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1.
iScience ; : 105969, 2023.
Article in English | ScienceDirect | ID: covidwho-2179844

ABSTRACT

Summary The immune responses to SARS-CoV-2 variants in COVID-19 cases are influenced by various factors including pre-existing immunity via vaccination and prior infection. Elucidating the drivers for upgrading neutralizing activity to SARS-CoV-2 in COVID-19 cases with pre-existing immunity will aid in improving COVID-19 booster vaccines with enhanced cross-protection against antigenically distinct variants, including the Omicron sub-lineage BA.4/5. This study revealed that the magnitude and breadth of neutralization activity to SARS-CoV-2 variants after breakthrough infections are determined primarily by upper respiratory viral load and vaccination-infection time interval. Extensive neutralizing breadth, covering even the most antigenically distant BA.4/5, was observed in cases with higher viral load and longer time intervals. Antigenic cartography depicted a critical role of the time interval in expanding the breadth of neutralization to SARS-CoV-2 variants. Our results illustrate the importance of dosing interval optimization as well as antigen design in developing variant-proof booster vaccines.

2.
Nature ; 2022 Nov 02.
Article in English | MEDLINE | ID: covidwho-2096734

ABSTRACT

The BA.2 sublineage of the SARS-CoV-2 Omicron variant has become dominant in most countries around the world; however, the prevalence of BA.4 and BA.5 is increasing rapidly in several regions. BA.2 is less pathogenic in animal models than previously circulating variants of concern (VOC)1-4. Compared with BA.2, however, BA.4 and BA.5 possess additional substitutions in the spike protein, which play a key role in viral entry, raising concerns that the replication capacity and pathogenicity of BA.4 and BA.5 are higher than those of BA.2. Here, we evaluated the replicative ability and pathogenicity of BA.4 and BA.5 isolates in wild-type Syrian hamsters, human ACE2 (hACE2) transgenic hamsters, and hACE2 transgenic mice. we observed no obvious differences among BA.2, BA.4, and BA.5 isolates in growth ability or pathogenicity in rodent models, and less pathogenicity compared to a previously circulating Delta (B.1.617.2 lineage) isolate. In addition, in vivo competition experiments revealed that BA.5 outcompeted BA.2 in hamsters, whereas BA.4 and BA.2 exhibited similar fitness. These findings suggest that BA.4 and BA.5 clinical isolates have similar pathogenicity to BA.2 in rodents and that BA.5 possesses viral fitness superior to that of BA.2.

3.
Nat Commun ; 13(1): 6100, 2022 Oct 15.
Article in English | MEDLINE | ID: covidwho-2077054

ABSTRACT

In cultured cells, SARS-CoV-2 infects cells via multiple pathways using different host proteases. Recent studies have shown that the furin and TMPRSS2 (furin/TMPRSS2)-dependent pathway plays a minor role in infection of the Omicron variant. Here, we confirm that Omicron uses the furin/TMPRSS2-dependent pathway inefficiently and enters cells mainly using the cathepsin-dependent endocytosis pathway in TMPRSS2-expressing VeroE6/TMPRSS2 and Calu-3 cells. This is the case despite efficient cleavage of the spike protein of Omicron. However, in the airways of TMPRSS2-knockout mice, Omicron infection is significantly reduced. We furthermore show that propagation of the mouse-adapted SARS-CoV-2 QHmusX strain and human clinical isolates of Beta and Gamma is reduced in TMPRSS2-knockout mice. Therefore, the Omicron variant isn't an exception in using TMPRSS2 in vivo, and analysis with TMPRSS2-knockout mice is important when evaluating SARS-CoV-2 variants. In conclusion, this study shows that TMPRSS2 is critically important for SARS-CoV-2 infection of murine airways, including the Omicron variant.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , Humans , Mice , Cathepsins , Furin/genetics , Furin/metabolism , Mice, Knockout , Peptide Hydrolases , Serine Endopeptidases/genetics , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Virus Internalization
6.
Med (N Y) ; 3(6): 406-421.e4, 2022 Jun 10.
Article in English | MEDLINE | ID: covidwho-1926779

ABSTRACT

BACKGROUND: The Omicron variant of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) was identified in Japan in November 2021. This variant contains up to 36 mutations in the spike protein, the target of neutralizing antibodies, and can escape vaccine-induced immunity. A booster vaccination campaign began with healthcare workers and high-risk groups. The safety and immunogenicity of the three-dose vaccination against Omicron remain unknown. METHODS: A total of 272 healthcare workers were initially evaluated for long-term vaccine safety and immunogenicity. We further established a vaccinee panel to evaluate the safety and immunogenicity against variants of concern (VOCs), including the Omicron variants, using a live virus microneutralization assay. FINDINGS: Two-dose vaccination induced robust anti-spike antibodies and neutralization titers (NTs) against the ancestral strain WK-521, whereas NTs against VOCs were significantly lower. Within 93-247 days of the second vaccine dose, NTs against Omicron were completely abolished in up to 80% of individuals in the vaccinee panel. Booster dose induced a robust increase in anti-spike antibodies and NTs against the WK-521, Delta, and Omicron variants. There were no significant differences in the neutralization ability of sera from boosted individuals among the Omicron subvariants BA.1, BA.1.1, and BA.2. Boosting increased the breadth of humoral immunity and cross-reactivity with Omicron without changes in cytokine signatures and adverse event rate. CONCLUSIONS: The third vaccination dose is safe and increases neutralization against Omicron variants. FUNDING: This study was supported by grants from AMED (grants JP21fk0108104 and JP21mk0102146).


Subject(s)
Antibodies, Viral , BNT162 Vaccine , COVID-19 , Immunization, Secondary , Immunogenicity, Vaccine , Antibodies, Neutralizing , BNT162 Vaccine/immunology , COVID-19/prevention & control , Cross Reactions , Humans , Immunity, Humoral , Neutralization Tests , RNA, Messenger , SARS-CoV-2/genetics
7.
Antiviral Res ; 205: 105372, 2022 09.
Article in English | MEDLINE | ID: covidwho-1914151

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron subvariant BA.2 has spread in many countries, replacing the earlier Omicron subvariant BA.1 and other variants. Here, using a cell culture infection assay, we quantified the intrinsic sensitivity of BA.2 and BA.1 compared with other variants of concern, Alpha, Gamma, and Delta, to five approved-neutralizing antibodies and antiviral drugs. Our assay revealed the diverse sensitivities of these variants to antibodies, including the loss of response of both BA.1 and BA.2 to casirivimab and of BA.1 to imdevimab. In contrast, EIDD-1931 and nirmatrelvir showed a more conserved activities to these variants. The viral response profile combined with mathematical analysis estimated differences in antiviral effects among variants in the clinical concentrations. These analyses provide essential evidence that gives insight into variant emergence's impact on choosing optimal drug treatment.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Monoclonal, Humanized , Antibodies, Neutralizing , Antibodies, Viral , Antiviral Agents/pharmacology , COVID-19/drug therapy , Humans
8.
PLoS Pathog ; 18(6): e1010590, 2022 06.
Article in English | MEDLINE | ID: covidwho-1892333

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been transmitted across all over the world, in contrast to the limited epidemic of genetically- and virologically-related SARS-CoV. However, the molecular basis explaining the difference in the virological characteristics among SARS-CoV-2 and SARS-CoV has been poorly defined. Here we identified that host sialoglycans play a significant role in the efficient spread of SARS-CoV-2 infection, while this was not the case with SARS-CoV. SARS-CoV-2 infection was significantly inhibited by α2-6-linked sialic acid-containing compounds, but not by α2-3 analog, in VeroE6/TMPRSS2 cells. The α2-6-linked compound bound to SARS-CoV-2 spike S1 subunit to competitively inhibit SARS-CoV-2 attachment to cells. Enzymatic removal of cell surface sialic acids impaired the interaction between SARS-CoV-2 spike and angiotensin-converting enzyme 2 (ACE2), and suppressed the efficient spread of SARS-CoV-2 infection over time, in contrast to its least effect on SARS-CoV spread. Our study provides a novel molecular basis of SARS-CoV-2 infection which illustrates the distinctive characteristics from SARS-CoV.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Peptidyl-Dipeptidase A/metabolism , Polysaccharides/metabolism , Protein Binding , Spike Glycoprotein, Coronavirus/metabolism
9.
Med (N Y) ; 3(4): 249-261.e4, 2022 04 08.
Article in English | MEDLINE | ID: covidwho-1783638

ABSTRACT

Background: The immune profile against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has dramatically diversified due to a complex combination of exposure to vaccines and infection by various lineages/variants, likely generating a heterogeneity in protective immunity in a given population. To further complicate this, the Omicron variant, with numerous spike mutations, has emerged. These circumstances have created the need to assess the potential of immune evasion by Omicron in individuals with various immune histories. Methods: The neutralization susceptibility of the variants, including Omicron and their ancestors, was comparably assessed using a panel of plasma/serum derived from individuals with divergent immune histories. Blood samples were collected from either mRNA vaccinees or from those who suffered from breakthrough infections of Alpha/Delta with multiple time intervals following vaccination. Findings: Omicron was highly resistant to neutralization in fully vaccinated individuals without a history of breakthrough infections. In contrast, robust cross-neutralization against Omicron was induced in vaccinees that experienced breakthrough infections. The time interval between vaccination and infection, rather than the variant types of infection, was significantly correlated with the magnitude and potency of Omicron-neutralizing antibodies. Conclusions: Immune histories with breakthrough infections can overcome the resistance to infection by Omicron, with the vaccination-infection interval being the key determinant of the magnitude and breadth of neutralization. The diverse exposure history in each individual warrants a tailored and cautious approach to understanding population immunity against Omicron and future variants. Funding: This study was supported by grants from the Japan Agency for Medical Research and Development (AMED).


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , COVID-19 Vaccines , Humans , Postoperative Complications , Vaccination
10.
Sci Immunol ; 7(70): eabn8590, 2022 04 22.
Article in English | MEDLINE | ID: covidwho-1673342

ABSTRACT

Multiple SARS-CoV-2 variants have mutations in the spike receptor binding domain (RBD) with potential to evade neutralizing antibody. In particular, the Beta and Omicron variants escape from antibody neutralizing activity in those who received two doses of BNT162b2 mRNA vaccine. Nonetheless, boosting with a third vaccine dose or by breakthrough infection improves the overall breadth of the neutralizing antibodies, but the mechanism remains unclear. Here, we longitudinally profiled the cellular composition of RBD-binding memory B cell subsets and their antibody binding and neutralizing activity against SARS-CoV-2 variants after the second dose of mRNA vaccine. Two doses of the mRNA vaccine elicited plasma neutralizing antibodies with a limited activity against Beta and Omicron but induced an expanded antibody breadth overtime, up to 4.9 months after vaccination. In contrast, more than one-third of RBD-binding IgG+ memory B cells with a resting phenotype initially bound the Beta and Omicron variants and steadily increased the B cell receptor breadth overtime. As a result, a fraction of the resting memory B cell subset secreted Beta and Omicron-neutralizing antibody when stimulated in vitro. The neutralizing breadth of the resting memory B cell subset helps us understand the prominent recall of Omicron-neutralizing antibodies after an additional booster or breakthrough infection in fully vaccinated individuals.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines , Humans , Vaccines, Synthetic
11.
Jpn J Infect Dis ; 74(5): 465-472, 2021 Sep 22.
Article in English | MEDLINE | ID: covidwho-1436361

ABSTRACT

Soon after the 2019 outbreak of coronavirus disease 2019 in Wuhan, China, a protocol for real-time RT-PCR assay detection of severe acute respiratory syndrome coronavirus (SARS-CoV-2) was established by the National Institute of Infectious Diseases (NIID) in Japan. The protocol used Charité's nucleocapsid (Sarbeco-N) and NIID nucleocapsid (NIID-N2) assays. During the following months, SARS-CoV-2 spread and caused a global pandemic, and various SARS-CoV-2 sequences were registered in public databases, such as the Global Initiative on Sharing All Influenza Data (GISAID). In this study, we evaluated the S2 assay (NIID-S2) that was newly developed to replace the Sarbeco-N assay and the performance of the NIID-N2 and NIID-S2 assays, referring to mismatches in the primer/probe targeted region. We found that the analytical sensitivity and specificity of the NIID-S2 set were comparable to those of the NIID-N2 assay, and the detection rate for clinical specimens was identical to that of the NIID-N2 assay. Furthermore, among the available sequences (approximately 192,000), the NIID-N2 and NIID-S2 sets had 2.6% and 1.2% mismatched sequences, respectively, although most of these mismatches did not affect the amplification efficiency, except the 3' end of the NIID-N2 forward primer. These findings indicate that the previously developed NIID-N2 assay is suitable for the detection of SARS-CoV-2 with support from the newly developed NIID-S2 set.


Subject(s)
COVID-19 Nucleic Acid Testing/methods , COVID-19/diagnosis , SARS-CoV-2/isolation & purification , Coronavirus Nucleocapsid Proteins/genetics , DNA Primers/genetics , Humans , Japan , Phosphoproteins/genetics , RNA, Viral/analysis , RNA, Viral/genetics , SARS-CoV-2/genetics , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus/genetics
12.
Immunity ; 54(10): 2385-2398.e10, 2021 10 12.
Article in English | MEDLINE | ID: covidwho-1370548

ABSTRACT

Potent neutralizing SARS-CoV-2 antibodies often target the spike protein receptor-binding site (RBS), but the variability of RBS epitopes hampers broad neutralization of multiple sarbecoviruses and drifted viruses. Here, using humanized mice, we identified an RBS antibody with a germline VH gene that potently neutralized SARS-related coronaviruses, including SARS-CoV and SARS-CoV-2 variants. X-ray crystallography revealed coordinated recognition by the heavy chain of non-RBS conserved sites and the light chain of RBS with a binding angle mimicking the angiotensin-converting enzyme 2 (ACE2) receptor. The minimum footprints in the hypervariable region of RBS contributed to the breadth of neutralization, which was enhanced by immunoglobulin G3 (IgG3) class switching. The coordinated binding resulted in broad neutralization of SARS-CoV and emerging SARS-CoV-2 variants of concern. Low-dose therapeutic antibody treatment in hamsters reduced the virus titers and morbidity during SARS-CoV-2 challenge. The structural basis for broad neutralizing activity may inform the design of a broad spectrum of therapeutics and vaccines.


Subject(s)
Broadly Neutralizing Antibodies/immunology , Cross Reactions/immunology , SARS-CoV-2/immunology , Animals , Betacoronavirus/immunology , Binding Sites, Antibody , Broadly Neutralizing Antibodies/chemistry , Broadly Neutralizing Antibodies/therapeutic use , COVID-19/prevention & control , COVID-19/therapy , COVID-19/virology , Cricetinae , Humans , Immunoglobulin Class Switching , Immunoglobulin Fab Fragments/chemistry , Immunoglobulin Fab Fragments/metabolism , Immunoglobulin G/chemistry , Immunoglobulin G/immunology , Mice , Protein Domains , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , Spike Glycoprotein, Coronavirus/metabolism
13.
PLoS Negl Trop Dis ; 15(7): e0009553, 2021 07.
Article in English | MEDLINE | ID: covidwho-1360646

ABSTRACT

BACKGROUND: Jamestown Canyon virus (JCV) is a mosquito-borne orthobunyavirus that causes acute febrile illness, meningitis, and meningoencephalitis, primarily in North American adults. Currently, there are no available vaccines or specific treatments against JCV infections. METHODOLOGY/PRINCIPAL FINDINGS: The antiviral efficacy of favipiravir (FPV) against JCV infection was evaluated in vitro and in vivo in comparison with that of ribavirin (RBV) and 2'-fluoro-2'-deoxycytidine (2'-FdC). The in vitro inhibitory effect of these drugs on JCV replication was evaluated in Vero and Neuro-2a (N2A) cells. The efficacy of FPV in the treatment of JCV infection in vivo was evaluated in C57BL/6J mice inoculated intracerebrally with JCV, as per the survival, viral titers in the brain, and viral RNA load in the blood. The 90% inhibitory concentrations (IC90) of FPV, RBV, and 2'-FdC were 41.0, 61.8, and 13.6 µM in Vero cells and 20.7, 25.8, and 8.8 µM in N2A cells, respectively. All mice infected with 1.0×104 TCID50 died or were sacrificed within 10 days post-infection (dpi) without treatment. However, mice treated with FPV for 5 days [initiated either 2 days prior to infection (-2 dpi-2 dpi) or on the day of infection (0 dpi-4 dpi)] survived significantly longer than control mice, administered with PBS (p = 0.025 and 0.011, respectively). Moreover, at 1 and 3 dpi, the virus titers in the brain were significantly lower in FPV-treated mice (0 dpi-4 dpi) versus PBS-treated mice (p = 0.002 for both 1 and 3 dpi). CONCLUSIONS/SIGNIFICANCE: Although the intracerebral inoculation route is thought to be a challenging way to evaluate drug efficacy, FPV inhibits the in vitro replication of JCV and prolongs the survival of mice intracerebrally inoculated with JCV. These results will enable the development of a specific antiviral treatment against JCV infections and establishment of an effective animal model.


Subject(s)
Amides/administration & dosage , Antiviral Agents/administration & dosage , Encephalitis Virus, California/drug effects , Encephalitis, California/drug therapy , Pyrazines/administration & dosage , Animals , Chlorocebus aethiops , Disease Models, Animal , Drug Evaluation, Preclinical , Encephalitis Virus, California/genetics , Encephalitis Virus, California/growth & development , Encephalitis, California/mortality , Encephalitis, California/virology , Female , Humans , Mice , Mice, Inbred C57BL , Vero Cells
14.
Immunity ; 54(8): 1841-1852.e4, 2021 08 10.
Article in English | MEDLINE | ID: covidwho-1293863

ABSTRACT

Antibody titers against SARS-CoV-2 slowly wane over time. Here, we examined how time affects antibody potency. To assess the impact of antibody maturation on durable neutralizing activity against original SARS-CoV-2 and emerging variants of concern (VOCs), we analyzed receptor binding domain (RBD)-specific IgG antibodies in convalescent plasma taken 1-10 months after SARS-CoV-2 infection. Longitudinal evaluation of total RBD IgG and neutralizing antibody revealed declining total antibody titers but improved neutralization potency per antibody to original SARS-CoV-2, indicative of antibody response maturation. Neutralization assays with authentic viruses revealed that early antibodies capable of neutralizing original SARS-CoV-2 had limited reactivity toward B.1.351 (501Y.V2) and P.1 (501Y.V3) variants. Antibodies from late convalescents exhibited increased neutralization potency to VOCs, suggesting persistence of cross-neutralizing antibodies in plasma. Thus, maturation of the antibody response to SARS-CoV-2 potentiates cross-neutralizing ability to circulating variants, suggesting that declining antibody titers may not be indicative of declining protection.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , COVID-19/virology , SARS-CoV-2/immunology , Antibodies, Monoclonal/immunology , Antibody Specificity , COVID-19/epidemiology , Humans , Immunoglobulin G , Neutralization Tests , SARS-CoV-2/genetics , Viral Load
15.
Proc Natl Acad Sci U S A ; 118(27)2021 07 06.
Article in English | MEDLINE | ID: covidwho-1276013

ABSTRACT

The spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) plays a key role in viral infectivity. It is also the major antigen stimulating the host's protective immune response, specifically, the production of neutralizing antibodies. Recently, a new variant of SARS-CoV-2 possessing multiple mutations in the S protein, designated P.1, emerged in Brazil. Here, we characterized a P.1 variant isolated in Japan by using Syrian hamsters, a well-established small animal model for the study of SARS-CoV-2 disease (COVID-19). In hamsters, the variant showed replicative abilities and pathogenicity similar to those of early and contemporary strains (i.e., SARS-CoV-2 bearing aspartic acid [D] or glycine [G] at position 614 of the S protein). Sera and/or plasma from convalescent patients and BNT162b2 messenger RNA vaccinees showed comparable neutralization titers across the P.1 variant, S-614D, and S-614G strains. In contrast, the S-614D and S-614G strains were less well recognized than the P.1 variant by serum from a P.1-infected patient. Prior infection with S-614D or S-614G strains efficiently prevented the replication of the P.1 variant in the lower respiratory tract of hamsters upon reinfection. In addition, passive transfer of neutralizing antibodies to hamsters infected with the P.1 variant or the S-614G strain led to reduced virus replication in the lower respiratory tract. However, the effect was less pronounced against the P.1 variant than the S-614G strain. These findings suggest that the P.1 variant may be somewhat antigenically different from the early and contemporary strains of SARS-CoV-2.


Subject(s)
COVID-19/virology , SARS-CoV-2/physiology , SARS-CoV-2/pathogenicity , Virus Replication , Animals , Antibodies, Neutralizing , COVID-19/diagnostic imaging , COVID-19/pathology , Cricetinae , Humans , Immunogenicity, Vaccine , Lung/pathology , Mesocricetus , Mice , Spike Glycoprotein, Coronavirus/genetics , X-Ray Microtomography
16.
Microbiol Immunol ; 64(1): 33-51, 2020 Jan.
Article in English | MEDLINE | ID: covidwho-1262996

ABSTRACT

The spike (S) protein of coronavirus, which binds to cellular receptors and mediates membrane fusion for cell entry, is a candidate vaccine target for blocking coronavirus infection. However, some animal studies have suggested that inadequate immunization against severe acute respiratory syndrome coronavirus (SARS-CoV) induces a lung eosinophilic immunopathology upon infection. The present study evaluated two kinds of vaccine adjuvants for use with recombinant S protein: gold nanoparticles (AuNPs), which are expected to function as both an antigen carrier and an adjuvant in immunization; and Toll-like receptor (TLR) agonists, which have previously been shown to be an effective adjuvant in an ultraviolet-inactivated SARS-CoV vaccine. All the mice immunized with more than 0.5 µg S protein without adjuvant escaped from SARS after infection with mouse-adapted SARS-CoV; however, eosinophilic infiltrations were observed in the lungs of almost all the immunized mice. The AuNP-adjuvanted protein induced a strong IgG response but failed to improve vaccine efficacy or to reduce eosinophilic infiltration because of highly allergic inflammatory responses. Whereas similar virus titers were observed in the control animals and the animals immunized with S protein with or without AuNPs, Type 1 interferon and pro-inflammatory responses were moderate in the mice treated with S protein with and without AuNPs. On the other hand, the TLR agonist-adjuvanted vaccine induced highly protective antibodies without eosinophilic infiltrations, as well as Th1/17 cytokine responses. The findings of this study will support the development of vaccines against severe pneumonia-associated coronaviruses.


Subject(s)
Adjuvants, Immunologic/pharmacology , Coronavirus Infections/prevention & control , Gold/chemistry , Immunoglobulin G/immunology , Lung/immunology , Metal Nanoparticles/chemistry , Severe Acute Respiratory Syndrome/prevention & control , Spike Glycoprotein, Coronavirus/immunology , Analysis of Variance , Animals , Antibodies, Viral/immunology , Chlorocebus aethiops , Coronavirus/immunology , Coronavirus Infections/immunology , Coronavirus Infections/virology , Cytokines/metabolism , Disease Models, Animal , Female , Immunization , Lung/pathology , Mice , Mice, Inbred BALB C , Recombinant Proteins/immunology , Severe Acute Respiratory Syndrome/immunology , Severe Acute Respiratory Syndrome/virology , Spike Glycoprotein, Coronavirus/genetics , Toll-Like Receptors , Vaccination , Vaccines, Synthetic , Vero Cells , Viral Envelope Proteins/genetics , Viral Envelope Proteins/immunology , Viral Vaccines/immunology , Viral Vaccines/pharmacology , Viral Vaccines/therapeutic use
17.
Front Microbiol ; 12: 651403, 2021.
Article in English | MEDLINE | ID: covidwho-1231355

ABSTRACT

Coronavirus disease 2019 (COVID-19) has caused serious public health, social, and economic damage worldwide and effective drugs that prevent or cure COVID-19 are urgently needed. Approved drugs including Hydroxychloroquine, Remdesivir or Interferon were reported to inhibit the infection or propagation of severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2), however, their clinical efficacies have not yet been well demonstrated. To identify drugs with higher antiviral potency, we screened approved anti-parasitic/anti-protozoal drugs and identified an anti-malarial drug, Mefloquine, which showed the highest anti-SARS-CoV-2 activity among the tested compounds. Mefloquine showed higher anti-SARS-CoV-2 activity than Hydroxychloroquine in VeroE6/TMPRSS2 and Calu-3 cells, with IC50 = 1.28 µM, IC90 = 2.31 µM, and IC99 = 4.39 µM in VeroE6/TMPRSS2 cells. Mefloquine inhibited viral entry after viral attachment to the target cell. Combined treatment with Mefloquine and Nelfinavir, a replication inhibitor, showed synergistic antiviral activity. Our mathematical modeling based on the drug concentration in the lung predicted that Mefloquine administration at a standard treatment dosage could decline viral dynamics in patients, reduce cumulative viral load to 7% and shorten the time until virus elimination by 6.1 days. These data cumulatively underscore Mefloquine as an anti-SARS-CoV-2 entry inhibitor.

18.
BMJ Open Respir Res ; 8(1)2021 02.
Article in English | MEDLINE | ID: covidwho-1102195

ABSTRACT

BACKGROUND: An outbreak of novel coronavirus (SARS-CoV-2)-associated respiratory infectious diseases (COVID-19) emerged in 2019 and has spread rapidly in humans around the world. The demonstration of in vitro infectiousness of respiratory specimens is an informative surrogate for SARS-CoV-2 transmission from patients with COVID-19; accordingly, viral isolation assays in cell culture are an important aspect of laboratory diagnostics for COVID-19. METHODS: We developed a simple and rapid protocol for isolating SARS-CoV-2 from respiratory specimens using VeroE6/TMPRSS2 cells, a cell line that is highly susceptible to the virus. We also investigated a correlation between isolation of SARS-CoV-2 and viral load detected by real-time RT-PCR (rRT-PCR) using N2 primer/probe set that has been developed for testing of COVID-19 in Japan. RESULTS: The SARS-CoV-2 isolation protocol did not require blind passage of inoculated cells and yielded the results of viral isolation within 7 days after inoculation. Specimens with cycle threshold (Ct) values of <20.2, determined by rRT-PCR, were predicted to be isolation-positive. On the other hand, 6.9% of specimens with Ct values >35 were virus isolation-positive, indicating that low viral loads (high Ct values) in upper respiratory specimens do not always indicate no risk of containing transmissible virus. CONCLUSION: In combination with rRT-PCR, the SARS-CoV-2 isolation protocol provides a means for assessing the potential risk of transmissible virus in upper respiratory specimens.


Subject(s)
COVID-19/transmission , SARS-CoV-2/pathogenicity , Animals , COVID-19 Nucleic Acid Testing , Cell Line , Chlorocebus aethiops , Cytopathogenic Effect, Viral , Humans , Nasal Cavity/virology , Nasopharynx/virology , SARS-CoV-2/isolation & purification , Saliva/virology , Serine Endopeptidases/genetics , Specimen Handling , Vero Cells
19.
Virol J ; 18(1): 16, 2021 01 12.
Article in English | MEDLINE | ID: covidwho-1059645

ABSTRACT

BACKGROUND: SARS-CoV-2 is a novel coronavirus that emerged in 2019 and is now classified in the genus Coronavirus with closely related SARS-CoV. SARS-CoV-2 is highly pathogenic in humans and is classified as a biosafety level (BSL)-3 pathogen, which makes manipulating it relatively difficult due to its infectious nature. METHODS: To circumvent the need for BSL-3 laboratories, an alternative assay was developed that avoids live virus and instead uses a recombinant VSV expressing luciferase and possesses the full length or truncated spike proteins of SARS-CoV-2. Furthermore, to measure SARS-CoV-2 neutralizing antibodies under BSL2 conditions, a chemiluminescence reduction neutralization test (CRNT) for SARS-CoV-2 was developed. The neutralization values of the serum samples collected from hospitalized patients with COVID-19 or SARS-CoV-2 PCR-negative donors against the pseudotyped virus infection evaluated by the CRNT were compared with antibody titers determined from an enzyme-linked immunosorbent assay (ELISA) or an immunofluorescence assay (IFA). RESULTS: The CRNT, which used whole blood collected from hospitalized patients with COVID-19, was also examined. As a result, the inhibition of pseudotyped virus infection was specifically observed in both serum and whole blood and was also correlated with the results of the IFA. CONCLUSIONS: In conclusion, the CRNT for COVID-19 is a convenient assay system that can be performed in a BSL-2 laboratory with high specificity and sensitivity for evaluating the occurrence of neutralizing antibodies against SARS-CoV-2.


Subject(s)
Antibodies, Neutralizing/blood , COVID-19 Serological Testing/methods , COVID-19/blood , Neutralization Tests/methods , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Vesicular stomatitis Indiana virus/genetics , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/immunology , Cell Line , Convalescence , Humans , Inhibitory Concentration 50 , Luminescence , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
20.
J Virol ; 95(1)2020 12 09.
Article in English | MEDLINE | ID: covidwho-968111

ABSTRACT

Here, we screened steroid compounds to obtain a drug expected to block host inflammatory responses and Middle East respiratory syndrome coronavirus (MERS-CoV) replication. Ciclesonide, an inhaled corticosteroid, suppressed the replication of MERS-CoV and other coronaviruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), in cultured cells. The 90% effective concentration (EC90) of ciclesonide for SARS-CoV-2 in differentiated human bronchial tracheal epithelial cells was 0.55 µM. Eight consecutive passages of 43 SARS-CoV-2 isolates in the presence of ciclesonide generated 15 resistant mutants harboring single amino acid substitutions in nonstructural protein 3 (nsp3) or nsp4. Of note, ciclesonide suppressed the replication of all these mutants by 90% or more, suggesting that these mutants cannot completely overcome ciclesonide blockade. Under a microscope, the viral RNA replication-transcription complex in cells, which is thought to be detectable using antibodies specific for nsp3 and double-stranded RNA, was observed to fall in the presence of ciclesonide in a concentration-dependent manner. These observations indicate that the suppressive effect of ciclesonide on viral replication is specific to coronaviruses, highlighting it as a candidate drug for the treatment of COVID-19 patients.IMPORTANCE The outbreak of SARS-CoV-2, the cause of COVID-19, is ongoing. New and effective antiviral agents that combat the disease are needed urgently. Here, we found that an inhaled corticosteroid, ciclesonide, suppresses the replication of coronaviruses, including betacoronaviruses (murine hepatitis virus type 2 [MHV-2], MERS-CoV, SARS-CoV, and SARS-CoV-2) and an alphacoronavirus (human coronavirus 229E [HCoV-229E]), in cultured cells. Ciclesonide is safe; indeed, it can be administered to infants at high concentrations. Thus, ciclesonide is expected to be a broad-spectrum antiviral drug that is effective against many members of the coronavirus family. It could be prescribed for the treatment of MERS and COVID-19.


Subject(s)
COVID-19/metabolism , Pregnenediones/pharmacology , RNA, Double-Stranded/biosynthesis , RNA, Viral/biosynthesis , SARS-CoV-2/physiology , Virus Replication/drug effects , Animals , Chlorocebus aethiops , Dogs , HeLa Cells , Humans , Madin Darby Canine Kidney Cells , Vero Cells
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