Biology subjects

Saturday, G.

Publications and source records attributed to Saturday, G..

28 records · Page 2Linked to original sources

bioRxiv2021

Recovery from acute SARS-CoV-2 infection and development of anamnestic immune responses in T cell-depleted rhesus macaques

Severe COVID-19 has been associated with T cell lymphopenia 1,2, but no causal effect of T cell deficiency on disease severity has been established. To investigate the specific role of T cells in recovery from SARS-CoV-2 infections we studied rhesus macaques that were depleted of either CD4+, CD8+ or both T cell subsets prior to infection. Peak virus loads were similar in all groups, but the resolution of virus in the T cell-depleted animals was slightly delayed compared to controls. The T cell-depleted groups developed virus-neutralizing antibody responses and also class-switched to IgG. When re-infected six weeks later, the T cell-depleted animals showed anamnestic immune responses characterized by rapid induction of high-titer virus-neutralizing antibodies, faster control of virus loads and reduced clinical signs. These results indicate that while T cells play a role in the recovery of rhesus macaques from acute SARS-CoV-2 infections, their depletion does not induce severe disease, and T cells do not account for the natural resistance of rhesus macaques to severe COVID-19. Neither primed CD4+ or CD8+ T cells appeared critical for immunoglobulin class switching, the development of immunological memory or protection from a second infection.

immunology↗

bioRxiv2021

ChAdOx1 nCoV-19 (AZD1222) protects against SARS-CoV-2 B.1.351 and B.1.1.7

We investigated ChAdOx1 nCoV-19 (AZD1222) vaccine efficacy against SARS-CoV-2 variants of concern (VOCs) B.1.1.7 and B.1.351 in Syrian hamsters. We previously showed protection against SARS-CoV-2 disease and pneumonia in hamsters vaccinated with a single dose of ChAdOx1 nCoV-19. Here, we observed a 9.5-fold reduction of virus neutralizing antibody titer in vaccinated hamster sera against B.1.351 compared to B.1.1.7. Vaccinated hamsters challenged with B.1.1.7 or B.1.351 did not lose weight compared to control animals. In contrast to control animals, the lungs of vaccinated animals did not show any gross lesions. Minimal to no viral subgenomic RNA (sgRNA) and no infectious virus was detected in lungs of vaccinated animals. Histopathological evaluation showed extensive pulmonary pathology caused by B.1.1.7 or B.1.351 replication in the control animals, but none in the vaccinated animals. These data demonstrate the effectiveness of the ChAdOx1 nCoV-19 vaccine against clinical disease caused by B.1.1.7 or B.1.351 VOCs.

microbiology↗

bioRxiv2021

Mitophagy antagonism by Zika virus reveals Ajuba as a regulator of PINK1-Parkin signaling, PKR-dependent inflammation, and viral invasion of tissues.

Dysregulated inflammation dominated by chemokine expression is a key feature of disease following infection with the globally important human pathogens, Zika virus (ZIKV) and dengue virus, but a mechanistic understanding of how pro-inflammatory responses are initiated is lacking. Mitophagy is a quality control mechanism that regulates innate immune signaling and cytokine production through selective degradation of damaged mitochondria. Here, we demonstrate that ZIKV NS5 antagonizes mitophagy by binding to the host protein Ajuba and preventing its translocation to depolarized mitochondria where it is required for PINK1 activation and downstream signaling. Consequent mitophagy suppression amplified the production of pro-inflammatory chemokines through PKR sensing of mitochondrial RNA. In Ajuba-/- mice, ZIKV induced early expression of pro-inflammatory chemokines associated with significantly enhanced dissemination to tissues. This work identifies Ajuba as a critical regulator of mitophagy, and demonstrates a role for mitophagy in limiting systemic inflammation following infection by globally important human viruses.

microbiology↗

bioRxiv2021

Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces shedding of SARS-CoV-2 D614G in rhesus macaques

Intramuscular vaccination with ChAdOx1 nCoV-19/AZD1222 protected rhesus macaques against pneumonia but did not reduce shedding of SARS-CoV-2. Here we investigate whether intranasally administered ChAdOx1 nCoV-19 reduces shedding, using a SARS-CoV-2 virus with the D614G mutation in the spike protein. Viral load in swabs obtained from intranasally vaccinated hamsters was significantly decreased compared to controls and no viral RNA or infectious virus was found in lung tissue, both in a direct challenge and a transmission model. Intranasal vaccination of rhesus macaques resulted in reduced shedding and a reduction in viral load in bronchoalveolar lavage and lower respiratory tract tissue. In conclusion, intranasal vaccination reduced shedding in two different SARS-CoV-2 animal models, justifying further investigation as a potential vaccination route for COVID-19 vaccines.

microbiology↗

bioRxiv2020

Defining the Syrian hamster as a highly susceptible preclinical model for SARS-CoV-2 infection

Following emergence in late 2019, SARS-CoV-2 rapidly became pandemic and is presently responsible for millions of infections and hundreds of thousands of deaths worldwide. There is currently no approved vaccine to halt the spread of SARS-CoV-2 and only very few treatment options are available to manage COVID-19 patients. For development of preclinical countermeasures, reliable and well-characterized small animal disease models will be of paramount importance. Here we show that intranasal inoculation of SARS-CoV-2 into Syrian hamsters consistently caused moderate broncho-interstitial pneumonia, with high viral lung loads and extensive virus shedding, but animals only displayed transient mild disease. We determined the infectious dose 50 to be only five infectious particles, making the Syrian hamster a highly susceptible model for SARS-CoV-2 infection. Neither hamster age nor sex had any impact on the severity of disease or course of infection. Finally, prolonged viral persistence in interleukin 2 receptor gamma chain knockout hamsters revealed susceptibility of SARS-CoV-2 to adaptive immune control. In conclusion, the Syrian hamster is highly susceptible to SARS-CoV-2 making it a very suitable infection model for COVID-19 countermeasure development. One Sentence SummaryThe Syrian hamster is highly susceptible to SARS-CoV-2 making it an ideal infection model for COVID-19 countermeasure development.

microbiology↗

bioRxiv2020

Hydroxychloroquine Proves Ineffective in Hamsters and Macaques Infected with SARS-CoV-2

We remain largely without effective prophylactic/therapeutic interventions for COVID-19. Although many human clinical trials are ongoing, there remains a deficiency of supportive preclinical drug efficacy studies. Here we assessed the prophylactic/therapeutic efficacy of hydroxychloroquine (HCQ), a drug of interest for COVID-19 management, in two animal models. When used for prophylaxis or treatment neither the standard human malaria dose (6.5 mg/kg) nor a high dose (50 mg/kg) of HCQ had any beneficial effect on clinical disease or SARS-CoV-2 kinetics (replication/shedding) in the Syrian hamster disease model. Similarly, HCQ prophylaxis/treatment (6.5 mg/kg) did not significantly benefit clinical outcome nor reduce SARS-CoV-2 replication/shedding in the upper and lower respiratory tract in the rhesus macaque disease model. In conclusion, our preclinical animal studies do not support the use of HCQ in prophylaxis/treatment of COVID-19.One Sentence Summary Hydroxychloroquine prophylaxis/treatment showed no beneficial effect in SARS-CoV-2 hamster and macaque disease models.Competing Interest StatementThe authors have declared no competing interest.View Full Text

pharmacology and toxicology↗

bioRxiv2020

ChAdOx1 nCoV-19 vaccination prevents SARS-CoV-2 pneumonia in rhesus macaques

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) emerged in December 20191,2 and is responsible for the COVID-19 pandemic3. Vaccines are an essential countermeasure urgently needed to control the pandemic4. Here, we show that the adenovirus-vectored vaccine ChAdOx1 nCoV-19, encoding the spike protein of SARS-CoV-2, is immunogenic in mice, eliciting a robust humoral and cell-mediated response. This response was not Th2 dominated, as demonstrated by IgG subclass and cytokine expression profiling. A single vaccination with ChAdOx1 nCoV-19 induced a humoral and cellular immune response in rhesus macaques. We observed a significantly reduced viral load in bronchoalveolar lavage fluid and respiratory tract tissue of vaccinated animals challenged with SARS-CoV-2 compared with control animals, and no pneumonia was observed in vaccinated rhesus macaques. Importantly, no evidence of immune-enhanced disease following viral challenge in vaccinated animals was observed. ChAdOx1 nCoV-19 is currently under investigation in a phase I clinical trial. Safety, immunogenicity and efficacy against symptomatic PCR-positive COVID-19 disease will now be assessed in randomised controlled human clinical trials.

microbiology↗

bioRxiv2020

Clinical benefit of remdesivir in rhesus macaques infected with SARS-CoV-2

BackgroundEffective therapeutics to treat COVID-19 are urgently needed. Remdesivir is a nucleotide prodrug with in vitro and in vivo efficacy against coronaviruses. Here, we tested the efficacy of remdesivir treatment in a rhesus macaque model of SARS-CoV-2 infection. MethodsTo evaluate the effect of remdesivir treatment on SARS-CoV-2 disease outcome, we used the recently established rhesus macaque model of SARS-CoV-2 infection that results in transient lower respiratory tract disease. Two groups of six rhesus macaques were infected with SARS-CoV-2 and treated with intravenous remdesivir or an equal volume of vehicle solution once daily. Clinical, virological and histological parameters were assessed regularly during the study and at necropsy to determine treatment efficacy. ResultsIn contrast to vehicle-treated animals, animals treated with remdesivir did not show signs of respiratory disease and had reduced pulmonary infiltrates on radiographs. Virus titers in bronchoalveolar lavages were significantly reduced as early as 12hrs after the first treatment was administered. At necropsy on day 7 after inoculation, lung viral loads of remdesivir-treated animals were significantly lower and there was a clear reduction in damage to the lung tissue. ConclusionsTherapeutic remdesivir treatment initiated early during infection has a clear clinical benefit in SARS-CoV-2-infected rhesus macaques. These data support early remdesivir treatment initiation in COVID-19 patients to prevent progression to severe pneumonia.

microbiology↗

bioRxiv2020

A single dose of ChAdOx1 MERS provides broad protective immunity against a variety of MERS-CoV strains

Middle East respiratory syndrome coronavirus (MERS-CoV) continues to infect humans via the dromedary camel reservoir and can transmit between humans, most commonly via nosocomial transmission. Currently, no licensed vaccine is available. Previously we showed that vaccination of transgenic mice with ChAdOx1 MERS, encoding the MERS S protein, prevented disease upon lethal challenge. In the current study we show that rhesus macaques seroconverted rapidly after a single intramuscular vaccination with ChAdOx1 MERS. Upon MERS-CoV challenge vaccinated animals were protected against respiratory injury and pneumonia and had a reduction in viral load in lung tissue of several logs. Furthermore, we did not detect MERS-CoV replication in type I and II pneumocytes of ChAdOx1 MERS vaccinated animals. A prime-boost regimen of ChAdOx1 MERS boosted antibody titers, and viral replication was completely absent from the respiratory tract tissue of these rhesus macaques. Finally, we investigated the ability of ChAdOx1 MERS to protect against six different MERS-CoV strains, isolated between 2012 to 2018, from dromedary camels and humans in the Middle East and Africa. Antibodies elicited by ChAdOx1 MERS in rhesus macaques were able to neutralize all MERS-CoV strains. Vaccination of transgenic hDPP4 mice with ChAdOx1 MERS completely protected the animals against disease and lethality for all different MERS-CoV strains. The data support further clinical development of ChAdOx1 MERS supported by CEPI. One Sentence SummaryPrime-only vaccination with ChAdOx1 MERS provides protective immunity against HCoV-EMC/2012 replication in rhesus macaques, and a wide variety of MERS-CoV strains in mice.

microbiology↗

bioRxiv2020

Respiratory disease and virus shedding in rhesus macaques inoculated with SARS-CoV-2

An outbreak of a novel coronavirus, now named SARS-CoV-2, causing respiratory disease and a [~]2% case fatality rate started in Wuhan, China in December 2019. Following unprecedented rapid global spread, the World Health Organization declared COVID-19 a pandemic on March 11, 2020. Although data on disease in humans are emerging at a steady pace, certain aspects of the pathogenesis of SARS-CoV-2 can only be studied in detail in animal models, where repeated sampling and tissue collection is possible. Here, we show that SARS-CoV-2 causes respiratory disease in infected rhesus macaques, with disease lasting 8-16 days. Pulmonary infiltrates, a hallmark of human disease, were visible in lung radiographs of all animals. High viral loads were detected in swabs from the nose and throat of all animals as well as in bronchoalveolar lavages; in one animal we observed prolonged rectal shedding. Taken together, the rhesus macaque recapitulates moderate disease observed in the majority of human cases. The establishment of the rhesus macaque as a model of COVID-19 will increase our understanding of the pathogenesis of this disease and will aid development and testing of medical countermeasures.

microbiology↗