scholarly journals Characterization of a new SARS-CoV-2 variant that emerged in Brazil

2021 ◽  
Vol 118 (27) ◽  
pp. e2106535118
Author(s):  
Masaki Imai ◽  
Peter J. Halfmann ◽  
Seiya Yamayoshi ◽  
Kiyoko Iwatsuki-Horimoto ◽  
Shiho Chiba ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Messenger Rna ◽  
Neutralizing Antibodies ◽  
Lower Respiratory Tract ◽  
Small Animal ◽  
S Protein ◽  
New Variant ◽  
Major Antigen ◽  
Prior Infection

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.

scholarly journals SARS-CoV-2 mRNA vaccines induce a robust germinal centre reaction in humans

2021 ◽  
Author(s):  
Ali Ellebedy ◽  
Jackson Turner ◽  
Jane O'Halloran ◽  
Elizaveta Kalaidina ◽  
Wooseob Kim ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Messenger Rna ◽  
Neutralizing Antibodies ◽  
Germinal Centre ◽  
S Protein ◽  
Fine Needle Aspirates ◽  
Cell Responses ◽  
Cell Clones ◽  
Shared Epitopes

Abstract Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) messenger RNA (mRNA)-based vaccines are ~95% effective in preventing coronavirus disease 2019. However, the dynamics of antibody secreting plasmablasts (PBs) and germinal centre (GC) B cells induced by these vaccines in SARS-CoV-2 naïve and antigen-experienced humans remains unclear. Here we examined peripheral blood and/or lymph node (LN) antigen-specific B cell responses in 32 individuals who received two doses of BNT162b2, an mRNA-based vaccine encoding the full-length SARS-CoV-2 spike (S) gene. Circulating IgG- and IgA-secreting PBs targeting the S protein peaked one week after the second immunization then declined and were undetectable three weeks later. PB responses coincided with maximal levels of serum anti-S binding and neutralizing antibodies to a historical strain as well as emerging variants, especially in individuals previously infected with SARS-CoV-2, who produced the most robust serological responses. Fine needle aspirates of draining axillary LNs identified GC B cells that bind S protein in all participants sampled after primary immunization. GC responses increased after boosting and were detectable in two distinct LNs in several participants. Remarkably, high frequencies of S-binding GC B cells and PBs were maintained in draining LNs for up to seven weeks after first immunization, with a substantial fraction of the PB pool class-switched to IgA. GC B cell-derived monoclonal antibodies predominantly targeted the RBD, with fewer clones binding to the N-terminal domain or shared epitopes within the S proteins of human betacoronaviruses OC43 and HKU1. Our studies demonstrate that SARS-CoV-2 mRNA-based vaccination of humans induces a robust and persistent GC B cell response that engages pre-existing as well as new B cell clones, which enables generation of high-affinity, broad, and durable humoral immunity.

scholarly journals Immunogenicity of low dose prime-boost vaccination of mRNA vaccine CV07050101 in non-human primates

2021 ◽  
Author(s):  
Neeltje van Doremalen ◽  
Robert Fischer ◽  
Jonathan Schulz ◽  
Myndi Holbrook ◽  
Brian Smith ◽  
...  
Keyword(s):  
Immune Responses ◽  
Neutralizing Antibodies ◽  
Vaccine Candidate ◽  
Small Animal ◽  
S Protein ◽  
Cell Responses ◽  
Cellular Immune Responses ◽  
Boost Vaccination ◽  
Human Volunteers ◽  
Cellular Immune

Many different vaccine candidates against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the etiological agent of COVID-19, are currently approved and under development. Vaccine platforms vary from mRNA vaccines to viral-vectored vaccines, and several candidates have been shown to produce humoral and cellular responses in small animal models, non-human primates and human volunteers. In this study, six non-human primates received a prime-boost intramuscular vaccination with 4 μg of mRNA vaccine candidate CV07050101, which encodes a pre-fusion stabilized spike (S) protein of SARS-CoV-2. Boost vaccination was performed 28 days post prime vaccination. As a control, six animals were similarly injected with PBS. Humoral and cellular immune responses were investigated at time of vaccination, and two weeks afterwards. No antibodies could be detected two and four weeks after prime vaccination. Two weeks after boost vaccination, binding but no neutralizing antibodies were detected in 4 out of 6 non-human primates. SARS-CoV-2 S protein specific T cell responses were detected in these 4 animals. In conclusion, prime-boost vaccination with 4 μg of vaccine candidate CV07050101 resulted in limited immune responses in 4 out of 6 non-human primates.

scholarly journals Phase 2b Study of an Ad26.RSV.preF Vaccine for Prevention of RSV-mediated Respiratory Tract Disease in Older Adults

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. 1050-1051
Author(s):  
Ann Falsey ◽  
Kristi Williams ◽  
Efi Gymnopoulou ◽  
Stephan Bart ◽  
John Ervin ◽  
...  
Keyword(s):  
Older Adults ◽  
Respiratory Tract ◽  
Neutralizing Antibodies ◽  
Lower Respiratory Tract ◽  
Specific Binding ◽  
Geometric Mean ◽  
Median Frequency ◽  
Respiratory Tract Disease ◽  
Double Blind ◽  
Tract Disease

Abstract Respiratory syncytial virus (RSV) may cause serious lower respiratory tract disease (LRTD) in older adults, and there is currently no licensed vaccine. CYPRESS (NCT03982199) is a randomized, double-blind, placebo-controlled Phase 2b proof-of-concept trial of an Ad26.RSV.preF-based vaccine for the prevention of RSV-mediated LRTD in older adults. Adults aged ≥65 years were randomized 1:1 before the RSV season to receive Ad26.RSV.preF-based vaccine or placebo. Acute respiratory infection symptoms were collected through a patient eDiary and/or clinician assessment until the end of the RSV season. The primary endpoint was the first occurrence of RTPCR-confirmed RSV-mediated LRTD according to any of 3 case definitions: (1) ≥3 symptoms of lower respiratory tract infection (LRTI), (2) ≥2 symptoms of LRTI, or (3) ≥2 symptoms of LRTI or ≥1 symptom of LRTI with ≥1 systemic symptom. Immunogenicity was assessed in a subset of approximately 200 participants. A total of 2891 participants in each study arm received study treatment. Vaccine efficacy was 80% (94.2% CI, 52.2-92.9%), 75% (50.1-88.5%), and 69.8% (43.7-84.7%) for case definition 1, 2, and 3, respectively (all P <0.001). In the vaccine arm, geometric mean fold increase in antibody titers 14 days after vaccination was 13.5 for RSV neutralizing antibodies and 8.6 for RSV prefusion F-specific binding antibodies, and median frequency of RSV-F-specific INFγ T-cells increased from 34 to 444 SFC/10^6 PBMC; no relevant changes were observed in the placebo arm. The Ad26.RSV.preF-based vaccine was highly effective against RSV-mediated LRTD through the first RSV season and elicited robust immune responses in older adults.

scholarly journals K18-hACE2 mice develop respiratory disease resembling severe COVID-19

2021 ◽  
Vol 17 (1) ◽  
pp. e1009195 ◽  
Author(s):  
Claude Kwe Yinda ◽  
Julia R. Port ◽  
Trenton Bushmaker ◽  
Irene Offei Owusu ◽  
Jyothi N. Purushotham ◽  
...  
Keyword(s):  
Animal Models ◽  
Respiratory Tract ◽  
Lower Respiratory Tract ◽  
Small Animal ◽  
Future Application ◽  
Rapid Weight Loss ◽  
Disease Course ◽  
Mild Disease ◽  
Disease Spectrum ◽  
Moderate Disease

SARS-CoV-2 emerged in late 2019 and resulted in the ongoing COVID-19 pandemic. Several animal models have been rapidly developed that recapitulate the asymptomatic to moderate disease spectrum. Now, there is a direct need for additional small animal models to study the pathogenesis of severe COVID-19 and for fast-tracked medical countermeasure development. Here, we show that transgenic mice expressing the human SARS-CoV-2 receptor (angiotensin-converting enzyme 2 [hACE2]) under a cytokeratin 18 promoter (K18) are susceptible to SARS-CoV-2 and that infection resulted in a dose-dependent lethal disease course. After inoculation with either 104 TCID50 or 105 TCID50, the SARS-CoV-2 infection resulted in rapid weight loss in both groups and uniform lethality in the 105 TCID50 group. High levels of viral RNA shedding were observed from the upper and lower respiratory tract and intermittent shedding was observed from the intestinal tract. Inoculation with SARS-CoV-2 resulted in upper and lower respiratory tract infection with high infectious virus titers in nasal turbinates, trachea and lungs. The observed interstitial pneumonia and pulmonary pathology, with SARS-CoV-2 replication evident in pneumocytes, were similar to that reported in severe cases of COVID-19. SARS-CoV-2 infection resulted in macrophage and lymphocyte infiltration in the lungs and upregulation of Th1 and proinflammatory cytokines/chemokines. Extrapulmonary replication of SARS-CoV-2 was observed in the cerebral cortex and hippocampus of several animals at 7 DPI but not at 3 DPI. The rapid inflammatory response and observed pathology bears resemblance to COVID-19. Additionally, we demonstrate that a mild disease course can be simulated by low dose infection with 102 TCID50 SARS-CoV-2, resulting in minimal clinical manifestation and near uniform survival. Taken together, these data support future application of this model to studies of pathogenesis and medical countermeasure development.

scholarly journals Severe Acute Respiratory Syndrome Coronavirus Infection of Golden Syrian Hamsters

2005 ◽  
Vol 79 (1) ◽  
pp. 503-511 ◽  
Author(s):  
Anjeanette Roberts ◽  
Leatrice Vogel ◽  
Jeannette Guarner ◽  
Norman Hayes ◽  
Brian Murphy ◽  
...  
Keyword(s):  
Severe Acute Respiratory Syndrome ◽  
Respiratory Tract ◽  
Virus Replication ◽  
Neutralizing Antibodies ◽  
Antiviral Agents ◽  
Small Animal ◽  
Pulmonary Tissue ◽  
Syrian Hamsters ◽  
Significant Pathology ◽  
Coronavirus Infection

ABSTRACT Small animal models are needed in order to evaluate the efficacy of candidate vaccines and antivirals directed against the severe acute respiratory syndrome coronavirus (SARS CoV). We investigated the ability of SARS CoV to infect 5-week-old Golden Syrian hamsters. When administered intranasally, SARS CoV replicates to high titers in the lungs and nasal turbinates. Peak replication in the lower respiratory tract was noted on day 2 postinfection (p.i.) and was cleared by day 7 p.i. Low levels of virus were present in the nasal turbinates of a few hamsters at 14 days p.i. Viral replication in epithelial cells of the respiratory tract was accompanied by cellular necrosis early in infection, followed by an inflammatory response coincident with viral clearance, focal consolidation in pulmonary tissue, and eventual pulmonary tissue repair. Despite high levels of virus replication and associated pathology in the respiratory tract, the hamsters showed no evidence of disease. Neutralizing antibodies were detected in sera at day 7 p.i., and mean titers at day 28 p.i. exceeded 1:400. Hamsters challenged with SARS CoV at day 28 p.i. were completely protected from virus replication and accompanying pathology in the respiratory tract. Comparing these data to the mouse model, SARS CoV replicates to a higher titer and for a longer duration in the respiratory tract of hamsters and is accompanied by significant pathology that is absent in mice. Viremia and extrapulmonary spread of SARS CoV to liver and spleen, which are seen in hamsters, were not detected in mice. The hamster, therefore, is superior to the mouse as a model for the evaluation of antiviral agents and candidate vaccines against SARS CoV replication.

scholarly journals Collaboration between the Fab and Fc contribute to maximal protection against SARS-CoV-2 in nonhuman primates following NVX-CoV2373 subunit vaccine with Matrix-M™ vaccination

2021 ◽  
Author(s):  
Matthew J Gorman ◽  
Nita Patel ◽  
Mimi Guebre-Xabier ◽  
Alex Zhu ◽  
Caroline Atyeo ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Neutralizing Antibodies ◽  
Lower Respiratory Tract ◽  
Subunit Vaccine ◽  
List Type ◽  
Antigen Dose ◽  
Virus Shedding ◽  
Effector Functions ◽  
Humoral Immune ◽  
Functional Antibodies

AbstractRecently approved vaccines have already shown remarkable protection in limiting SARS-CoV-2 associated disease. However, immunologic mechanism(s) of protection, as well as how boosting alters immunity to wildtype and newly emerging strains, remain incompletely understood. Here we deeply profiled the humoral immune response in a cohort of non-human primates immunized with a stable recombinant full-length SARS-CoV-2 spike (S) glycoprotein (NVX-CoV2373) at two dose levels, administered as a single or two-dose regimen with a saponin-based adjuvant Matrix-M™. While antigen dose had some effect on Fc-effector profiles, both antigen dose and boosting significantly altered overall titers, neutralization and Fc-effector profiles, driving unique vaccine-induced antibody fingerprints. Combined differences in antibody effector functions and neutralization were strongly associated with distinct levels of protection in the upper and lower respiratory tract, pointing to the presence of combined, but distinct, compartment-specific neutralization and Fc-mechanisms as key determinants of protective immunity against infection. Moreover, NVX-CoV2373 elicited antibodies functionally target emerging SARS-CoV-2 variants, collectively pointing to the critical collaborative role for Fab and Fc in driving maximal protection against SARS-CoV-2. Collectively, the data presented here suggest that a single dose may prevent disease, but that two doses may be essential to block further transmission of SARS-CoV-2 and emerging variants.HighlightsNVX-CoV2373 subunit vaccine elicits receptor blocking, virus neutralizing antibodies, and Fc-effector functional antibodies.The vaccine protects against respiratory tract infection and virus shedding in non-human primates (NHPs).Both neutralizing and Fc-effector functions contribute to protection, potentially through different mechanisms in the upper and lower respiratory tract.Both macaque and human vaccine-induced antibodies exhibit altered Fc-receptor binding to emerging mutants.

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