ABSTRACT: Neutralizing monoclonal antibodies that target the spike receptor binding domain confer Fc-independent protection against SARS-CoV-2 infection in Syrian hamsters
Project description:SARS-CoV-2 has spread globally and caused the COVID-19 pandemic. Although passively delivered neutralizing antibodies against SARS-CoV-2 are in clinical trials, their mechanism of action in vivo is incompletely understood. Here, we define correlates of protection of neutralizing human monoclonal antibodies (mAbs) in SARS-CoV-2-infected mice. Whereas Fc effector functions are fully dispensable when mAbs are administered as prophylaxis, they are required for optimal protection as therapy. When given after infection, intact but not LALA-PG loss of Fc effector function variant mAbs reduce SARS-CoV-2 burden and lung disease in mice and hamsters. Fc engagement of neutralizing antibodies mitigates inflammation and improves respiratory mechanics, and transcriptional profiling suggests these phenotypes are associated with diminished innate immune signaling and enhanced tissue repair. Immune cell depletions establish that neutralizing mAbs require monocytes for therapeutic efficacy. Our study demonstrates that therapeutic neutralizing mAbs require Fc effector functions to reduce SARS-CoV-2 infection and modulate protective immune responses.
Project description:Hybrid immunity (vaccination + natural infection) to SARS-CoV-2 provides superior protection to re-infection. We performed immune profiling studies during breakthrough infections in mRNA-vaccinated hamsters to evaluate hybrid immunity induction. Vaccine was dosed to induce binding antibody titers against ancestral spike, but not efficient virus neutralization of ancestral SARS-CoV-2 or variants of concern (VoCs). Vaccination reduced morbidity and controlled lung virus titers for ancestral virus and Alpha but allowed breakthrough infections in Beta, Delta and Mu-challenged hamsters. Vaccination primed for T cell responses that were boosted by infection. Infection back-boosted neutralizing antibody responses against ancestral virus and VoCs. Hybrid immunity resulted in more cross-reactive sera, reflected by smaller antigenic cartography distances. Transcriptomics post infection reflects both vaccination status and disease course, and suggests a role for interstitial macrophages in vaccine-mediated protection. Therefore, protection by vaccination, even in the absence of neutralizing antibodies, correlates with recall of broadly reactive B- and T-cell responses.
Project description:Very few live attenuated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines are currently in pre-clinical or clinical development. We rationally attenuated SARS-CoV-2 (isolate WA1/2020) by removing the polybasic cleavage site within the spike protein and the open reading frames (ORFs) 6-8, and by introducing a pair of mutations into the non-structural protein 1 (Nsp1). The derived virus (WA1-DPRRA-ORF6-8-Nsp1K164A/H165A) became severely attenuated in both the K18-human ACE2 (hACE2) transgenic mice and in Syrian hamsters. Transcriptomic profiling of nasal turbinates and lung tissues of infected Syrian hamsters confirmed that WA1-DPRRA-ORF6-8-Nsp1K164A/H165A attenuated the upregulation of proinflammatory pathways. A single intranasal immunization of just 100 PFU of the WA1-DPRRA-ORF6-8-Nsp1K164A/H165A elicited binding and neutralizing antibody responses in Syrian hamsters and completely protected against SARS-CoV-2-induced weight loss and pneumonia. These data demonstrate the feasibility of rational attenuation of SARS-CoV-2. WA1-DPRRA-ORF6-8-Nsp1K164A/H165A represents a promising live attenuated vaccine candidate.
Project description:The COVID-19 pandemic prompted an unprecedented effort to develop effective countermeasures against SARS-CoV-2. While efficacious vaccines and certain therapeutic monoclonal antibodies are available, here, we report the development, cryo-EM structures and functional analyses of distinct potent monoclonal antibodies (mAbs) that neutralize SARS-CoV-2 and its variant B.1.351. We established a platform for rapid identification of highly potent and specific SARS-CoV-2-neutralizing antibodies by high-throughput B cell receptor single cell sequencing of spike receptor binding domain immunized animals. We identified two highly potent and specific SARS-CoV-2 neutralizing mAb clones that have single-digit nanomolar affinity and low-picomolar avidity. We also generated a bispecific antibody of these two lead clones. The lead monospecific and bispecific antibodies showed strong neutralization ability against prototypical SARS-CoV-2 and the highly contagious South African variant B.1.351 that post a further risk of reducing the efficacy of currently available therapeutic antibodies and vaccines. The lead mAbs showed potent in vivo efficacy against authentic SARS-CoV-2 in both prophylactic and therapeutic settings. We solved five cryo-EM structures at ~3 resolution of these neutralizing antibodies in complex with the ectodomain of the prefusion spike trimer, and revealed the molecular epitopes, binding patterns and conformations between the antibodies and spike RBD, which are distinct from existing antibodies. Our recently developed antibodies expand the repertoire of the toolbox of COVID-19 countermeasures against the SARS-CoV-2 pathogen and its emerging variants.
Project description:Syrian golden hamsters exhibit features of severe disease after SARS-CoV-2 challenge and are therefore useful models of COVID-19 pathogenesis and prevention with vaccines. Recent studies have shown that SARS-CoV-2 infection stimulates type I interferon, myeloid, and inflammatory signatures similar to human disease, and that weight loss can be prevented with vaccines. However, the impact of vaccination on transcriptional programs associated with COVID-19 pathogenesis and protective adaptive immune responses is unknown. Here we show that SARS-CoV-2 challenge in hamsters stimulates myeloid and inflammatory programs as well as signatures of complement and thrombosis associated with human COVID-19. Notably, single-dose immunization with Ad26.COV2.S, an adenovirus serotype 26 vector (Ad26)-based vaccine expressing a stabilized SARS-CoV-2 spike protein, prevents the upregulation of these pathways such that the gene expression profiles of vaccinated hamsters are comparable to uninfected animals. Furthermore, we validated the protective efficacy of the Ad26.COV2.S against proinflammatory pathways and coagulation cascade in rhesus macaques by proteomics. Finally, we show that Ad26.COV2.S vaccination induces T and B cell signatures that correlate with binding and neutralizing antibody responses. These data provide further insights into the mechanisms of Ad26.COV2.S based protection against severe COVID-19 in hamsters.
Project description:Using microarray analyses and subsequent verification by RT-PCR, we studied the changes in gene expression in the inferior colliculus after an ictal event in one models of audiogenic epilepsy, genetic audiogenic seizure hamster (GASH:Sal). GASH:Sal, a hamster strain developed at the University of Salamanca, exhibits genetic audiogenic epilepsy similar to human Grand Mal epilepsy. GASH:Sal shows an autosomal recessive inheritance for susceptibility to audiogenic seizures, which manifest more severely in young animals; the seizure severity progressively declines with age. Genetic animal models of epilepsy are an important tool for further understanding the basic cellular mechanisms underlying epileptogenesis and for developing novel antiepileptic drugs. We conducted a comparative study of gene expression in the inferior colliculus, a nucleus that triggers audiogenic seizures, using two animal models, the Wistar audiogenic rat (WAR) and the genetic audiogenic seizure hamster (GASH:Sal). For this purpose, both models were subjected to auditory stimulation, and 60 minutes after stimulation, the inferior colliculi were collected. As a control, intact Wistar rats and Syrian hamsters were subjected to identical stimulation and tissue preparation protocols to those performed on the experimental animals. A total of 24 animals were used in this study according to the following distribution: 12 control Syrian hamsters (Mesocricetus auratus) and 12 GASH:Sal at 16 weeks of age and a body weight of approximately 60 g. Six animals Syrian and GASH:Sal hamsters, respectively, were exposed to auditory stimulation, and 60 min after the seizures, we harvested the IC for all gene expression analyses (stimulated Syrian hamsters and stimulated GASH:Sal hamsters). As controls, other six animals Syrian and GASH:Sal hamsters, respectively, were not exposed to the same stimulation (Syrian hamsters and GASH:Sal hamsters).
Project description:We tested if Brd2 inhibitor ABBV-744 could reduce SARS-CoV-2 infection in Syrian Hamsters. Three days post-infection, the lungs of hamsters were harvested and subjected to RNA-seq. Infected, but untreated, hamsters showed marked up-regulation of a number of genes including ISGs when compared to uninfected controls. In contrast, hamsters treated with ABBV-744 showed a down-regulation of ISG levels, confirming ABBV-744 activity. Thus, Brd2 inhibition can decrease SARS-CoV-2 infection in Syrian Hamsters.
Project description:1. The experiment was performed to assess if the newly discovered Syrian hamster specific anti-PD-L1 antibody could induce a biologically relevant change in transcriptome profile in the tumours. This would confirm that the antibody has functional properties. In the larger picture, the Syrian Hamster model is favored over the mouse model for the development of vaccines and testing of oncolytic viruses/immunotherapies. This is because the model is semi permissive to virus replication compared to the mouse model. We can therefore more reliably assess the efficacy of oncolytic virotherapies, mainly oncolysis and promoter specific transgene expression. Moreover, we wanted to test potential improvements to treatment outcomes when combining oncolytic virotherapy and immune checkpoint blockade. However, there are not many commercially available research tools specific to the Syrian Hamster. This is why we developed an in vivo compatible immune checkpoint inhibitor so that we could assess the combination therapy in the Syrian hamster model. Lastly, we also wanted to validate if we could assess the efficacy of the immunotherapies using biopsies from hamsters to remove unnecessary use of animals. 2. To do this, we engrafted one PDAC tumours on the right flank of Syrian hamsters using 5 x10E+6 HapT1 cells grown in culture. When tumours reached 4-5mm in diameter, the hamsters were injected intraperitoneally with either 300ug of IgG2a control or anti-PD-L1 (clone;11B12-1). Hamsters were treated 8 times and a tumour biopsy was taken one day before the last treatment. The biopsy was immediately stored in RNA-later until extraction with RNA mini kit (Qiagen).
Project description:Messenger RNA-based vaccines against COVID-19 induce a robust anti-SARS-CoV-2 antibody response with potent viral neutralization activity. Antibody effector functions is determined by its constant region subclasses as well as by its glycosylation patterns, but their role in vaccine efficacy is not well understood. Moreover, whether vaccination induce antibodies with similar Fc structures and protection potential as in COVID-19 patients remains unclear. Here, we analyzed BNT162b2 vaccine-induced IgG subclass distribution and Fc glycosylation patterns, as well as their potential to drive effector function via Fc-gamma receptors and complement pathways. We identified a unique Fc composition of these antiviral protein antibodies that is distinct from COVID-19 patients and convalescences. Vaccine-induced anti-spike SARS-CoV-2 IgG displayed a pro-inflammatory Fc profile and superior Fab- and Fc-mediated function, as compared to antibodies generated during natural viral infection. Moreover, differences in the kinetics of IgG Fc structure formation and their engagement with immune receptors were observed between different age groups. These data highlight the heterogeneity of the IgG Fc response to SARS-CoV-2 infection and vaccination and suggest that they differently support long-lasting protection.
Project description:Since December 2019, the novel human Coronavirus SARS-CoV-2 has spread globally, causing millions of deaths. Unprecedented efforts have enabled development and authorization of a range of vaccines, which reduce transmission rates and confer protection against the associated disease COVID-19. These vaccines are conceptually diverse, including e.g. classical adjuvanted whole-inactivated virus, viral vectors, and mRNA vaccines. We have analysed two prototypic model vaccines, the strongly TH1-biased measles vaccine-derived candidate MeVvac2-SARS2-S(H) and a TH2-biased Alum-adjuvanted, non-stabilized Spike protein side-by-side, for their ability to protect Syrian hamsters upon challenge with a low-passage SARS-CoV-2 patient isolate. The MeVvac2-SARS2-S(H) vaccine protected the hamsters from severe disease. In contrast, the protein vaccine induced vaccine-associated enhanced respiratory disease (VAERD) with massive infiltration of eosinophils into the lungs. Global RNA-Seq analysis of hamster lungs revealed reduced viral RNA and less host dysregulation in MeVvac2-SARS2-S(H) vaccinated animals, while S protein vaccination triggered enhanced host gene dysregulation when compared to unvaccinated control animals. Of note, mRNAs encoding the major eosinophil attractant CCL-11, the TH2 response-driving cytokine IL-19, as well as TH2-cytokines IL-4, IL-5, and IL-13 were exclusively up-regulated in the lungs of S protein vaccinated animals, consistent with previously described VAERD induced by RSV vaccine candidates. IL-4, IL-5, and IL-13 were also up-regulated in S-specific splenocytes after protein vaccination. Using scRNA-Seq, T cells and innate lymphoid cells were identified as the source of these cytokines, while CCL11 and IL-19 mRNAs was found in interstitial macrophages displaying an activated phenotype. Interestingly, the amount of viral reads in this macrophage population correlated with the abundance of Fc-receptor reads. These findings suggest that VAERD is triggered by induction of TH2-type helper cells secreting IL-4, IL-5, and IL-13, together with stimulation of macrophages dependent on Fc-receptor mediated uptake of virus complexed with non-neutralizing antibodies. Via this mechanism, uncontrolled eosinophil recruitment to the infected tissue occurs, a hallmark of VAERD immunopathogenesis. These effects could effectively be treated using dexamethasone and were not observed in animals vaccinated with MeVvac2-SARS2-S(H). Taken together, our data validate the potential for, and identify the transcriptional mediators that underlie VAERD and their cellular origins, in the context of protein-based TH2-biased COVID-19 vaccines. Dexamethasone, which is already in use for treatment of severe COVID-19, may alleviate such VAERD, but in-depth scrutiny of any next-generation protein-based vaccine candidates is required, prior and after their regulatory approval.