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1.
Int J Mol Sci ; 23(14)2022 Jul 12.
Article in English | MEDLINE | ID: covidwho-1928575

ABSTRACT

SARS-CoV-2 variants raise concern because of their high transmissibility and their ability to evade neutralizing antibodies elicited by prior infection or by vaccination. Here, we compared the neutralizing abilities of sera from 70 unvaccinated COVID-19 patients infected before the emergence of variants of concern (VOCs) and of 16 vaccine breakthrough infection (BTI) cases infected with Gamma or Delta against the ancestral B.1 strain, the Gamma, Delta and Omicron BA.1 VOCs using live virus. We further determined antibody levels against the Nucleocapsid (N) and full Spike proteins, the receptor-binding domain (RBD) and the N-terminal domain (NTD) of the Spike protein. Convalescent sera featured considerable variability in the neutralization of B.1 and in the cross-neutralization of different strains. Their neutralizing capacity moderately correlated with antibody levels against the Spike protein and the RBD. All but one convalescent serum failed to neutralize Omicron BA.1. Overall, convalescent sera from patients with moderate disease had higher antibody levels and displayed a higher neutralizing ability against all strains than patients with mild or severe forms of the disease. The sera from BTI cases fell into one of two categories: half the sera had a high neutralizing activity against the ancestral B.1 strain as well as against the infecting strain, while the other half had no or a very low neutralizing activity against all strains. Although antibody levels against the spike protein and the RBD were lower in BTI sera than in unvaccinated convalescent sera, most neutralizing sera also retained partial neutralizing activity against Omicron BA.1, suggestive of a better cross-neutralization and higher affinity of vaccine-elicited antibodies over virus-induced antibodies. Accordingly, the IC50: antibody level ratios were comparable for BTI and convalescent sera, but remained lower in the neutralizing convalescent sera from patients with moderate disease than in BTI sera. The neutralizing activity of BTI sera was strongly correlated with antibodies against the Spike protein and the RBD. Together, these findings highlight qualitative differences in antibody responses elicited by infection in vaccinated and unvaccinated individuals. They further indicate that breakthrough infection with a pre-Omicron variant boosts immunity and induces cross-neutralizing antibodies against different strains, including Omicron BA.1.


Subject(s)
COVID-19 , Vaccines , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19/therapy , Humans , Immunization, Passive , Neutralization Tests , SARS-CoV-2 , Spike Glycoprotein, Coronavirus
2.
Cell Rep Methods ; 2(7): 100252, 2022 Jul 18.
Article in English | MEDLINE | ID: covidwho-1894918

ABSTRACT

Efficient quantitative assays for measurement of viral replication and infectivity are indispensable for future endeavors to develop prophylactic or therapeutic antiviral drugs or vaccines against SARS-CoV-2. We developed a SARS-CoV-2 cell-cell transmission assay that provides a rapid and quantitative readout to assess SARS-CoV-2 spike hACE2 interaction in the absence of pseudotyped particles or live virus. We established two well-behaved stable cell lines, which demonstrated a remarkable correlation with standard cell-free viral pseudotyping for inhibition by convalescent sera, small-molecule drugs, and murine anti-spike monoclonal antibodies. The assay is rapid, reliable, and highly reproducible, without a requirement for any specialized research reagents or laboratory equipment and should be easy to adapt for use in most investigative and clinical settings. It can be effectively used or modified for high-throughput screening for compounds and biologics that interfere with virus-cell binding and entry to complement other neutralization assays currently in use.

3.
Viruses ; 14(2)2022 02 17.
Article in English | MEDLINE | ID: covidwho-1705787

ABSTRACT

In light of an increasing number of vaccinated and convalescent individuals, there is a major need for the development of robust methods for the quantification of neutralizing antibodies; although, a defined correlate of protection is still missing. Sera from hospitalized COVID-19 patients suffering or not suffering from acute respiratory distress syndrome (ARDS) were comparatively analyzed by plaque reduction neutralization test (PRNT) and pseudotype-based neutralization assays to quantify their neutralizing capacity. The two neutralization assays showed comparable data. In case of the non-ARDS sera, there was a distinct correlation between the data from the neutralization assays on the one hand, and enzyme-linked immune sorbent assay (ELISA), as well as biophysical analyses, on the other hand. As such, surface plasmon resonance (SPR)-based assays for quantification of binding antibodies or analysis of the stability of the antigen-antibody interaction and inhibition of syncytium formation, determined by cell fusion assays, were performed. In the case of ARDS sera, which are characterized by a significantly higher fraction of RBD-binding IgA antibodies, there is a clear correlation between the neutralization assays and the ELISA data. In contrast to this, a less clear correlation between the biophysical analyses on the one hand and ELISAs and neutralization assays on the other hand was observed, which might be explained by the heterogeneity of the antibodies. To conclude, for less complex immune sera-as in cases of non-ARDS sera-combinations of titer quantification by ELISA with inhibition of syncytium formation, SPR-based analysis of antibody binding, determination of the stability of the antigen-antibody complex, and competition of the RBD-ACE2 binding represent alternatives to the classic PRNT for analysis of the neutralizing potential of SARS-CoV-2-specific sera, without the requirement for a BSL3 facility.


Subject(s)
Antibodies, Viral/blood , Convalescence , Immune Sera/analysis , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/blood , Spike Glycoprotein, Coronavirus/immunology , Adult , Aged , Aged, 80 and over , Antibodies, Neutralizing/immunology , COVID-19/immunology , Enzyme-Linked Immunosorbent Assay , Female , Hospitalization/statistics & numerical data , Humans , Immune Sera/immunology , Immunity, Humoral , Male , Middle Aged , Neutralization Tests
4.
Infect Drug Resist ; 15: 373-385, 2022.
Article in English | MEDLINE | ID: covidwho-1686263

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spread rapidly over the world and claimed million lives. The virus evolves constantly, and a swarm of mutants is a now major concern globally. Distinct variants could have independently converged on same mutation, despite being detected in different geographic regions, which suggested it could confer an evolutionary advantage. E484K has rapidly emerged and has frequently been detected in several SARS-CoV-2 variants of concern. In this study, we review the epidemiology and impact of E484K, its effects on neutralizing effect of several monoclonal antibodies, convalescent plasma, and post-vaccine sera.

5.
Front Immunol ; 12: 751584, 2021.
Article in English | MEDLINE | ID: covidwho-1463475

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a global pandemic of novel coronavirus disease (COVID-19). Though vaccines and neutralizing monoclonal antibodies (mAbs) have been developed to fight COVID-19 in the past year, one major concern is the emergence of SARS-CoV-2 variants of concern (VOCs). Indeed, SARS-CoV-2 VOCs such as B.1.1.7 (UK), B.1.351 (South Africa), P.1 (Brazil), and B.1.617.1 (India) now dominate the pandemic. Herein, we found that binding activity and neutralizing capacity of sera collected from convalescent patients in early 2020 for SARS-CoV-2 VOCs, but not non-VOC variants, were severely blunted. Furthermore, we observed evasion of SARS-CoV-2 VOCs from a VH3-30 mAb 32D4, which was proved to exhibit highly potential neutralization against wild-type (WT) SARS-CoV-2. Thus, these results indicated that SARS-CoV-2 VOCs might be able to spread in convalescent patients and even harbor resistance to medical countermeasures. New interventions against these SARS-CoV-2 VOCs are urgently needed.


Subject(s)
COVID-19/immunology , Mutation/genetics , SARS-CoV-2/physiology , Adult , Antibodies, Monoclonal/metabolism , Antibodies, Neutralizing/metabolism , Antibodies, Viral/metabolism , COVID-19/genetics , COVID-19/therapy , Female , Humans , Immune Evasion , Immunization, Passive , Male , Middle Aged , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
6.
J Clin Virol Plus ; 1(3): 100038, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1364220

ABSTRACT

SARS-CoV-2-specific IgM antibodies wane during the first three months after infection and IgG antibody levels decline. This may limit the ability of antibody tests to identify previous SARS-CoV-2 infection at later time points. To examine if the diagnostic sensitivity of antibody tests falls off, we compared the sensitivity of two nucleoprotein-based antibody tests, the Roche Elecsis II Anti-SARS-CoV-2 and the Abbott SARS-CoV-2 IgG assay and three glycoprotein-based tests, the Abbott SARS-CoV-2 IgG II Quant, Siemens Atellica IM COV2T and Euroimmun SARS-CoV-2 assay with 53 sera obtained 6 months after SARS-CoV-2 infection. The sensitivity of the Roche, Abbott SARS-CoV-2 IgG II Quant and Siemens antibody assays was 94.3% (95% confidence interval (CI) 84.3-98.8%), 98.1 % (95% CI: 89.9-100%) and 100 % (95% CI: 93.3-100%). The sensitivity of the N-based Abbott SARS-CoV-2 IgG and the glycoprotein-based Euroimmun ELISA was 45.3 % (95% CI: 31.6-59.6%) and 83.3% (95% CI: 70.2-91.9%). The nucleoprotein-based Roche and the glycoprotein-based Abbott receptor binding domain (RBD) and Siemens tests were more sensitive than the N-based Abbott and the Euroimmun antibody tests (p = 0.0001 to p = 0.039). The N-based Abbott antibody test was less sensitive 6 months than 4-10 weeks after SARS-CoV-2 infection (p = 0.0001). The findings show that most SARS-CoV-2 antibody assays correctly identified previous infection 6 months after infection. The sensitivity of pan-Ig antibody tests was not reduced at 6 months when IgM antibodies have usually disappeared. However, one of the nucleoprotein-based antibody tests significantly lost diagnostic sensitivity over time.

7.
Front Cell Infect Microbiol ; 11: 644574, 2021.
Article in English | MEDLINE | ID: covidwho-1207695

ABSTRACT

Vaccines are essential to control the spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and to protect the vulnerable population. However, one safety concern of vaccination is the possible development of antibody-dependent enhancement (ADE) of SARS-CoV-2 infection. The potential infection of Fc receptor bearing cells such as macrophages, would support continued virus replication and inflammatory responses, and thereby potentially worsen the clinical outcome of COVID-19. Here we demonstrate that SARS-CoV-2 and SARS-CoV neither infect human monocyte-derived macrophages (hMDM) nor induce inflammatory cytokines in these cells, in sharp contrast to Middle East respiratory syndrome (MERS) coronavirus and the common cold human coronavirus 229E. Furthermore, serum from convalescent COVID-19 patients neither induced enhancement of SARS-CoV-2 infection nor innate immune response in hMDM. Although, hMDM expressed angiotensin-converting enzyme 2, no or very low levels of transmembrane protease serine 2 were found. These results support the view that ADE may not be involved in the immunopathological processes associated with COVID-19, however, more studies are necessary to understand the potential contribution of antibodies-virus complexes with other cells expressing FcR receptors.


Subject(s)
COVID-19 , Middle East Respiratory Syndrome Coronavirus , Antibodies, Viral , Humans , Macrophages , SARS-CoV-2
8.
Cell Host Microbe ; 29(3): 477-488.e4, 2021 03 10.
Article in English | MEDLINE | ID: covidwho-1053270

ABSTRACT

Neutralizing antibodies against the SARS-CoV-2 spike (S) protein are a goal of COVID-19 vaccines and have received emergency use authorization as therapeutics. However, viral escape mutants could compromise efficacy. To define immune-selected mutations in the S protein, we exposed a VSV-eGFP-SARS-CoV-2-S chimeric virus, in which the VSV glycoprotein is replaced with the S protein, to 19 neutralizing monoclonal antibodies (mAbs) against the receptor-binding domain (RBD) and generated 50 different escape mutants. Each mAb had a unique resistance profile, although many shared residues within an epitope of the RBD. Some variants (e.g., S477N) were resistant to neutralization by multiple mAbs, whereas others (e.g., E484K) escaped neutralization by convalescent sera. Additionally, sequential selection identified mutants that escape neutralization by antibody cocktails. Comparing these antibody-mediated mutations with sequence variation in circulating SARS-CoV-2 revealed substitutions that may attenuate neutralizing immune responses in some humans and thus warrant further investigation.


Subject(s)
Antibodies, Monoclonal/blood , Antibodies, Viral/blood , Mutation , Neutralization Tests/methods , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics , Amino Acid Substitution , Angiotensin-Converting Enzyme 2/genetics , Animals , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/pharmacology , Antibodies, Viral/immunology , COVID-19/virology , COVID-19 Vaccines/immunology , Chlorocebus aethiops , Female , Humans , Mice , Mice, Inbred BALB C , Models, Molecular , Protein Binding , Receptors, Virus/metabolism , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
9.
Antib Ther ; 3(3): 212-220, 2020 Jul.
Article in English | MEDLINE | ID: covidwho-712846

ABSTRACT

The whole world is confronting the pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Unfortunately, there is no vaccine to prevent novel coronavirus infection. Besides several experimental drugs, the strong immune responses and convalescent sera are the current two potential options to tackle coronavirus disease 2019 (COVID-19) infection. Innate immune-mediated antiviral responses are initiated by the recognition of viral invasion through pathogen-associated molecular patterns (PAMPs). In coronavirus, the PAMPs are recognized by Toll-like receptors 3 and 7, endosomal ribonucleic acid receptors, RNA in cytosol, and by pattern recognition receptor (RIG-1) in the alveolar cells and site of invasion. Nuclear factor-κB and interferon regulatory transcription factor (IRF3) are activated in response to the above recognition episode and translocate to nucleus. These transcription factors in the nucleus initiate the expression of interferon type 1 and pro-inflammatory cytokine storm, which leads to first line of defense at the site of viral entrance. The effectiveness of innate immune system is greatly relies on type 1 interferons and its cascade, because of their role in the inhibition of viral replication and initiation of adaptive immune responses. The successful interferon type 1 response put down the viral replication and transmission at prompt point. Passive immunization is the administering of antibodies into infected patients, which is taken from recovered individuals. The convalescent sera of the recovered COVID-19 patients are containing antiviral neutralizing antibodies and are used therapeutically for infected individuals by SARS-CoV-2 and for the purpose of prophylaxis in exposed individuals. The convalescent sera is found effective when administered early at the onset of symptoms.

10.
Ther Adv Respir Dis ; 14: 1753466620926853, 2020.
Article in English | MEDLINE | ID: covidwho-354356

ABSTRACT

COVID-19 has grown into a global pandemic that has strained healthcare throughout the world. There is a sense of urgency in finding a cure for this deadly virus. In this study, we reviewed the empiric options used in common practice for COVID-19, based on the literature available online, with an emphasis on human experiences with these treatments on severe acute respiratory syndrome-associated coronavirus (SARS-COV-1) and other viruses. Convalescent blood products are the most promising potential treatment for use in COVID-19. The use of chloroquine or hydroxychloroquine (HCQ), remdesivir, and tocilizumab are some of the other promising potential therapies; however, they are yet to be tested in randomized clinical trials (RCTs). The use of lopinavir-ritonavir did not prove beneficial in a large RCT. The use of corticosteroids should be avoided in COVID-19 pneumonia unless used for other indications, based on the suggestion of harm in patients with SARS-COV-1 and Middle Eastern Respiratory Syndrome (MERS) infection. The reviews of this paper are available via the supplemental material section.


Subject(s)
Coronavirus Infections/drug therapy , Pneumonia, Viral/drug therapy , Antiviral Agents/adverse effects , Antiviral Agents/therapeutic use , COVID-19 , Humans , Pandemics , Randomized Controlled Trials as Topic
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