Global Prevalence of Adaptive and Prolonged Infections' Mutations in the Receptor-Binding Domain of the SARS-CoV-2 Spike Protein

Persistence of SARS-CoV-2 infection and viral intra- and inter-host evolution in COVID-19 hospitalized patients

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) persistence in COVID-19 patients could play a key role in the emergence of variants of concern. The rapid intra-host evolution of SARS-CoV-2 may result in an increased transmissibility, immune and therapeutic escape which could be a direct consequence of COVID-19 epidemic currents. In this context, a longitudinal retrospective study on eight consecutive COVID-19 patients with persistent SARS-CoV-2 infection, from January 2022 to March 2023, was conducted. To characterize the intra- and inter-host viral evolution, whole genome sequencing and phylogenetic analysis were performed on nasopharyngeal samples collected at different time points. Phylogenetic reconstruction revealed an accelerated SARS-CoV-2 intra-host evolution and emergence of antigenically divergent variants. The Bayesian inference and principal coordinate analysis analysis showed a host-based genomic structuring among antigenically divergent variants, that might reflect the positive effect of containment practices, within the critical hospital area. All longitudinal antigenically divergent isolates shared a wide range of amino acidic (aa) changes, particularly in the Spike (S) glycoprotein, that increased viral transmissibility (K417N, S477N, N501Y and Q498R), enhanced infectivity (R346T, S373P, R408S, T478K, Q498R, Y505H, D614G, H655Y, N679K and P681H), caused host immune escape (S371L, S375F, T376A, K417N, and K444T/R) and displayed partial or complete resistance to treatments (G339D, R346K/T, S371F/L, S375F, T376A, D405N, N440K, G446S, N460K, E484A, F486V, Q493R, G496S and Q498R). These results suggest that multiple novel variants which emerge in the patient during persistent infection, might spread to another individual and continue to evolve. A pro-active genomic surveillance of persistent SARS-CoV-2 infected patients is recommended to identify genetically divergent lineages before their diffusion.

Cell type-specific adaptation of the SARS-CoV-2 spike

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) can infect various human tissues and cell types, principally via interaction with its cognate receptor angiotensin-converting enzyme-2 (ACE2). However, how the virus evolves in different cellular environments is poorly understood. Here, we used experimental evolution to study the adaptation of the SARS-CoV-2 spike to four human cell lines expressing different levels of key entry factors. After twenty passages of a spike-expressing recombinant vesicular stomatitis virus (VSV), cell-type-specific phenotypic changes were observed and sequencing allowed the identification of sixteen adaptive spike mutations. We used VSV pseudotyping to measure the entry efficiency, ACE2 affinity, spike processing, TMPRSS2 usage, and entry pathway usage of all the mutants, alone or in combination. The fusogenicity of the mutant spikes was assessed with a cell-cell fusion assay. Finally, mutant recombinant VSVs were used to measure the fitness advantage associated with selected mutations. We found that the effects of these mutations varied across cell types, both in terms of viral entry and replicative fitness. Interestingly, two spike mutations (L48S and A372T) that emerged in cells expressing low ACE2 levels increased receptor affinity, syncytia induction, and entry efficiency under low-ACE2 conditions. Our results demonstrate specific adaptation of the SARS-CoV-2 spike to different cell types and have implications for understanding SARS-CoV-2 tissue tropism and evolution.

Prevalence of SARS-CoV-2 Omicron Sublineages and Spike Protein Mutations Conferring Resistance against Monoclonal Antibodies in a Swedish Cohort during 2022-2023

Monoclonal antibodies (mAbs) are an important treatment option for COVID-19 caused by SARS-CoV-2, especially in immunosuppressed patients. However, this treatment option can become ineffective due to mutations in the SARS-CoV-2 genome, mainly in the receptor binding domain (RBD) of the spike (S) protein. In the present study, 7950 SARS-CoV-2 positive samples from the Uppsala and Örebro regions of central Sweden, collected between March 2022 and May 2023, were whole-genome sequenced using amplicon-based sequencing methods on Oxford Nanopore GridION, Illumina MiSeq, Illumina HiSeq, or MGI DNBSEQ-G400 instruments. Pango lineages were determined and all single nucleotide polymorphism (SNP) mutations that occurred in these samples were identified. We found that the dominant sublineages changed over time, and mutations conferring resistance to currently available mAbs became common. Notable ones are R346T and K444T mutations in the RBD that confer significant resistance against tixagevimab and cilgavimab mAbs. Further, mutations conferring a high-fold resistance to bebtelovimab, such as the K444T and V445P mutations, were also observed in the samples. This study highlights that resistance mutations have over time rendered currently available mAbs ineffective against SARS-CoV-2 in most patients. Therefore, there is a need for continued surveillance of resistance mutations and the development of new mAbs that target more conserved regions of the RBD.

COVID-19 Vaccine Knowledge, Attitudes, and Practices in Alabama: The Case for Primary Health Care Providers

OBJECTIVE

To examine knowledge, attitudes, and practices about COVID-19 in Alabama, with a primary focus on vaccination perception and utilization.

DESIGN

We used a COVID-19 Knowledge, Attitudes, and Practices survey and recruited adult Alabama residents in April-May 2021.

PARTICIPANTS

Initial surveys from 1324 Alabamian participants were considered for analysis; after careful review of incomplete responses, 953 were ultimately included for analysis.

MAIN OUTCOME MEASURE

Vaccine behavior and hesitancy comprise a self-reported response contained in the survey instrument. Three primary vaccine groups were used to assess differences in demographic characteristics, health status, perception of susceptibility and severity of COVID-19, sources of information, and trust about COVID-19.

RESULTS

Of the 953 survey participants included for analysis, 951 had self-identified vaccine status in which 153 (16.1%) reported to have received the vaccine at the time of the survey, 375 (39.4%) were very likely or somewhat likely to get an approved COVID-19 vaccine if it was offered, and 423 (44.5%) were somewhat unlikely or very unlikely to get an approved COVID-19 vaccine. Health care providers were the most trusted sources of information, regardless of vaccine status. For participants unlikely to receive a vaccine, social media and local news sources were consistently more trusted and utilized than those who were vaccinated or were likely to be.

CONCLUSIONS

The perceptions among unvaccinated participants are actionable and provide teachable opportunities to decrease vaccine apprehension.

Lessons learned and implications of early therapies for coronavirus disease in a territorial service centre in the Calabria region: a retrospective study

Background

Monoclonal antibodies (mAbs) and antivirals have been approved for early therapy of coronavirus disease (COVID-19), however, in the real-life setting, there are difficulties to prescribe these therapies within few days from symptom onset as recommended, and effectiveness of combined use of these drugs have been hypothesised in most-at-risk patients (such as those immunocompromised) but data supporting this strategy are limited.

Methods

We describe the real-life experience of SARS-CoV-2 antivirals and/or monoclonal antibodies (mAbs) and focus on the hospitalisation rate due to the progression of COVID-19. Clinical results obtained through our risk-stratification algorithm and benefits achieved through a strategic proximity territorial centre are provided. We also report a case series with an in-depth evaluation of SARS-CoV-2 genome in relationship with treatment strategy and clinical evolution of patients.

Results

Two hundred eighty-eight patients were analysed; 94/288 (32.6%) patients were treated with mAb monotherapy, 171/288 (59.4%) patients were treated with antivirals, and 23/288 (8%) patients received both mAbs and one antiviral drug. Haematological malignancies were more frequent in patients treated with combination therapy than in the other groups (p = 0.0003). There was a substantial increase in the number of treated patients since the opening of the centre dedicated to early therapies for COVID-19. The provided disease-management and treatment appeared to be effective since 98.6% patients recovered without hospital admission. Moreover, combination therapy with mAbs and antivirals seemed successful because all patients admitted to the hospital for COVID-19 did not receive such therapies, while none of the most-at-risk patients treated with combination therapy were hospitalized or reported adverse events.

Conclusions

A low rate of COVID-19 progression requiring hospital admission was observed in patients included in this study. The dedicated COVID-19 proximity territorial service appeared to strengthen the regional sanitary system, avoiding the overwhelming of other services. Importantly, our results also support early combination therapy: it is possible that this strategy reduces the emergence of escape mutants of SARS-CoV-2, thereby increasing efficacy of early treatment, especially in immunocompromised individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-022-07774-9.

SARS-CoV-2 variants of concern and spike protein mutational dynamics in a Swedish cohort during 2021, studied by Nanopore sequencing

BACKGROUND

Since the beginning of the COVID-19 pandemic, new variants of significance to public health have emerged. Consequently, early detection of new mutations and variants through whole-genome sequencing remains crucial to assist health officials in employing appropriate public health measures.

METHODS

We utilized the ARTIC Network SARS-CoV-2 tiled amplicon approach and Nanopore sequencing to sequence 4,674 COVID-19 positive patient samples from Uppsala County, Sweden, between week 15 and 52 in 2021. Using this data, we mapped the circulating variants of concern (VOC) in the county over time and analysed the Spike (S) protein mutational dynamics in the Delta variant throughout 2021.

RESULTS

The distribution of the SARS-CoV-2 VOC matched the national VOC distribution in Sweden, in 2021. In the S protein of the Delta variant, we detected mutations attributable to variants under monitoring and variants of interest (e.g., E484Q, Q613H, Q677H, A222V and Y145H) and future VOC (e.g., T95I and Y144 deletion, which are signature mutations in the Omicron variant). We also frequently detected some less well-described S protein mutations in our Delta sequences, that might play a role in shaping future emerging variants. These include A262S, Q675K, I850L, Q1201H, V1228L and M1237I. Lastly, we observed that some of the Delta variant's signature mutations were underrepresented in our study due to artifacts of the used bioinformatics tools, approach and sequencing method. We therefore discuss some pitfalls and considerations when sequencing SARS-CoV-2 genomes.

CONCLUSION

Our results suggest that genomic surveillance in a small, representative cohort can be used to make predictions about the circulating variants nationally. Moreover, we show that detection of transient mutations in currently circulating variants can give valuable clues to signature mutations of future VOC. Here we suggest six such mutations, that we detected frequently in the Delta variant during 2021. Lastly, we report multiple systematic errors that occurred when following the ARTIC Network SARS-CoV-2 tiled amplicon approach using the V3 primers and Nanopore sequencing, which led to the masking of some of the important signature mutations in the Delta sequences.

Spike protein of SARS-CoV-2 variants: a brief review and practical implications

The scientific community has been alarmed by the possible immunological evasion, higher infectivity, and severity of disease caused by the newest variants of SARS-CoV-2. The spike protein has an important role in the cellular invasion of viruses and is the target of several vaccines and therapeutic resources, such as monoclonal antibodies. In addition, some of the most relevant mutations in the different variants are on the spike (S) protein gene sequence that leads to structural alterations in the predicted protein, thus causing concern about the protection mediated by vaccines against these new strains. The present review highlights the most recent knowledge about COVID-19 and vaccines, emphasizing the different spike protein structures of SARS-CoV-2 and updating the reader about the emerging viral variants and their classifications, the more common viral mutations described and their distribution in Brazil. It also compiles a table with the most recent knowledge about all of the Omicron spike mutations.

Dynamics of the interaction between the receptor-binding domain of SARS-CoV-2 Omicron (B.1.1.529) variant and human angiotensin-converting enzyme 2

Background

The COVID-19 pandemic is still a global public health issue. Omicron, a SARS-CoV-2 B.1.1.529 variant, has raised concerns about transmission and vaccine effectiveness. Omicron currently has the greatest number of variantions.

Methods

To gain a better understanding of the significance of these variations and the dynamics of the interaction between the Omicron spike (S) protein and its human host factor angiotensin-converting enzyme 2 (ACE2), triplicate 500 ns molecular dynamics simulations were run using the structure of the S protein's receptor-binding domain (RBD) in complex with ACE2. The interaction and binding energy, determined using the molecular mechanics-generalized Born surface area approach, were compared to the original SARS-CoV-2 and the B.1.617 variant.

Results

Though mutations K417N and G496S in the S protein RBD disrupt interactions found in the original SARS-CoV-2 complex, mutations Q493R and N501Y introduce interactions not found in the original complex. Interaction at a key viral hotspot and hydrophobic contacts at ACE2's N-terminus were preserved, but intermolecular hydrogen bonds and polar contacts in the S-ACE2 interface were lower than in the original SARS-CoV-2 interface.

Establishment of a pseudovirus neutralization assay based on SARS-CoV-2 S protein incorporated into lentiviral particles

The Coronavirus Disease 2019 (COVID-19) is still causing a wide range of infections and deaths due to the high variability of the SARS-CoV-2 virus. Therefore, it is necessary to establish a reliable and convenient pseudovirus-based neutralization assay to develop drug targeted variants of SARS-CoV-2. Based on the HIV-1 backbone, we generated a high titer luciferase (Luc)-expressing pseudovirus packaging system. Three dominant S mutant substitution pseudovirus were also established and identified compared to wide type in hACE2-overexpressing HEK-293T cells (293T-ACE2 cells). Compared to serine protease inhibitor camostat mesylate, the cysteine protease inhibitor E-64d could significantly block all SARS-CoV-2 mutant S pseudovirus infection in 293T-ACE2 cells. Furthermore, the neutralization ability of two antibodies targeted receptor-binding domain (RBD) of SARS-CoV-2 spike protein (S) was evaluated, which showed different inhibition dose-effect curves among four types of S pseudovirus. Overall, we developed a pseudovirus-based neutralization assay for SARS-CoV-2, which would be readily adapted to SARS-CoV-2 variants for evaluating antibodies.

COVID-19 in 2021

The Special Issue on Vaccines and Therapeutics against Coronaviruses, which was launched in early 2021, has attracted the scientific community at large, and more than 20 manuscripts have been accepted for publication.[...].