Emergence in late 2020 of multiple lineages of SARS-CoV-2 Spike protein variants affecting amino acid position 677

Unveiling Inter- and Intra-Patient Sequence Variability with a Multi-Sample Coronavirus Target Enrichment Approach

Amid the global challenges posed by the COVID-19 pandemic, unraveling the genomic intricacies of SARS-CoV-2 became crucial. This study explores viral evolution using an innovative high-throughput next-generation sequencing (NGS) approach. By taking advantage of nasal swab and mouthwash samples from patients who tested positive for COVID-19 across different geographical regions during sequential infection waves, our study applied a targeted enrichment protocol and pooling strategy to increase detection sensitivity. The approach was extremely efficient, yielding a large number of reads and mutations distributed across 10 distinct viral gene regions. Notably, the genes Envelope, Nucleocapsid, and Open Reading Frame 8 had the highest number of unique mutations per 1000 nucleotides, with both spike and Nucleocapsid genes showing evidence for positive selection. Focusing on the spike protein gene, crucial in virus replication and immunogenicity, our findings show a dynamic SARS-CoV-2 evolution, emphasizing the virus-host interplay. Moreover, the pooling strategy facilitated subtle sequence variability detection. Our findings painted a dynamic portrait of SARS-CoV-2 evolution, emphasizing the intricate interplay between the virus and its host populations and accentuating the importance of continuous genomic surveillance to understand viral dynamics. As SARS-CoV-2 continues to evolve, this approach proves to be a powerful, versatile, fast, and cost-efficient screening tool for unraveling emerging variants, fostering understanding of the virus's genetic landscape.

Frequency of SARS-CoV-2 variants identified by real-time PCR in the AUNA healthcare network, Peru

Introduction

In Peru, on 11 February 2023, the Ministry of Health registered 4 million patients infected with COVID-19 and around 219,260 deaths. In 2020, the SARS-CoV-2 virus was acquiring mutations that impacted the properties of transmissibility, infectivity, and immune evasion, leading to new lineages. In the present study, the frequency of COVID-19 variants was determined during 2021 and 2022 in patients treated in the AUNA healthcare network.

Methods

The methodology used to detect mutations and identify variants was the Allplex™ SARS-CoV-2 Variants Assay I, II, and VII kit RT-PCR. The frequency of variants was presented by epidemiological weeks.

Results

In total, 544 positive samples were evaluated, where the Delta, Omicron, and Gamma variants were identified. The Delta variant was found in 242 (44.5%) patients between epidemiological weeks 39 and 52 in 2021. In the case of Gamma, it was observed in 8 (1.5%) patients at weeks 39, 41, 43, 45, and 46 of 2021. The Omicron variant was the most frequent with 289 (53.1%) patients during weeks 49 to 52 of 2021 and 1 to 22 of 2022. During weeks 1 through 22 of 2022, it was possible to discriminate between BA. 1 (n = 32) and BA.2 (n = 82).

Conclusion

The rapid identification of COVID-19 variants through the RT-PCR methodology contributes to timely epidemiological surveillance, as well as appropriate patient management.

Within-host evolutionary dynamics and tissue compartmentalization during acute SARS-CoV-2 infection

The global evolution of SARS-CoV-2 depends in part upon the evolutionary dynamics within individual hosts with varying immune histories. To characterize the within-host evolution of acute SARS-CoV-2 infection, we sequenced saliva and nasal samples collected daily from vaccinated and unvaccinated individuals early during infection. We show that longitudinal sampling facilitates high-confidence genetic variant detection and reveals evolutionary dynamics missed by less-frequent sampling strategies. Within-host dynamics in both unvaccinated and vaccinated individuals appeared largely stochastic; however, in rare cases, minor genetic variants emerged to frequencies sufficient for forward transmission. Finally, we detected significant genetic compartmentalization of viral variants between saliva and nasal swab sample sites in many individuals. Altogether, these data provide a high-resolution profile of within-host SARS-CoV-2 evolutionary dynamics.IMPORTANCEWe detail the within-host evolutionary dynamics of SARS-CoV-2 during acute infection in 31 individuals using daily longitudinal sampling. We characterized patterns of mutational accumulation for unvaccinated and vaccinated individuals, and observed that temporal variant dynamics in both groups were largely stochastic. Comparison of paired nasal and saliva samples also revealed significant genetic compartmentalization between tissue environments in multiple individuals. Our results demonstrate how selection, genetic drift, and spatial compartmentalization all play important roles in shaping the within-host evolution of SARS-CoV-2 populations during acute infection.

Novel Mutations in the Non-Structure Protein 2 of SARS-CoV-2

Introduction

Mutation in the genome of SARS-CoV-2 may play a role in immune evasion, pathogenicity, and speed of its transmission. Our investigation aimed to evaluate the mutations that exist in the NSP2.

Materials and Method

RNA was extracted from nasopharyngeal swabs from 100 COVID-19 patients. RT-PCR was performed on all samples using NSP2-specific primers. Following gel electrophoresis, the bands were cut, purified, and sequenced using the Sanger method. After sequencing, 90 sequences could be used for further analysis. Bioinformatics analysis was conducted to investigate the effect of mutations on protein structure, stability, prediction of homology models, and phylogeny tree.

Results

The patients' mean age was 51.08. The results revealed that 8 of the 17 NSP2 mutations (R207C, T224I, G262V, T265I, K337D, N348S, G392D, and I431M) were missense. One deletion was also found in NSP2. Among NSP2 missense mutations studied, K337D and G392D increased structural stability while the others decreased it. The homology-designed models demonstrated that the homologies were comparable to the sequences of the Wuhan-HU-1 virus.

Conclusion

Our study suggested that the mutations K337D and G392D modulate the stability of NSP2, and tracking viral evolution should be implemented and vaccine development updated.

[WITHDRAWN] SPLASH: a statistical, reference-free genomic algorithm unifies biological discovery

The authors have withdrawn this manuscript due to a duplicate posting of manuscript number BIORXIV/2022/497555. Therefore, the authors do not wish this work to be cited as reference for the project. If you have any questions, please contact the corresponding author. The correct preprint can be found at doi: https://doi.org/10.1101/2022.06.24.497555.

Cross-Protection Induced by Highly Conserved Human B, CD4+, and CD8+ T Cell Epitopes-Based Coronavirus Vaccine Against Severe Infection, Disease, and Death Caused by Multiple SARS-CoV-2 Variants of Concern

Background

The Coronavirus disease 2019 (COVID-19) pandemic has created one of the largest global health crises in almost a century. Although the current rate of SARS-CoV-2 infections has decreased significantly; the long-term outlook of COVID-19 remains a serious cause of high death worldwide; with the mortality rate still surpassing even the worst mortality rates recorded for the influenza viruses. The continuous emergence of SARS-CoV-2 variants of concern (VOCs), including multiple heavily mutated Omicron sub-variants, have prolonged the COVID-19 pandemic and outlines the urgent need for a next-generation vaccine that will protect from multiple SARS-CoV-2 VOCs.

Methods

In the present study, we designed a multi-epitope-based Coronavirus vaccine that incorporated B, CD4+, and CD8+ T cell epitopes conserved among all known SARS-CoV-2 VOCs and selectively recognized by CD8+ and CD4+ T-cells from asymptomatic COVID-19 patients irrespective of VOC infection. The safety, immunogenicity, and cross-protective immunity of this pan-Coronavirus vaccine were studied against six VOCs using an innovative triple transgenic h-ACE-2-HLA-A2/DR mouse model.

Results

The Pan-Coronavirus vaccine: (i) is safe; (ii) induces high frequencies of lung-resident functional CD8+ and CD4+ TEM and TRM cells; and (iii) provides robust protection against virus replication and COVID-19-related lung pathology and death caused by six SARS-CoV-2 VOCs: Alpha (B.1.1.7), Beta (B.1.351), Gamma or P1 (B.1.1.28.1), Delta (lineage B.1.617.2) and Omicron (B.1.1.529).

Conclusions

A multi-epitope pan-Coronavirus vaccine bearing conserved human B and T cell epitopes from structural and non-structural SARS-CoV-2 antigens induced cross-protective immunity that cleared the virus, and reduced COVID-19-related lung pathology and death caused by multiple SARS-CoV-2 VOCs.

The relevant information about the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using the five-question approach (when, where, what, why, and how) and its impact on the environment

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is regarded as a threat because it spreads quickly across the world without requiring a passport or establishing an identity. This tiny virus has wreaked havoc on people's lives, killed people, and created psychological problems all over the world. The viral spike protein (S) significantly contributes to host cell entry, and mutations associated with it, particularly in the receptor-binding protein (RBD), either facilitate the escape of virus from neutralizing antibodies or enhance its transmission by increasing the affinity for cell entry receptor, angiotensin-converting enzyme 2 (ACE2). The initial variants identified in Brazil, South Africa, and the UK have spread to various countries. On the other hand, new variants are being detected in India and the USA. The viral genome and proteome were applied for molecular detection techniques, and nanotechnology particles and materials were utilized in protection and prevention strategies. Consequently, the SARS-CoV-2 pandemic has resulted in extraordinary scientific community efforts to develop detection methods, diagnosis tools, and effective antiviral drugs and vaccines, where prevailing academic, governmental, and industrial institutions and organizations continue to engage themselves in large-scale screening of existing drugs, both in vitro and in vivo. In addition, COVID-19 pointed on the possible solutions for the environmental pollution globe problem. Therefore, this review aims to address SARS-CoV-2, its transmission, where it can be found, why it is severe in some people, how it can be stopped, its diagnosis and detection techniques, and its relationship with the environment.

Whole Sequencing and Detailed Analysis of SARS-CoV-2 Genomes in Southeast Spain: Identification of Recurrent Mutations in the 20E (EU1) Variant with Some Clinical Implications

During the COVID-19 pandemic caused by SARS-CoV-2, new waves have been associated with new variants and have the potential to escape vaccinations. Therefore, it is useful to conduct retrospective genomic surveillance research. Herein, we present a detailed analysis of 88 SARS-CoV-2 genomes belonging to samples taken from COVID-19 patients from October 2020 to April 2021 at the “Reina Sofía” Hospital (Murcia, Spain) focused to variant appeared later. The results at the mentioned stage show the turning point since the 20E (EU1) variant was still prevalent (71.6%), but Alpha was bursting to 14.8%. Concern mutations have been found in 5 genomes classified as 20E (EU1), which were not characteristic of this still little evolved variant. Most of those mutations are found in the spike protein, namely Δ69–70, E484K, Q675H and P681H. However, a relevant deletion in ORF1a at positions 3675–3677 was also identified. These mutations have been reported in many later SARS-CoV-2 lineages, including Omicron. Taken together, our data suggest that preferential emergence mutations could already be present in the early converging evolution. Aside from this, the molecular information has been contrasted with clinical data. Statistical analyses suggest that the correlation between age and severity criteria is significantly higher in the viral samples with more accumulated changes.

SARS-CoV-2 S Mutations: A Lesson from the Viral World to Understand How Human Furin Works

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is the etiological agent responsible for the worldwide pandemic and has now claimed millions of lives. The virus combines several unusual characteristics and an extraordinary ability to spread among humans. In particular, the dependence of the maturation of the envelope glycoprotein S from Furin enables the invasion and replication of the virus virtually within the entire body, since this cellular protease is ubiquitously expressed. Here, we analyzed the naturally occurring variation of the amino acids sequence around the cleavage site of S. We found that the virus grossly mutates preferentially at P positions, resulting in single residue replacements that associate with gain-of-function phenotypes in specific conditions. Interestingly, some combinations of amino acids are absent, despite the evidence supporting some cleavability of the respective synthetic surrogates. In any case, the polybasic signature is maintained and, as a consequence, Furin dependence is preserved. Thus, no escape variants to Furin are observed in the population. Overall, the SARS-CoV-2 system per se represents an outstanding example of the evolution of substrate-enzyme interaction, demonstrating a fast-tracked optimization of a protein stretch towards the Furin catalytic pocket. Ultimately, these data disclose important information for the development of drugs targeting Furin and Furin-dependent pathogens.

Isolation and characterization of a SARS-CoV-2 variant with a Q677H mutation in the spike protein

We isolated 20 SARS-CoV-2 strains from positive clinical samples collected in Columbus, Ohio, and investigated the replication of one pair of isolates: a clade 20G strain and a variant of this strain carrying a Q677H mutation in the spike protein and six other amino acid mutations. The OSU.20G variant replicated to a higher peak infectious titer than the 20G base strain in Vero-E6 cells, but the titers were similar when both strains were grown in Calu-3 cells. These results suggest that the OSU.20G variant has increased replication fitness compared to the 20G base strain. This may have contributed to its emergence in December 2020-January 2021.

Multiple Mutations Associated with Emergent Variants Can Be Detected as Low-Frequency Mutations in Early SARS-CoV-2 Pandemic Clinical Samples

Genetic analysis of intra-host viral populations provides unique insight into pre-emergent mutations that may contribute to the genotype of future variants. Clinical samples positive for SARS-CoV-2 collected in California during the first months of the pandemic were sequenced to define the dynamics of mutation emergence as the virus became established in the state. Deep sequencing of 90 nasopharyngeal samples showed that many mutations associated with the establishment of SARS-CoV-2 globally were present at varying frequencies in a majority of the samples, even those collected as the virus was first detected in the US. A subset of mutations that emerged months later in consensus sequences were detected as subconsensus members of intra-host populations. Spike mutations P681H, H655Y, and V1104L were detected prior to emergence in variant genotypes, mutations were detected at multiple positions within the furin cleavage site, and pre-emergent mutations were identified in the nucleocapsid and the envelope genes. Because many of the samples had a very high depth of coverage, a bioinformatics pipeline, "Mappgene", was established that uses both iVar and LoFreq variant calling to enable identification of very low-frequency variants. This enabled detection of a spike protein deletion present in many samples at low frequency and associated with a variant of concern.

Multimodal surveillance of SARS-CoV-2 at a university enables development of a robust outbreak response framework

BACKGROUND

Universities are vulnerable to infectious disease outbreaks, making them ideal environments to study transmission dynamics and evaluate mitigation and surveillance measures. Here, we analyze multimodal COVID-19-associated data collected during the 2020-2021 academic year at Colorado Mesa University and introduce a SARS-CoV-2 surveillance and response framework.

METHODS

We analyzed epidemiological and sociobehavioral data (demographics, contact tracing, and WiFi-based co-location data) alongside pathogen surveillance data (wastewater and diagnostic testing, and viral genomic sequencing of wastewater and clinical specimens) to characterize outbreak dynamics and inform policy. We applied relative risk, multiple linear regression, and social network assortativity to identify attributes or behaviors associated with contracting SARS-CoV-2. To characterize SARS-CoV-2 transmission, we used viral sequencing, phylogenomic tools, and functional assays.

FINDINGS

Athletes, particularly those on high-contact teams, had the highest risk of testing positive. On average, individuals who tested positive had more contacts and longer interaction durations than individuals who never tested positive. The distribution of contacts per individual was overdispersed, although not as overdispersed as the distribution of phylogenomic descendants. Corroboration via technical replicates was essential for identification of wastewater mutations.

CONCLUSIONS

Based on our findings, we formulate a framework that combines tools into an integrated disease surveillance program that can be implemented in other congregate settings with limited resources.

FUNDING

This work was supported by the National Science Foundation, the Hertz Foundation, the National Institutes of Health, the Centers for Disease Control and Prevention, the Massachusetts Consortium on Pathogen Readiness, the Howard Hughes Medical Institute, the Flu Lab, and the Audacious Project.

Early SARS-CoV-2 dynamics and immune responses in unvaccinated participants of an intensely sampled longitudinal surveillance study

Background

A comprehensive understanding of the SARS-CoV-2 infection dynamics and the ensuing host immune responses is needed to explain the pathogenesis as it relates to viral transmission. Knowledge gaps exist surrounding SARS-CoV-2 in vivo kinetics, particularly in the earliest stages after exposure.

Methods

An ongoing, workplace clinical surveillance study was used to intensely sample a small cohort longitudinally. Nine study participants who developed COVID-19 between November, 2020 and March, 2021 were monitored at high temporal resolution for three months in terms of viral loads as well as associated inflammatory biomarker and antibody responses. CD8 + T cells targeting SARS-CoV-2 in blood samples from study participants were evaluated.

Results

Here we show that the resulting datasets, supported by Bayesian modeling, allowed the underlying kinetic processes to be described, yielding a number of unexpected findings. Early viral replication is rapid (median doubling time, 3.1 h), providing a narrow window between exposure and viral shedding, while the clearance phase is slow and heterogeneous. Host immune responses different widely across participants.

Conclusions

Results from our small study give a rare insight into the life-cycle of COVID-19 infection and hold a number of important biological, clinical, and public health implications.

SARS-CoV-2 Monitoring in Wastewater Reveals Novel Variants and Biomarkers of Infection

Wastewater-based epidemiology (WBE) is a popular tool for the early indication of community spread of infectious diseases. WBE emerged as an effective tool during the COVID-19 pandemic and has provided meaningful information to minimize the spread of infection. Here, we present a combination of analyses using the correlation of viral gene copies with clinical cases, sequencing of wastewater-derived RNA for the viral mutants, and correlative analyses of the viral gene copies with the bacterial biomarkers. Our study provides a unique platform for potentially using the WBE-derived results to predict the spread of COVID-19 and the emergence of new variants of concern. Further, we observed a strong correlation between the presence of SARS-CoV-2 and changes in the microbial community of wastewater, particularly the significant changes in bacterial genera belonging to the families of Lachnospiraceae and Actinomycetaceae. Our study shows that microbial biomarkers could be utilized as prediction tools for future infectious disease surveillance and outbreak responses. Overall, our comprehensive analyses of viral spread, variants, and novel bacterial biomarkers will add significantly to the growing body of literature on WBE and COVID-19.

SARS-CoV-2 Genetic Diversity and Lineage Dynamics in Egypt during the First 18 Months of the Pandemic

COVID-19 was first diagnosed in Egypt on 14 February 2020. By the end of November 2021, over 333,840 cases and 18,832 deaths had been reported. As part of the national genomic surveillance, 1027 SARS-CoV-2 near whole-genomes were generated and published by the end of July 2021. Here we describe the genomic epidemiology of SARS-CoV-2 in Egypt over this period using a subset of 976 high-quality Egyptian genomes analyzed together with a representative set of global sequences within a phylogenetic framework. A single lineage, C.36, introduced early in the pandemic was responsible for most of the cases in Egypt. Furthermore, to remain dominant in the face of mounting immunity from previous infections and vaccinations, this lineage acquired several mutations known to confer an adaptive advantage. These results highlight the value of continuous genomic surveillance in regions where VOCs are not predominant and the need for enforcement of public health measures to prevent expansion of the existing lineages.

A Method for Variant Agnostic Detection of SARS-CoV-2, Rapid Monitoring of Circulating Variants, and Early Detection of Emergent Variants Such as Omicron

The rapid emergence of SARS-CoV-2 variants raised public health questions concerning the capability of diagnostic tests to detect new strains, the efficacy of vaccines, and how to map the geographical distribution of variants to understand transmission patterns and loads on healthcare resources. Next-generation sequencing (NGS) is the primary method for detecting and tracing new variants, but it is expensive, and it can take weeks before sequence data are available in public repositories. This article describes a customizable reverse transcription PCR (RT-PCR)-based genotyping approach which is significantly less expensive, accelerates reporting, and can be implemented in any lab that performs RT-PCR. Specific single-nucleotide polymorphisms (SNPs) and indels were identified which had high positive-percent agreement (PPA) and negative-percent agreement (NPA) compared to NGS for the major genotypes that circulated through September 11, 2021. Using a 48-marker panel, testing on 1,031 retrospective SARS-CoV-2 positive samples yielded a PPA and NPA ranging from 96.3 to 100% and 99.2 to 100%, respectively, for the top 10 most prevalent World Health Organization (WHO) lineages during that time. The effect of reducing the quantity of panel markers was explored, and a 16-marker panel was determined to be nearly as effective as the 48-marker panel at lineage assignment. Responding to the emergence of Omicron, a genotyping panel was developed which distinguishes Delta and Omicron using four highly specific SNPs. The results demonstrate the utility of the condensed panel to rapidly track the growing prevalence of Omicron across the US in December 2021 and January 2022.

The First Geographic Identification by Country of Sustainable Mutations of SARS-COV2 Sequence Samples: Worldwide Natural Selection Trends

The high mutation rates of RNA viruses, coupled with short generation times and large population sizes, allow viruses to evolve rapidly and adapt to the host environment. The rapidity of viral mutation also causes problems in developing successful vaccines and antiviral drugs. With the spread of SARS-CoV-2 worldwide, thousands of mutations have been identified, some of which have relatively high incidences, but their potential impacts on virus characteristics remain unknown. The present study analyzed mutation patterns, SARS-CoV-2 AASs retrieved from the GISAID database containing 10,500,000 samples. Python 3.8.0 programming language was utilized to pre-process FASTA data, align to the reference sequence, and analyze the sequences. Upon completion, all mutations discovered were categorized based on geographical regions and dates. The most stable mutations were found in nsp1(8% S135R), nsp12(99.3% P323L), nsp16 (1.2% R216C), envelope (30.6% T9I), spike (97.6% D614G), and Orf8 (3.5% S24L), and were identified in the United States on April 3, 2020, and England, Gibraltar, and, New Zealand, on January 1, 2020, respectively. The study of mutations is the key to improving understanding of the function of the SARS-CoV-2, and recent information on mutations helps provide strategic planning for the prevention and treatment of this disease. Viral mutation studies could improve the development of vaccines, antiviral drugs, and diagnostic assays designed with high accuracy, specifically useful during pandemics. This knowledge helps to be one step ahead of new emergence variants.

SARS-COV-2 Notable Mutations and Variants: A Review Article

SARS-COV-2 (COVID-19) the virus that caused an epidemic of sever acute respiratory syndrome is what the world has been dealing with since Dec 2019. As the pandemic continues different variants that emerge during mutations have become the latest concern, with notable examples detected in South Africa, Brazil, and UK. Variants are complicated and each one is a collection of several mutations, all of which have the potential to change the virus in unexpected ways. Studying variants is imperative as they can lead the epidemic to the increase of population immunity. In the present study, we reviewed key mutations and concerning variants according to the WHO tracking Sars-Cov-2 program. Databases were searched through Feb to Mar 2022. Overall, 477 studies were extracted from databases, among them 165 studies included mutations, 239 included COVID-19 variants and 43 included both mutations and variants. At the final step of data screening 24 studies associated to mutations, 31 studies with the highlighted information on COVID-19 variants and 31 studies related to both mutations and variants were extracted for this review article. In conclusion, analyses of the genomic sequence of SARS-CoV-2 indicate that structural proteins are key molecules in the assembly of virus while NSPs can have different biochemical properties and possibly cellular functions.

Increased Abundance of Achromobacter xylosoxidans and Bacillus cereus in Upper Airway Transcriptionally Active Microbiome of COVID-19 Mortality Patients Indicates Role of Co-Infections in Disease Severity and Outcome

The modulators of severe COVID-19 have emerged as the most intriguing features of SARS-CoV-2 pathogenesis. This is especially true as we are encountering variants of concern (VOC) with increased transmissibility and vaccination breakthroughs. Microbial co-infections are being investigated as one of the crucial factors for exacerbation of disease severity and complications of COVID-19. A key question remains whether early transcriptionally active microbial signature/s in COVID-19 patients can provide a window for future disease severity susceptibility and outcome? Using complementary metagenomics sequencing approaches, respiratory virus oligo panel (RVOP) and Holo-seq, our study highlights the possible functional role of nasopharyngeal early resident transcriptionally active microbes in modulating disease severity, within recovered patients with sub-phenotypes (mild, moderate, severe) and mortality. The integrative analysis combines patients' clinical parameters, SARS-CoV-2 phylogenetic analysis, microbial differential composition, and their functional role. The clinical sub-phenotypes analysis led to the identification of transcriptionally active bacterial species associated with disease severity. We found significant transcript abundance of Achromobacter xylosoxidans and Bacillus cereus in the mortality, Leptotrichia buccalis in the severe, Veillonella parvula in the moderate, and Actinomyces meyeri and Halomonas sp. in the mild COVID-19 patients. Additionally, the metabolic pathways, distinguishing the microbial functional signatures between the clinical sub-phenotypes, were also identified. We report a plausible mechanism wherein the increased transcriptionally active bacterial isolates might contribute to enhanced inflammatory response and co-infections that could modulate the disease severity in these groups. Current study provides an opportunity for potentially using these bacterial species for screening and identifying COVID-19 patient sub-groups with severe disease outcome and priority medical care. IMPORTANCE COVID-19 is invariably a disease of diverse clinical manifestation, with multiple facets involved in modulating the progression and outcome. In this regard, we investigated the role of transcriptionally active microbial co-infections as possible modulators of disease pathology in hospital admitted SARS-CoV-2 infected patients. Specifically, can there be early nasopharyngeal microbial signatures indicative of prospective disease severity? Based on disease severity symptoms, the patients were segregated into clinical sub-phenotypes: mild, moderate, severe (recovered), and mortality. We identified significant presence of transcriptionally active isolates, Achromobacter xylosoxidans and Bacillus cereus in the mortality patients. Importantly, the bacterial species might contribute toward enhancing the inflammatory responses as well as reported to be resistant to common antibiotic therapy, which together hold potential to alter the disease severity and outcome.

Perspectives: SARS-CoV-2 Spike Convergent Evolution as a Guide to Explore Adaptive Advantage

Viruses rapidly co-evolve with their hosts. The 9 million sequenced SARS-CoV-2 genomes by March 2022 provide a detailed account of viral evolution, showing that all amino acids have been mutated many times. However, only a few became prominent in the viral population. Here, we investigated the emergence of the same mutations in unrelated parallel lineages and the extent of such convergent evolution on the molecular level in the spike (S) protein. We found that during the first phase of the pandemic (until mid 2021, before mass vaccination) 31 mutations evolved independently ≥3-times within separated lineages. These included all the key mutations in SARS-CoV-2 variants of concern (VOC) at that time, indicating their fundamental adaptive advantage. The omicron added many more mutations not frequently seen before, which can be attributed to the synergistic nature of these mutations, which is more difficult to evolve. The great majority (24/31) of S-protein mutations under convergent evolution tightly cluster in three functional domains; N-terminal domain, receptor-binding domain, and Furin cleavage site. Furthermore, among the S-protein receptor-binding motif mutations, ACE2 affinity-improving substitutions are favoured. Next, we determined the mutation space in the S protein that has been covered by SARS-CoV-2. We found that all amino acids that are reachable by single nucleotide changes have been probed multiple times in early 2021. The substitutions requiring two nucleotide changes have recently (late 2021) gained momentum and their numbers are increasing rapidly. These provide a large mutation landscape for SARS-CoV-2 future evolution, on which research should focus now.

Mutations of the SARS-CoV-2 Spike Glycoprotein Detected in Cats and Their Effect on Its Structure and Function

The high frequency of Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) mutations and homology of the Angiotensin-Converting Enzyme-2 (ACE2) cell receptors in various hosts help the virus transcend species barriers. In this study, we investigated the mutations of the SARS-CoV-2 spike glycoprotein detected in cats and their effect on its structure and function. Interestingly, some of these mutations are reported here in cats for the first time. Structural analysis showed seven residue substitutions in the spike glycoprotein. Four of the detected mutations are located on the spike surface, which are critical interaction points for neutralizing antibodies. Furthermore, three of the reported mutations could facilitate viral binding to the ACE2 host receptor, influence S1/S2 cleavage, destabilize the β-hairpin structure of the S2 and enhance viral infectivity. Structural modeling and phylogenic analysis of the ACE2 receptor provided an indication of the binding capacity of the virus to the specific cell receptors of different species and hosts. The presented work highlights the effects of the residue substitutions on viral evasion, infectivity and possibility of SARS-CoV-2 spillover between humans and cats. In addition, the work paves the way for in-depth molecular investigation into the relationship between SARS-CoV-2 receptor binding and host susceptibility.

The Biological Functions and Clinical Significance of SARS-CoV-2 Variants of Corcern

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is continuing to evolve, emerging novel variants with spike protein mutations. Although most mutations emerged in the SARS-CoV-2 genome are neutral or mildly deleterious, a small number of mutations can affect virus phenotype that confers the virus a fitness advantage. These mutations can enhance viral replication, raise the risk of reinfection and blunt the potency of neutralizing antibodies triggered by previous infection and vaccination. Since December 2020, the SARS-CoV-2 has emerged five quickly spreading strains, designated variants of concern (VOCs), including the Alpha (B.1.1.7) variant, the Beta (B.1.351) variant, the Gamma (P.1) variant, the Delta (B.1.617.2) variant and the Omicron (B.1.1.529) variant. These variants have a high number of the mutations in the spike protein that promotes viral cell entry through the angiotensin-converting enzyme -2 (ACE2). Mutations that have arisen in the receptor binding domain (RBD) of the spike protein are of great concern due to their potential to evade neutralizing antibodies triggered by previous infection and vaccines. The Alpha variant emerged in the United Kingdom in the second half of 2020 that has spread quickly globally and acquired the E484K mutation in the United Kingdom and the United States. The Beta and Gamma variants emerged in South Africa and Brazil, respectively, that have additional mutations at positions E484 and K417 in the RBD. SARS-CoV-2 variants containing the combination of N501Y, E484K, and K417N/T mutations exhibit remarkably decreased sensitivity to neutralizing antibodies mediated by vaccination or previous infection. The Gamma variant may result in more severe disease than other variants do even in convalescent individuals. The Delta variant emerged in India in December 2020 and has spread to many countries including the United States and the United Kingdom. The Delta variant has 8 mutations in the spike protein, some of which can influence immune responses to the key antigenic regions of RBD. In early November 2021, the Omicron (B.1.1.529) variant was first detected in Botswana and South Africa. The Omicron variant harbors more than 30 mutations in the spike protein, many of which are located within the RBD, which have been associated with increased transmissibility and immune evasion after previous infection and vaccination. Additionally, the Omicron variant contains 3 deletions and one insertion in the spike protein. Recently, the Omicron variant has been classified into three sublineages, including BA.1, BA.2, and BA.3, with strikingly different genetic characteristics. The Omicron BA.2 sublineage has different virological landscapes, such as transmissibility, pathogenicity and resistance to the vaccine-induced immunity compared to BA.1 and BA.3 sublineages. Mutations emerged in the RBD of the spike protein of VOCs increase viral replication, making the virus more infectious and more transmissible and enable the virus to evade vaccine-elicited neutralizing antibodies. Unfortunately, the emergence of novel SARS-CoV-2 VOCs has tempered early optimism regarding the efficacy of COVID-19 vaccines. This review addresses the biological and clinical significance of SARS-CoV-2 VOCs and their impact on neutralizing antibodies mediated by existing COVID-19 vaccines.

nSARS-CoV-2 and COVID-19 Pandemic: From Emergence to Vaccination

Since its first emergence in Wuhan, China, the novel severe acute respiratory syndrome coronavirus-2 (nSARS-CoV-2)-associated coronavirus disease 2019 (COVID-19) has alarmingly disrupted the world’s healthcare systems and evolved as a major public health threat around the globe. Despite the advent and emergency use listing (EUL) of mRNA- and adenovirus-based vaccines to prevent the further transmission of SARS-CoV-2 infection, the pandemic burden is still significant worldwide as new cases are being reported daily. It is the first time in vaccine history that vaccines against SARS-CoV-2 have been rapidly designed, developed, and clinically evaluated and surprisingly, they have worked better than clinical trial data predicted. However, this EUL of vaccines prior to full approvals stems from the perception of inadequate testing and experience with benefit–risk balance. Similarly, the emergence of superspreader SARS-CoV-2 mutant virus strains at the end of 2020 has also raised concerns about the efficacies of approved vaccines in real-world clinical scenarios. The inconclusive, murky, and anecdotal reports about vaccine hesitancy, antibody-dependent enhancement of disease risk in vaccine injectors, and certain severe adverse events have also frightened a large segment of the world’s population, preventing them from receiving the vaccine. This review presents an overview of the remarkable efforts rendered by different vaccine producers to combat the pandemic, explains the challenges of vaccine safety and efficacies against SARS-CoV-2 variants of concern, and explores their potential roles in eradicating the COVID-19 pandemic.

SARS-CoV-2 Lineage A.27: New Data from African Countries and Dynamics in the Context of the COVID-19 Pandemic

SARS-CoV-2 is constantly evolving with lineages emerging and others eclipsing. Some lineages have an important epidemiological impact and are known as variants of interest (VOIs), variants under monitoring (VUMs) or variants of concern (VOCs). Lineage A.27 was first defined as a VUM since it holds mutations of concern. Here, we report additional lineage A.27 data and sequences from five African countries and describe the molecular characteristics, and the genetic history of this lineage worldwide. Based on the new sequences investigated, the most recent ancestor (tMRCA) of lineage A.27 was estimated to be from April 2020 from Niger. It then spread to Europe and other parts of the world with a peak observed between February and April 2021. The detection rate of A.27 then decreased with only a few cases reported during summer 2021. The phylogenetic analysis revealed many sub-lineages. Among them, one was defined by the substitution Q677H in the spike (S) gene, one was defined by the substitution D358N in the nucleoprotein (N) gene and one was defined by the substitution A2143V in the ORF1b gene. This work highlights the importance of molecular characterization and the timely submission of sequences to correctly describe the circulation of particular strains in order to be proactive in monitoring the pandemic.

Structural Dynamics and Molecular Evolution of the SARS-CoV-2 Spike Protein

The ongoing coronavirus disease 2019 (COVID-19) pandemic demonstrates the threat posed by novel coronaviruses to human health. Coronaviruses share a highly conserved cell entry mechanism mediated by the spike protein, the sole product of the S gene. The structural dynamics by which the spike protein orchestrates infection illuminate how antibodies neutralize virions and how S mutations contribute to viral fitness. Here, we review the process by which spike engages its proteinaceous receptor, angiotensin converting enzyme 2 (ACE2), and how host proteases prime and subsequently enable efficient membrane fusion between virions and target cells. We highlight mutations common among severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern and discuss implications for cell entry. Ultimately, we provide a model by which sarbecoviruses are activated for fusion competency and offer a framework for understanding the interplay between humoral immunity and the molecular evolution of the SARS-CoV-2 Spike. In particular, we emphasize the relevance of the Canyon Hypothesis (M. G. Rossmann, J Biol Chem 264:14587-14590, 1989) for understanding evolutionary trajectories of viral entry proteins during sustained intraspecies transmission of a novel viral pathogen.

Molecular variants of SARS-CoV-2: antigenic properties and current vaccine efficacy

An ongoing pandemic of newly emerged SARS-CoV-2 has puzzled many scientists and health care policymakers around the globe. The appearance of the virus was accompanied by several distinct antigenic changes, specifically spike protein which is a key element for host cell entry of virus and major target of currently developing vaccines. Some of these mutations enable the virus to attach to receptors more firmly and easily. Moreover, a growing number of trials are demonstrating higher transmissibility and, in some of them, potentially more serious forms of illness related to novel variants. Some of these lineages, especially the Beta variant of concern, were reported to diminish the neutralizing activity of monoclonal and polyclonal antibodies present in both convalescent and vaccine sera. This could imply that these independently emerged variants could make antiviral strategies prone to serious threats. The rapid changes in the mutational profile of new clades, especially escape mutations, suggest the convergent evolution of the virus due to immune pressure. Nevertheless, great international efforts have been dedicated to producing efficacious vaccines with cutting-edge technologies. Despite the partial decrease in vaccines efficacy against worrisome clades, most current vaccines are still effective at preventing mild to severe forms of disease and hospital admission or death due to coronavirus disease 2019 (COVID-19). Here, we summarize existing evidence about newly emerged variants of SARS-CoV-2 and, notably, how well vaccines work against targeting new variants and modifications of highly flexible mRNA vaccines that might be required in the future.

Importation, circulation, and emergence of variants of SARS-CoV-2 in the South Indian state of Karnataka

Background: As the coronavirus disease 2019 (COVID-19) pandemic continues, the selection of genomic variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) associated with higher transmission, more severe disease, re-infection, and immune escape are a cause for concern. Such variants have been reported from the UK (B.1.1.7), South Africa (B.1.351) and, Brazil (P.1/B.1.1.28). We performed this study to track the importation, spread, and emergence of variants locally. Methods: We sequenced whole genomes of SARS-CoV-2 from international travellers (n=75) entering Karnataka, South India, between Dec 22, 2020 and Jan 31, 2021, and from positive cases in the city of Bengaluru (n=108), between Nov 22, 2020- Jan 22, 2021, as well as a local outbreak. We present the lineage distribution and analysis of these sequences. Results: Genomes from the study group into 34 lineages. Variant B.1.1.7 was introduced by international travel (24/73, 32.9%). Lineage B.1.36 and B.1 formed a major fraction of both imported (B.1.36: 20/73, 27.4%; B.1: 14/73, 19.2%), and circulating viruses (B.1.36: 45/103; 43.7%,. B.1: 26/103; 25.2%). The lineage B.1.36 was also associated with a local outbreak. We detected nine amino acid changes, previously associated with immune escape, spread across multiple lineages. The N440K change was detected in 45/162 (27.7%) of the sequences, 37 of these were in the B.1.36 lineage (37/65, 56.92%) Conclusions: Our data support the idea that variants of concern spread by travel. Viruses with amino acid replacements associated with immune escape are already circulating. It is critical to check transmission and monitor changes in SARS-CoV-2 locally.

Limited spread of a rare spike E484K-harboring SARS-CoV-2 in Marseille, France

We detected SARS-CoV-2 of PANGO lineage R.1 with the spike substitution E484K in three patients. Eleven other sequences in France and 8,831 worldwide were available from GISAID, 92% originating from Japan. The three genome sequences from our institute were phylogenetically closest to another from Guinea-Conakry, where one of the patients had travelled. These viruses did not exhibit any unusual features in cell culture. Spike structural predictions indicated a 1.3-time higher transmissibility index than for the globally spread B.1.1.7 variant but also an affinity loss for gangliosides that might have slowed dissemination. The spread of new SARS-CoV-2 mutants/variants is still not well understood and therefore difficult to predict, and this hinders implementation of effective preventive measures, including adapted vaccines.

Occurrence of a substitution or deletion of SARS-CoV-2 spike amino acid 677 in various lineages in Marseille, France

Great concerns have been raised about SARS-CoV-2 variants over the past six months. At the end of 2020, an increasing incidence of spike substitutions Q677H/P was described in the USA, which involved six independent lineages. We searched for changes to this amino acid in the sequence database of SARS-CoV-2 genomes obtained at the IHU Méditerranée Infection (Marseille, France) from 3634 patients sampled between February 2020 and April 2021. In seven genomes (0.2%), we found a deletion of five amino acids at spike positions 675-679 (QTQTN) including Q677, and in 76 genomes (2.3%) we found a Q677H substitution. The 83 genomes were classified in ten different Pangolin lineages. Genomes with a spike Q677 deletion were obtained from respiratory samples collected in six cases between 28 March 2020 and 12 October 2020 and in one case on 1 February 2021. The Q677H substitution was found in genomes all obtained from respiratory samples collected from 19 January 2021 and were classified in seven different lineages. Most of these genomes (41 cases) were of UK variant. Two others were classified in the B.1.160 Pangolin lineage (Marseille-4 variant) which was first detected in July 2020 in our institute but was devoid of this substitution until 19 January 2021. Also, eight genomes were classified in the A.27/Marseille-501 lineage which was first detected in our institute in January 2021 and which either harboured or did not harbour the Q677H substitution. Thus, the spike Q677H substitution should be considered as another example of convergent evolution, as it is the case of spike substitutions L18F, E484K, L452R, and N501Y which also independently appeared in various lineages.

Estimation of Secondary Household Attack Rates for Emergent Spike L452R Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants Detected by Genomic Surveillance at a Community-Based Testing Site in San Francisco

BACKGROUND

Sequencing of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral genome from patient samples is an important epidemiological tool for monitoring and responding to the pandemic, including the emergence of new mutations in specific communities.

METHODS

SARS-CoV-2 genomic sequences were generated from positive samples collected, along with epidemiological metadata, at a walk-up, rapid testing site in the Mission District of San Francisco, California during 22 November to 1 December, 2020, and 10-29 January 2021. Secondary household attack rates and mean sample viral load were estimated and compared across observed variants.

RESULTS

A total of 12 124 tests were performed yielding 1099 positives. From these, 928 high-quality genomes were generated. Certain viral lineages bearing spike mutations, defined in part by L452R, S13I, and W152C, comprised 54.4% of the total sequences from January, compared to 15.7% in November. Household contacts exposed to the "California" or "West Coast" variants (B.1.427 and B.1.429) were at higher risk of infection compared to household contacts exposed to lineages lacking these variants (0.36 vs 0.29, risk ratio [RR] = 1.28; 95% confidence interval [CI]: 1.00-1.64). The reproductive number was estimated to be modestly higher than other lineages spreading in California during the second half of 2020. Viral loads were similar among persons infected with West Coast versus non-West Coast strains, as was the proportion of individuals with symptoms (60.9% vs 64.3%).

CONCLUSIONS

The increase in prevalence, relative household attack rates, and reproductive number are consistent with a modest transmissibility increase of the West Coast variants. Summary: We observed a growing prevalence and modestly elevated attack rate for "West Coast" severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants in a community testing setting in San Francisco during January 2021, suggesting its modestly higher transmissibility.

Emerging SARS-CoV-2 Genotypes Show Different Replication Patterns in Human Pulmonary and Intestinal Epithelial Cells

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) quickly spread worldwide following its emergence in Wuhan, China, and hit pandemic levels. Its tremendous incidence favoured the emergence of viral variants. The current genome diversity of SARS-CoV-2 has a clear impact on epidemiology and clinical practice, especially regarding transmission rates and the effectiveness of vaccines. In this study, we evaluated the replication of different SARS-CoV-2 isolates representing different virus genotypes which have been isolated throughout the pandemic. We used three distinct cell lines, including Vero E6 cells originating from monkeys; Caco-2 cells, an intestinal epithelium cell line originating from humans; and Calu-3 cells, a pulmonary epithelium cell line also originating from humans. We used RT-qPCR to replicate different SARS-CoV-2 genotypes by quantifying the virus released in the culture supernatant of infected cells. We found that the different viral isolates replicate similarly in Caco-2 cells, but show very different replicative capacities in Calu-3 cells. This was especially highlighted for the lineages B.1.1.7, B.1.351 and P.1, which are considered to be variants of concern. These results underscore the importance of the evaluation and characterisation of each SARS-CoV-2 isolate in order to establish the replication patterns before performing tests, and of the consideration of the ideal SARS-CoV-2 genotype-cell type pair for each assay.

SARS-CoV-2 Variants and Their Relevant Mutational Profiles: Update Summer 2021

Since the beginning of the coronavirus disease 2019 (COVID-19) pandemic caused by it, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been undergoing a genetic diversification leading to the emergence of new variants. Nevertheless, a clear definition of the genetic signatures underlying the circulating variants is still missing. Here, we provide a comprehensive insight into mutational profiles characterizing each SARS-CoV-2 variant, focusing on spike mutations known to modulate viral infectivity and/or antigenicity. We focused on variants and on specific relevant mutations reported by GISAID, Nextstrain, Outbreak.info, Pango, and Stanford database websites that were associated with any clinical/diagnostic impact, according to published manuscripts. Furthermore, 1,223,338 full-length high-quality SARS-CoV-2 genome sequences were retrieved from GISAID and used to accurately define the specific mutational patterns in each variant. Finally, mutations were mapped on the three-dimensional structure of the SARS-CoV-2 spike protein to assess their localization in the different spike domains. Overall, this review sheds light and assists in defining the genetic signatures characterizing the currently circulating variants and their clinical relevance. IMPORTANCE Since the emergence of SARS-CoV-2, several recurrent mutations, particularly in the spike protein, arose during human-to-human transmission or spillover events between humans and animals, generating distinct worrisome variants of concern (VOCs) or of interest (VOIs), designated as such due to their clinical and diagnostic impacts. Characterizing these variants and their related mutations is important in tracking SAR-CoV-2 evolution and understanding the efficacy of vaccines and therapeutics based on monoclonal antibodies, convalescent-phase sera, and direct antivirals. Our study provides a comprehensive survey of the mutational profiles characterizing the important SARS-CoV-2 variants, focusing on spike mutations and highlighting other protein mutations.

Role of Q675H Mutation in Improving SARS-CoV-2 Spike Interaction with the Furin Binding Pocket

Genotype screening was implemented in Italy and showed a significant prevalence of new SARS-CoV-2 mutants carrying Q675H mutation, near the furin cleavage site of spike protein. Currently, this mutation, which is expressed on different SARS-CoV-2 lineages circulating worldwide, has not been thoughtfully investigated. Therefore, we performed phylogenetic and biocomputational analysis to better understand SARS-CoV-2 Q675H mutants’ evolutionary relationships with other circulating lineages and Q675H function in its molecular context. Our studies reveal that Q675H spike mutation is the result of parallel evolution because it arose independently in separate evolutionary clades. In silico data show that the Q675H mutation gives rise to a hydrogen-bonds network in the spike polar region. This results in an optimized directionality of arginine residues involved in interaction of spike with the furin binding pocket, thus improving proteolytic exposure of the viral protein. Furin was predicted to have a greater affinity for Q675H than Q675 substrate conformations. As a consequence, Q675H mutation could confer a fitness advantage to SARS-CoV-2 by promoting a more efficient viral entry. Interestingly, here we have shown that Q675H spike mutation is documented in all the VOCs. This finding highlights that VOCs are still evolving to enhance viral fitness and to adapt to the human host. At the same time, it may suggest Q675H spike mutation involvement in SARS-CoV-2 evolution.

The biological and clinical significance of emerging SARS-CoV-2 variants

The past several months have witnessed the emergence of SARS-CoV-2 variants with novel spike protein mutations that are influencing the epidemiological and clinical aspects of the COVID-19 pandemic. These variants can increase rates of virus transmission and/or increase the risk of reinfection and reduce the protection afforded by neutralizing monoclonal antibodies and vaccination. These variants can therefore enable SARS-CoV-2 to continue its spread in the face of rising population immunity while maintaining or increasing its replication fitness. The identification of four rapidly expanding virus lineages since December 2020, designated variants of concern, has ushered in a new stage of the pandemic. The four variants of concern, the Alpha variant (originally identified in the UK), the Beta variant (originally identified in South Africa), the Gamma variant (originally identified in Brazil) and the Delta variant (originally identified in India), share several mutations with one another as well as with an increasing number of other recently identified SARS-CoV-2 variants. Collectively, these SARS-CoV-2 variants complicate the COVID-19 research agenda and necessitate additional avenues of laboratory, epidemiological and clinical research.

SNP and Phylogenetic Characterization of Low Viral Load SARS-CoV-2 Specimens by Target Enrichment

Background: Surveillance of SARS-CoV-2 across the globe has enabled detection of new variants and informed the public health response. With highly sensitive methods like qPCR widely adopted for diagnosis, the ability to sequence and characterize specimens with low titers needs to keep pace.

Methods: Nucleic acids extracted from nasopharyngeal swabs collected from four sites in the United States in early 2020 were converted to NGS libraries to sequence SARS-CoV-2 genomes using metagenomic and xGen target enrichment approaches. Single nucleotide polymorphism (SNP) analysis and phylogeny were used to determine clade assignments and geographic origins of strains.

Results: SARS-CoV-2-specific xGen enrichment enabled full genome coverage for 87 specimens with Ct values <29, corresponding to viral loads of >10,000 cp/ml. For samples with viral loads between 103 and 106 cp/ml, the median genome coverage for xGen was 99.1%, sequence depth was 605X, and the “on-target” rate was 57 ± 21%, compared to 13%, 2X and 0.001 ± 0.016%, respectively, for metagenomic sequencing alone. Phylogenetic analysis revealed the presence of most clades that existed at the time of the study, though clade GH dominated in the Midwest.

Conclusions: Even as vaccines are being widely distributed, a high case load of SARS-CoV-2 infection persists around the world. Viral genetic surveillance has succeeded in warning the public of new variants in circulation and ensured that diagnostic tools remain resilient to a steadily increasing number of mutations. Target capture offers a means of characterizing low viral load samples which would normally pose a challenge for metagenomic sequencing.

High-resolution epitope mapping and characterization of SARS-CoV-2 antibodies in large cohorts of subjects with COVID-19

As Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to spread, characterization of its antibody epitopes, emerging strains, related coronaviruses, and even the human proteome in naturally infected patients can guide the development of effective vaccines and therapies. Since traditional epitope identification tools are dependent upon pre-defined peptide sequences, they are not readily adaptable to diverse viral proteomes. The Serum Epitope Repertoire Analysis (SERA) platform leverages a high diversity random bacterial display library to identify proteome-independent epitope binding specificities which are then analyzed in the context of organisms of interest. When evaluating immune response in the context of SARS-CoV-2, we identify dominant epitope regions and motifs which demonstrate potential to classify mild from severe disease and relate to neutralization activity. We highlight SARS-CoV-2 epitopes that are cross-reactive with other coronaviruses and demonstrate decreased epitope signal for mutant SARS-CoV-2 strains. Collectively, the evolution of SARS-CoV-2 mutants towards reduced antibody response highlight the importance of data-driven development of the vaccines and therapies to treat COVID-19.

Using a high throughput, random bacterial peptide display approach applied to patient serum samples, Haynes, Kamath, Bozekowski et al identify the antigens and epitopes that elicit a SARS-CoV-2 humoral response. They identify differences depending on disease severity and further in silico analysis suggests decreased epitope signal for Q677P but not for D614G mutant SARSCoV-2 strains.

SARS-COV-2 Delta variant displays moderate resistance to neutralizing antibodies and spike protein properties of higher soluble ACE2 sensitivity, enhanced cleavage and fusogenic activity

The SARS-CoV-2 B.1.617 lineage variants, Kappa (B.1.617.1) and Delta (B.1.617.2, AY) emerged during the second wave of infections in India, but the Delta variants have become dominant worldwide and continue to evolve. The spike proteins of B.1.617.1, B.1.617.2, and AY.1 variants have several substitutions in the receptor binding domain (RBD), including L452R+E484Q, L452R+T478K, and K417N+L452R+T478K, respectively, that could potentially reduce effectiveness of therapeutic antibodies and current vaccines. Here we compared B.1.617 variants, and their single and double RBD substitutions for resistance to neutralization by convalescent sera, mRNA vaccine-elicited sera, and therapeutic neutralizing antibodies using a pseudovirus neutralization assay. Pseudoviruses with the B.1.617.1, B.1.617.2, and AY.1 spike showed a modest 1.5 to 4.4-fold reduction in neutralization titer by convalescent sera and vaccine-elicited sera. In comparison, similar modest reductions were also observed for pseudoviruses with C.37, P.1, R.1, and B.1.526 spikes, but seven- and sixteen-fold reduction for vaccine-elicited and convalescent sera, respectively, was seen for pseudoviruses with the B.1.351 spike. Four of twenty-three therapeutic neutralizing antibodies showed either complete or partial loss of neutralization against B.1.617.2 pseudoviruses due to the L452R substitution, whereas six of twenty-three therapeutic neutralizing antibodies showed either complete or partial loss of neutralization against B.1.617.1 pseudoviruses due to either the E484Q or L452R substitution. Against AY.1 pseudoviruses, the L452R and K417N substitutions accounted for the loss of neutralization by four antibodies and one antibody, respectively, whereas one antibody lost potency that could not be fully accounted for by a single RBD substitution. The modest resistance of B.1.617 variants to vaccine-elicited sera suggest that current mRNA-based vaccines will likely remain effective in protecting against B.1.617 variants, but the therapeutic antibodies need to be carefully selected based on their resistance profiles. Finally, the spike proteins of B.1.617 variants are more efficiently cleaved due to the P681R substitution, and the spike of Delta variants exhibited greater sensitivity to soluble ACE2 neutralization, as well as fusogenic activity, which may contribute to enhanced spread of Delta variants.

Circulation and Evolution of SARS-CoV-2 in India: Let the Data Speak

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.

Neutralization of SARS-CoV-2 Variants of Concern Harboring Q677H

The sensitivity of SARS-CoV-2 variants of concern (VOCs) to neutralizing antibodies has largely been studied in the context of key receptor binding domain (RBD) mutations, including E484K and N501Y. Little is known about the epistatic effects of combined SARS-CoV-2 spike mutations. We now investigate the neutralization sensitivity of variants containing the non-RBD mutation Q677H, including B.1.525 (Nigerian isolate) and Bluebird (U.S. isolate) variants. The effect on neutralization of Q677H was determined in the context of the RBD mutations and in the background of major VOCs, including B.1.1.7 (United Kingdom, Alpha), B.1.351 (South Africa, Beta), and P1-501Y-V3 (Brazil, Gamma). We demonstrate that the Q677H mutation increases viral infectivity and syncytium formation, as well as enhancing resistance to neutralization for VOCs, including B.1.1.7 and P1-501Y-V3. Our work highlights the importance of epistatic interactions between SARS-CoV-2 spike mutations and the continued need to monitor Q677H-bearing VOCs.

SARS-CoV-2: Current trends in emerging variants, pathogenesis, immune responses, potential therapeutic, and vaccine development strategies

More than a year after the SARS-CoV-2 pandemic, the Coronavirus disease 19 (COVID-19) is still a major global challenge for scientists to understand the different dimensions of infection and find ways to prevent, treat, and develop a vaccine. On January 30, 2020, the world health organization (WHO) officially announced this new virus as an international health emergency. While many biological and mechanisms of pathogenicity of this virus are still unclear, it seems that cytokine storm resulting from an immune response against the virus is considered the main culprit of the severity of the disease. Despite many global efforts to control the SARS-CoV-2, several problems and challenges have been posed in controlling the COVID-19 infection. These problems include the various mutations, the emergence of variants with high transmissibility, the short period of immunity against the virus, the possibility of reinfection in people improved, lack of specific drugs, and problems in the development of highly sensitive and specific vaccines. In this review, we summarized the results of the current trend and the latest research studies on the characteristics of the structure and genome of the SARS-CoV- 2, new mutations and variants of SARS-CoV-2, pathogenicity, immune response, virus diagnostic tests, potential treatment, and vaccine candidate.

Emergence and Spread of a B.1.1.28-Derived P.6 Lineage with Q675H and Q677H Spike Mutations in Uruguay

Uruguay controlled the viral dissemination during the first nine months of the SARS-CoV-2 pandemic. Unfortunately, towards the end of 2020, the number of daily new cases exponentially increased. Herein, we analyzed the country-wide genetic diversity of SARS-CoV-2 between November 2020 and April 2021. We identified that the most prevalent viral variant during the first epidemic wave in Uruguay (December 2020-February 2021) was a B.1.1.28 sublineage carrying Spike mutations Q675H + Q677H, now designated as P.6, followed by lineages P.2 and P.7. P.6 probably arose around November 2020, in Montevideo, Uruguay's capital department, and rapidly spread to other departments, with evidence of further local transmission clusters; it also spread sporadically to the USA and Spain. The more efficient dissemination of lineage P.6 with respect to P.2 and P.7 and the presence of mutations (Q675H and Q677H) in the proximity of the key cleavage site at the S1/S2 boundary suggest that P.6 may be more transmissible than other lineages co-circulating in Uruguay. Although P.6 was replaced by the variant of concern (VOC) P.1 as the predominant lineage in Uruguay since April 2021, the monitoring of the concurrent emergence of Q675H + Q677H in VOCs should be of worldwide interest.

Handheld Thermo-Photonic Device for Rapid, Low-Cost, and On-Site Detection and Quantification of Anti-SARS-CoV-2 Antibody

With the emergence of vaccines and antibody therapeutics, rapid and scalable platforms are needed to quantify the antibody response of individuals. Lateral flow immunoassay (LFA) based test strips provide a rapid, low-cost, and point-of-care approach to antibody testing against the SARS-CoV-2 virus. These convenient and scalable tests, however, are qualitative in nature and cannot quantify the immune response of the infected and/or vaccinated individuals. This study reports on the development of a rapid, low cost and portable thermo-photonic device that enables sensitive detection and quantification of antibody levels using commercially available COVID-19 Antibody LFAs. Unlike conventional LFA readers, the developed technology is based on sensing the infrared thermal radiation of tag gold nanoparticles following laser excitation (aka photothermal response). Our proof-of-concept results with humanized monoclonal anti-SARS-CoV-2 Spike receptor-binding domain (RBD) IgG demonstrate that the thermo-photonic technology can detect and quantify antibody concentrations within the clinically relevant range and with a limit of detection of [Formula: see text]/ml. The reader in conjunction with antibody LFAs offers a low-cost, portable, and scalable solution for assessment of the degree of immunity in populations, quality control of convalescent plasma donations for antibody therapeutics, and monitoring the immune response of infected individuals and vaccine recipients.

Holiday gatherings, mobility and SARS-CoV-2 transmission: results from 10 US states following Thanksgiving

Public health officials discouraged travel and non-household gatherings for Thanksgiving, but data suggests that travel increased over the holidays. The objective of this analysis was to assess associations between holiday gatherings and SARS-CoV-2 positivity in the weeks following Thanksgiving. Using an online survey, we sampled 7770 individuals across 10 US states from December 4-18, 2020, about 8-22 days post-Thanksgiving. Participants were asked about Thanksgiving, COVID-19 symptoms, and SARS-CoV-2 testing and positivity in the prior 2 weeks. Logistic regression was used to identify factors associated with SARS-CoV-2 positivity and COVID-19 symptoms in the weeks following Thanksgiving. An activity score measured the total number of non-essential activities an individual participated in the prior 2 weeks. The probability of community transmission was estimated using Markov Chain Monte Carlo (MCMC) methods. While 47.2% had Thanksgiving at home with household members, 26.9% had guests and 25.9% traveled. There was a statistically significant interaction between how people spent Thanksgiving, the frequency of activities, and SARS-CoV-2 test positivity in the prior 2 weeks (p < 0.05). Those who had guests for Thanksgiving or traveled were only more likely to test positive for SARS-CoV-2 if they also had high activity (e.g., participated in > one non-essential activity/day in the prior 2 weeks). Had individuals limited the number and frequency of activities post-Thanksgiving, cases in surveyed individuals would be reduced by > 50%. As travel continues to increase and the more contagious Delta variant starts to dominate transmission, it is critical to promote how to gather in a "low-risk" manner (e.g., minimize other non-essential activities) to mitigate the need for nationwide shelter-at-home orders.

Evolutionary trajectory of SARS-CoV-2 and emerging variants

The emergence of a novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and more recently, the independent evolution of multiple SARS-CoV-2 variants has generated renewed interest in virus evolution and cross-species transmission. While all known human coronaviruses (HCoVs) are speculated to have originated in animals, very little is known about their evolutionary history and factors that enable some CoVs to co-exist with humans as low pathogenic and endemic infections (HCoV-229E, HCoV-NL63, HCoV-OC43, HCoV-HKU1), while others, such as SARS-CoV, MERS-CoV and SARS-CoV-2 have evolved to cause severe disease. In this review, we highlight the origins of all known HCoVs and map positively selected for mutations within HCoV proteins to discuss the evolutionary trajectory of SARS-CoV-2. Furthermore, we discuss emerging mutations within SARS-CoV-2 and variants of concern (VOC), along with highlighting the demonstrated or speculated impact of these mutations on virus transmission, pathogenicity, and neutralization by natural or vaccine-mediated immunity.

A Possible Role of Remdesivir and Plasma Therapy in the Selective Sweep and Emergence of New SARS-CoV-2 Variants

Since summer 2020, SARS-CoV-2 strains at the origin of the COVID-19 pandemic have suddenly been replaced by new SARS-CoV-2 variants, some of which are highly transmissible and spread at a high rate. These variants include the Marseille-4 lineage (Nextclade 20A.EU2) in Europe, the 20I/501Y.V1 variant first detected in the UK, the 20H/501Y.V2 variant first detected in South Africa, and the 20J/501Y.V3 variant first detected in Brazil. These variants are characterized by multiple mutations in the viral spike protein that is targeted by neutralizing antibodies elicited in response to infection or vaccine immunization. The usual coronavirus mutation rate through genetic drift alone cannot account for such rapid changes. Recent reports of the occurrence of such mutations in immunocompromised patients who received remdesivir and/or convalescent plasma or monoclonal antibodies to treat prolonged SARS-CoV-2 infections led us to hypothesize that experimental therapies that fail to cure the patients from COVID-19 could favor the emergence of immune escape SARS-CoV-2 variants. We review here the data that support this hypothesis and urge physicians and clinical trial promoters to systematically monitor viral mutations by whole-genome sequencing for patients who are administered these treatments.

SARS-CoV-2 variants, spike mutations and immune escape

Although most mutations in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome are expected to be either deleterious and swiftly purged or relatively neutral, a small proportion will affect functional properties and may alter infectivity, disease severity or interactions with host immunity. The emergence of SARS-CoV-2 in late 2019 was followed by a period of relative evolutionary stasis lasting about 11 months. Since late 2020, however, SARS-CoV-2 evolution has been characterized by the emergence of sets of mutations, in the context of 'variants of concern', that impact virus characteristics, including transmissibility and antigenicity, probably in response to the changing immune profile of the human population. There is emerging evidence of reduced neutralization of some SARS-CoV-2 variants by postvaccination serum; however, a greater understanding of correlates of protection is required to evaluate how this may impact vaccine effectiveness. Nonetheless, manufacturers are preparing platforms for a possible update of vaccine sequences, and it is crucial that surveillance of genetic and antigenic changes in the global virus population is done alongside experiments to elucidate the phenotypic impacts of mutations. In this Review, we summarize the literature on mutations of the SARS-CoV-2 spike protein, the primary antigen, focusing on their impacts on antigenicity and contextualizing them in the protein structure, and discuss them in the context of observed mutation frequencies in global sequence datasets.

SARS-CoV-2 variants, spike mutations and immune escape

Although most mutations in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome are expected to be either deleterious and swiftly purged or relatively neutral, a small proportion will affect functional properties and may alter infectivity, disease severity or interactions with host immunity. The emergence of SARS-CoV-2 in late 2019 was followed by a period of relative evolutionary stasis lasting about 11 months. Since late 2020, however, SARS-CoV-2 evolution has been characterized by the emergence of sets of mutations, in the context of 'variants of concern', that impact virus characteristics, including transmissibility and antigenicity, probably in response to the changing immune profile of the human population. There is emerging evidence of reduced neutralization of some SARS-CoV-2 variants by postvaccination serum; however, a greater understanding of correlates of protection is required to evaluate how this may impact vaccine effectiveness. Nonetheless, manufacturers are preparing platforms for a possible update of vaccine sequences, and it is crucial that surveillance of genetic and antigenic changes in the global virus population is done alongside experiments to elucidate the phenotypic impacts of mutations. In this Review, we summarize the literature on mutations of the SARS-CoV-2 spike protein, the primary antigen, focusing on their impacts on antigenicity and contextualizing them in the protein structure, and discuss them in the context of observed mutation frequencies in global sequence datasets.

SARS-CoV-2 Portrayed against HIV: Contrary Viral Strategies in Similar Disguise

SARS-CoV-2 and HIV are zoonotic viruses that rapidly reached pandemic scale, causing global losses and fear. The COVID-19 and AIDS pandemics ignited massive efforts worldwide to develop antiviral strategies and characterize viral architectures, biological and immunological properties, and clinical outcomes. Although both viruses have a comparable appearance as enveloped viruses with positive-stranded RNA and envelope spikes mediating cellular entry, the entry process, downstream biological and immunological pathways, clinical outcomes, and disease courses are strikingly different. This review provides a systemic comparison of both viruses' structural and functional characteristics, delineating their distinct strategies for efficient spread.