assessed Alpha (B.1.1.7) and Beta (B.1.351) spread and fusion in cell cultures, compared to the ancestral D614G strain. Alpha and Beta replicated similarly to D614G strain in Vero, Caco-2, Calu-3 and primary airway cells. However, Alpha and Beta formed larger and more numerous syncytia. Variant spike proteins displayed higher ACE2 affinity compared to D614G. Alpha, Beta and D614G fusion was similarly inhibited by interferon induced transmembrane proteins (IFITMs). Individual mutations present in Alpha and Beta spikes modified fusogenicity, binding to ACE2 or recognition by monoclonal antibodies. We further show that Delta spike also triggers faster fusion relative to D614G. Thus, SARS-CoV-2 emerging variants display enhanced syncytia formation.

Bispecific antibodies targeting multiple regions of the SARS-CoV-2 spike protein comparably neutralize variants of concern and wild-type virus.

The evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus leads to new variants that warrant timely epidemiological characterization. Here we use the dense genomic surveillance data generated by the COVID-19 Genomics UK Consortium to reconstruct the dynamics of 71 different lineages in each of 315 English local authorities between September 2020 and June 2021. This analysis reveals a series of subepidemics that peaked in early autumn 2020, followed by a jump in transmissibility of the B.1.1.7/Alpha lineage. The Alpha variant grew when other lineages declined during the second national lockdown and regionally tiered restrictions between November and December 2020. A third more stringent national lockdown suppressed the Alpha variant and eliminated nearly all other lineages in early 2021. Yet a series of variants (most of which contained the spike E484K mutation) defied these trends and persisted at moderately increasing proportions. However, by accounting for sustained introductions, we found that the transmissibility of these variants is unlikely to have exceeded the transmissibility of the Alpha variant. Finally, B.1.617.2/Delta was repeatedly introduced in England and grew rapidly in early summer 2021, constituting approximately 98% of sampled SARS-CoV-2 genomes on 26 June 2021.

SARS-CoV-2 variants rapid emergence has posed critical challenge of higher transmission and immune escape causing serious threats to control the pandemic. The present study was carried out in confirmed cases of SARS-CoV-2 patients to elucidate the prevalence of SARS-CoV-2 variant strain. We performed RT-PCR using extracted RNA from the nasopharyngeal swabs of suspected Covid-19 patients. Confirmed positive cases with CT<25 were subjected to whole-genome sequencing to track the prevalence of the virus in the Malwa region of Punjab. The presence of B.1, B.1.1.7, B.1.351, B.1.617.1, B.1.617.2, AY.1 and other unidentified variants of SARS-CoV-2 was found in the studied population. Among all the variants, B.1.1.7 (UK variant) and B.1.617.2 (delta-Indian variant) was found to be the most dominant variant in the population and was found majorly in Patiala followed by Ludhiana, SBS Nagar, Mansa and Sangrur. In addition to this, sequencing results also observed that the dominant trait was more prevalent in male population and age group 21-40 years. The B.1.1.7 and B.1.617.2 variant of SARS-CoV-2 is replacing the wild type (Wuhan Strain) and emerging as the dominant variant in Punjab.

SARS CoV-2 variants raise significant concerns due to their ability to cause vaccine breakthrough infections. Here, we sequence-characterized the spike gene, isolated from a breakthrough infection, that corresponded to B.1.617.3 lineage. Delineating the functional impact of spike mutations using reporter pseudoviruses (PV) revealed that N-terminal domain (NTD)-specific E156G/Δ157-158 contributed to increased infectivity and reduced sensitivity to ChAdOx1 nCoV-19 vaccine (Covishield™)-elicited neutralizing antibodies. A six-nucleotide deletion (467-472) in the spike coding region introduced this change in the NTD. We confirmed the presence of E156G/Δ157-158 in the RT-PCR-positive cases concurrently screened, in addition to other circulating spike (S1) mutations like T19R, T95I, L452R, E484Q, and D614G. Notably, E156G/Δ157-158 was present in more than 85% of the sequences reported from the USA, UK, and India in August 2021. The spike PV bearing combination of E156G/Δ157-158 and L452R further promoted infectivity and conferred immune evasion. Additionally, increased cell-to-cell fusion was observed when spike harbored E156G/Δ157-158, L452R, and E484Q, suggesting a combinatorial effect of these mutations. Notwithstanding, the plasma from a recovered individual robustly inhibited mutant spike PV, indicating the increased breadth of neutralization post-recovery. Our data highlights the importance of spike NTD-specific changes in determining infectivity and immune escape of variants.

While vaccination programs against SARS-CoV-2 are globally ongoing, disparate strategies for the deployment of spike antigen show varying effectiveness. In order to explore this phenomenon, we sought to compare the early immune responses against AZD1222 and BNT162b2. SARS-CoV-2 seronegative participants received a single dose of either vaccine and were analyzed for immune cell, effector T cell and antibody dynamics. AZD1222 induced transient leukopenia and major changes among innate and adaptive subpopulations. Both vaccines induced spike protein specific effector T cells which were dominated by Th1 responses following AZD1222 vaccination. A significant reduction of anti-inflammatory T cells upon re-stimulation was also restricted to AZD1222 vaccinees. While IgM and IgG were the dominant isotypes elicited by AZD1222, BNT162b2 led to a significant production of IgG and IgA. Our results suggest that the strategy for spike antigen delivery impacts on how and to what extent immune priming against the main SARS-CoV-2 antigen proceeds.

The outbreak of COVID-19 has proven to be an unprecedented disaster for the whole world. The virus has inflicted billion of lives across the globe in all aspects—physically, psychologically, as well as socially. Compared to the previous strains of β-CoV genera- MERS and SARS, SARS-CoV-2 has significantly higher transmissibility and worst post-recovery implications. A frequent mutation in the initial SARS-CoV-2 strain has been a major cause of mortalities (approx. 3 million deaths) and uncontrolled virulence (approx. 1 billion positive cases). As far as clinical manifestations are concerned, this particular virus has exhibited deleterious impacts on systems other than the respiratory system (primary target organ), such as the brain, hematological system, liver, kidneys, endocrine system, etc. with no promising curatives to date. Lack of emergency treatments and shortage of life-saving drugs has promoted the repurposing of existing therapeutics along with the emergence of vaccines with the combined efforts of scientists and industrial experts in this short span. This review summarizes every detail on COVID-19 and emphasizes undermining the future approaches to minimize its prevalence to the remaining lives.

The surge of COVID-19 infection cases is spurred by emerging SARS-CoV-2 variants such as B.1.617. Here we report 38 cryo-EM structures, corresponding to the spike protein of the Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2) and Kappa (B.1.617.1) variants in different functional states with and without its receptor, ACE2. Mutations on the N-terminal domain not only alter the conformation of the highly antigenic supersite of the Delta variant, but also remodel the glycan shield by deleting or adding N-glycans of the Delta and Gamma variants, respectively. Substantially enhanced ACE2 binding was observed for all variants, whose mutations on the receptor binding domain modulate the electrostatics of the binding interfaces. Despite their abilities to escape host immunity, all variants can be potently neutralized by three unique antibodies.

B.1.617 is becoming a dominant Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) lineage worldwide with many sublineages, of which B.1.617.2 is designated as a variant of concern. The pathogenicity of B.1.617.2 (Delta) and B.1.617.3 lineage of SARS-CoV-2 was evaluated and compared with that of B.1, an early virus isolate with D614G mutation in a Syrian hamster model. Viral load, antibody response, and lung disease were studied. There was no significant difference in the virus shedding pattern among these variants. High levels of SARS-CoV-2 sub genomic RNA were detected in the respiratory tract of hamsters infected with the Delta variant for 14 days, which warrants further transmission studies. The Delta variant induced lung disease of moderate severity in about 40% of infected animals, which supports the attributed disease severity of the variant. Cross neutralizing antibodies were detected in animals infected with B.1, Delta, and B.1.617.3 variant, but neutralizing capacity was significantly lower with B.1.351 (Beta variant).

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) manifests a broad spectrum of clinical presentations, varying in severity from asymptomatic to mortality. As the viral infection spread, it evolved and developed into many variants of concern. Understanding the impact of mutations in the SARS-CoV-2 genome on the clinical phenotype and associated co-morbidities is important for treatment and preventionas the pandemic progresses. Based on the mild, moderate, and severe clinical phenotypes, we analyzed the possible association between both, the clinical sub-phenotypes and genomic mutations with respect to the severity and outcome of the patients. We found a significant association between the requirement of respiratory support and co-morbidities. We also identified six SARS-CoV-2 genome mutations that were significantly correlated with severity and mortality in our cohort. We examined structural alterations at the RNA and protein levels as a result of three of these mutations: A26194T, T28854T, and C25611A, present in the Orf3a and N protein. The RNA secondary structure change due to the above mutations can be one of the modulators of the disease outcome. Our findings highlight the importance of integrative analysis in which clinical and genetic components of the disease are co-analyzed. In combination with genomic surveillance, the clinical outcome-associated mutations could help identify individuals for priority medical support.

The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) outbreak in December 2019 has caused a global pandemic. The rapid mutation rate in the virus has created alarming situations worldwide and is being attributed to the false negativity in RT-PCR tests. It has also increased the chances of reinfection and immune escape. Recently various lineages namely, B.1.1.7 (Alpha), B.1.617.1 (Kappa), B.1.617.2 (Delta) and B.1.617.3 have caused rapid infection around the globe. To understand the biophysical perspective, we have performed molecular dynamic simulations of four different spikes (receptor binding domain)-hACE2 complexes, namely wildtype (WT), Alpha variant (N501Y spike mutant), Kappa (L452R, E484Q) and Delta (L452R, T478K), and compared their dynamics, binding energy and molecular interactions. Our results show that mutation has caused significant increase in the binding energy between the spike and hACE2 in Alpha and Kappa variants. In the case of Kappa and Delta variants, the mutations at L452R, T478K and E484Q increased the stability and intra-chain interactions in the spike protein, which may change the interaction ability of neutralizing antibodies to these spike variants. Further, we found that the Alpha variant had increased hydrogen interaction with Lys353 of hACE2 and more binding affinity in comparison to WT. The current study provides the biophysical basis for understanding the molecular mechanism and rationale behind the increase in the transmissivity and infectivity of the mutants compared to wild-type SARS-CoV-2.

Worldwide SARS-CoV-2 transmission leads to the recurrent emergence of variants, such as the recently described B.1.617.1 (kappa), B.1.617.2 (delta) and B.1.617.2+ (delta+). The B.1.617.2 (delta) variant of concern is causing a new wave of infections in many countries, mostly affecting unvaccinated individuals, and has become globally dominant. We show that these variants dampen the in vitro potency of vaccine-elicited serum neutralizing antibodies and provide a structural framework for describing the impact of individual mutations on immune evasion. Mutations in the B.1.617.1 (kappa) and B.1.617.2 (delta) spike glycoproteins abrogate recognition by several monoclonal antibodies via alteration of key antigenic sites, including an unexpected remodeling of the B.1.617.2 (delta) N-terminal domain. The binding affinity of the B.1.617.1 (kappa) and B.1.617.2 (delta) receptor-binding domain for ACE2 is comparable to the ancestral virus whereas B.1.617.2+ (delta+) exhibits markedly reduced affinity. We describe a previously uncharacterized class of N-terminal domain-directed human neutralizing monoclonal antibodies cross-reacting with several variants of concern, revealing a possible target for vaccine development.

SAB-185 is a fully human polyclonal anti-SARS-CoV-2 immunoglobulin produced from the plasma of transchromosomic bovines that are hyperimmunized with recombinant SARS-CoV-2 Wuhan-Hu-1 Spike protein. SAB-185 is being evaluated for efficacy in aphase 3 clinical trial. The World Health Organization (WHO) has identified multiple Variants-of-Concern and Variants-of-Interest (VOC/VOI) that have mutations in their Spike protein that appear to increase transmissibility and/or reduce the effectiveness of therapeutics and vaccines, among other parameters of concern. SAB-185 was evaluated using lentiviral-based pseudovirus assays performed in a BSL2 environment that incorporates stable or transient cell lines that express human angiotensin converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2). The results indicate that SAB-185 retained neutralization potency against multiple SARS-CoV-2 pseudovirus variants, including the Delta, Kappa, Lambda and Omicron variants, that have or are supplanting other VOC/VOI in many countries and regions around the world.

Background In Bogotá by August 1st, more than 27,000 COVID-19 deaths have been reported, while complete and partial vaccination coverage reached 30% and 37%, respectively. Although reported cases are decreasing, the potential impact of new variants is uncertain. Methods We used an agent-based model of COVID-19 calibrated to local data. Variants and vaccination strategies were included. We estimated the impact of vaccination and modelled scenarios of early and delayed introduction of the delta variant, along with changes in mobility, social contact, and vaccine uptake over the next months. Findings By mid-July, vaccination may have prevented 17,800 (95% CrI: 16,000 - 19,000) deaths in Bogotá. We found that delta could lead to a fourth wave of magnitude and timing dependent on social mixing, vaccination strategy, and delta dominance. In scenarios of early dominance of delta by mid-July, age prioritization and maintaining the interval between doses were important factors to avert deaths. However, if delta dominance occurred after mid-September, age prioritization would be less relevant, and the magnitude of a four wave would be smaller. In all scenarios, higher social mixing increased the magnitude of the fourth wave. Increasing vaccination rates from 50,000/day to 100,000/day reduced the impact of a fourth wave due to delta. Interpretation The magnitude and timing of a potential fourth wave in Bogotá caused by delta would depend on social mixing and the timing of dominance. Rapidly increasing vaccination coverage with non-delayed second doses could reduce the burden of a new wave. Funding NSF RAPID DEB 2027718. HERMES 50419. Medical Research Council. MR/R024855/1 Research in Context Evidence before this study The impact of vaccination strategies in the context of emerging SARS-CoV-2 variants and increasing social mixing in Colombia had not been previously evaluated through mathematical modelling. We searched PubMed for modelling studies using the terms “COVID-19 vaccine AND model AND variant AND Colombia” or “SARS-CoV-2 AND vaccine AND model AND variant AND Colombia” (From 2021/1/1 to 2021/07/31). We did not find studies addressing this question. However, we found a model describing the evolution of the epidemic in the country during the first year, and research on the emergence of alpha, gamma, and B.1.621 variants in Colombia. We extended a previous version of our SARS-CoV-2 agent-based model for Bogotá to include the potential effect of vaccination and variants. This model simulates transmission of SARS-CoV-2 based on daily activity patterns of a synthetic population, representing demographic and geographic characteristics of the total population of the city. Added value of this study First, our study provides a preliminary estimate of the impact of the vaccination program in Bogotá in terms of the number of deaths prevented. The second major finding is the indication that due to the introduction of the delta variant in the city, and based on the current knowledge of its biology, there is a risk of a fourth epidemic wave, whose time of occurrence and magnitude would depend mainly on three factors: when delta becomes dominant, the intensity of social contact, and vaccination roll-out strategy and coverage. Implications of all the available evidence We estimate that by mid-July, vaccination may have already prevented 17,800 (95% CrI: 16,000 - 19,000) deaths in Bogotá. The delta variant could become dominant and lead to a fourth wave later in the year, but its timing will depend on the date of introduction, social mixing patterns, and vaccination strategy. In all scenarios, higher social mixing is associated with a fourth wave of considerable magnitude. If an early delta introduction occurred (dominance by mid-July), a new wave may occur in August/September and in such case, age prioritization of vaccination and maintaining the 21-day interval between doses of the Pfizer-BioNTech BNT162b2 are more important. However, if introduction occurred one or two months later (with dominance by mid-August/September) a fourth wave would be of smaller magnitude, the age-prioritization is less relevant, but maintaining the dose scheme without postponement is more important. In all scenarios we found that increasing the vaccination rate from the current average of 50,000/day to 100,000/day reduces the impact of a potential fourth wave due to the delta variant. Our study indicates that given the possibility of a fourth wave in the city, it is necessary to continue maintaining adherence to non-pharmacological interventions, such as the use of face masks and physical distancing, to be cautious with the intensification of social activities, and that it is essential to increase the current pace of vaccinations to rapidly reach high vaccination coverage in the population of the city.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging respiratory virus responsible for the ongoing coronavirus disease 19 (COVID-19) pandemic. More than a year into this pandemic, the COVID-19 fatigue is still escalating and takes hold of the entire world population. Driven by the ongoing geographical expansion and upcoming mutations, the COVID-19 pandemic has taken a new shape in the form of emerging SARS-CoV-2 variants. These mutations in the viral spike (S) protein enhance the virulence of SARS-CoV-2 variants by improving viral infectivity, transmissibility, and immune evasion abilities. Such variants have resulted in cluster outbreaks and fresh infection waves in various parts of the world with increased disease severity and poor clinical outcomes. Hence, the variants of SARS-CoV-2 pose a threat to human health and public safety. This review enlists the most recent updates regarding the presently characterized variants of SARS-CoV-2 recognized by the global regulatory health authorities (WHO, CDC). Based on the slender literature on SARS-CoV-2 variants, we collate information on the biological implications of these mutations on virus pathology. We also shed light on the efficacy of therapeutics and COVID-19 vaccines against the emerging SARS-CoV-2 variants.

The seasonal nature in the outbreaks of respiratory viral infections with increased transmission during low temperatures has been well established. The current COVID-19 pandemic makes no exception, and temperature has been suggested to play a role on the viability and transmissibility of SARS-CoV-2. The receptor binding domain (RBD) of the Spike glycoprotein binds to the angiotensin-converting enzyme 2 (ACE2) to initiate viral fusion. Studying the effect of temperature on the receptor-Spike interaction, we observed a significant and stepwise increase in RBD-ACE2 affinity at low temperatures, resulting in slower dissociation kinetics. This translated into enhanced interaction of the full Spike to ACE2 receptor and higher viral attachment at low temperatures. Interestingly, the RBD N501Y mutation, present in emerging variants of concern (VOCs) that are fueling the pandemic worldwide, bypassed this requirement. This data suggests that the acquisition of N501Y reflects an adaptation to warmer climates, a hypothesis that remains to be tested.