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1.
Viruses ; 14(3)2022 03 06.
Article in English | MEDLINE | ID: covidwho-1786061

ABSTRACT

The emergence of SARS-CoV-2 in the human population and the resulting COVID-19 pandemic have led to the development of various diagnostic tests. The OraSure InteliSwab™ COVID-19 Rapid Test is a recently developed and FDA emergency use-authorized rapid antigen-detecting test that functions as a lateral flow device targeting the nucleocapsid protein. Due to SARS-CoV-2 evolution, there is a need to evaluate the sensitivity of rapid antigen-detecting tests for new variants, especially variants of concern such as Omicron. In this study, the sensitivity of the OraSure InteliSwab™ Test was investigated using cultured strains of the known variants of concern (VOCs, Alpha, Beta, Gamma, Delta, and Omicron) and the ancestral lineage (lineage A). Based on dilution series in cell culture medium, an approximate limit of detection for each variant was determined. The OraSure InteliSwab™ Test showed an overall comparable performance using recombinant nucleocapsid protein and different cultured variants, with recorded limits of detection ranging between 3.77 × 105 and 9.13 × 105 RNA copies/mL. Finally, the sensitivity was evaluated using oropharyngeal swabs from Syrian golden hamsters inoculated with the six VOCs. Ultimately, the OraSure InteliSwab™ COVID-19 Rapid Test showed no decrease in sensitivity between the ancestral SARS-CoV-2 strain and any VOCs including Omicron.


Subject(s)
COVID-19 , SARS-CoV-2 , COVID-19/diagnosis , Humans , Nucleocapsid Proteins/genetics , Pandemics , SARS-CoV-2/genetics
2.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-331333

ABSTRACT

To combat future SARS-CoV-2 variants and spillovers of SARS-like betacoronaviruses (sarbecoviruses) threatening global health, we designed mosaic nanoparticles presenting randomly-arranged sarbecovirus spike receptor-binding domains (RBDs) to elicit antibodies against conserved/relatively-occluded, rather than variable/immunodominant/exposed, epitopes. We compared immune responses elicited by mosaic-8 (SARS-CoV-2 and seven animal sarbecoviruses) and homotypic (only SARS-CoV-2) RBD-nanoparticles in mice and macaques, observing stronger responses elicited by mosaic-8 to mismatched (not on nanoparticles) strains including SARS-CoV and animal sarbecoviruses. Mosaic-8 immunization showed equivalent neutralization of SARS-CoV-2 variants including Omicron and protected from SARS-CoV-2 and SARS-CoV challenges, whereas homotypic SARS-CoV-2 immunization protected only from SARS-CoV-2 challenge. Epitope mapping demonstrated increased targeting of conserved epitopes after mosaic-8 immunization. Together, these results suggest mosaic-8 RBD-nanoparticles could protect against SARS-CoV-2 variants and future sarbecovirus spillovers.

3.
EuropePMC;
Preprint in English | EuropePMC | ID: ppcovidwho-327368

ABSTRACT

The emergence of SARS-CoV-2 in the human population and the resulting COVID-19 pandemic has led to the development of various diagnostic tests. The OraSure InteliSwab ® COVID-19 Rapid Test is a recently developed and FDA emergency use authorized rapid antigen-detecting test that functions as a lateral flow device targeting the nucleocapsid protein. Due to SARS-CoV-2 evolution, there is a need to evaluate the sensitivity of rapid antigen-detecting tests for new variants, especially variants of concern like Omicron. In this study, the sensitivity of the OraSure InteliSwab ® Test was investigated using cultured strains of the known variants of concern (VOCs, Alpha, Beta, Gamma, Delta, and Omicron) and the ancestral lineage (lineage A). Based on dilution series in cell culture medium, an approximate limit of detection for each variant was determined. The OraSure InteliSwab ® Test showed an overall comparable performance using recombinant nucleocapsid protein and different cultured variants with recorded limits of detection ranging between 3.77 × 10 5 and 9.13 × 10 5 RNA copies/mL. Finally, the sensitivity was evaluated using oropharyngeal swabs from Syrian golden hamsters inoculated with the 6 VOCs. Ultimately, the OraSure InteliSwab ® COVID-19 Rapid Test showed no decrease in sensitivity between the ancestral SARS-CoV-2 strain and any VOCs including Omicron.

4.
PLoS Pathog ; 18(2): e1009914, 2022 02.
Article in English | MEDLINE | ID: covidwho-1686113

ABSTRACT

As novel SARS-CoV-2 variants continue to emerge, it is critical that their potential to cause severe disease and evade vaccine-induced immunity is rapidly assessed in humans and studied in animal models. In early January 2021, a novel SARS-CoV-2 variant designated B.1.429 comprising 2 lineages, B.1.427 and B.1.429, was originally detected in California (CA) and it was shown to have enhanced infectivity in vitro and decreased antibody neutralization by plasma from convalescent patients and vaccine recipients. Here we examine the virulence, transmissibility, and susceptibility to pre-existing immunity for B 1.427 and B 1.429 in the Syrian hamster model. We find that both variants exhibit enhanced virulence as measured by increased body weight loss compared to hamsters infected with ancestral B.1 (614G), with B.1.429 causing the most marked body weight loss among the 3 variants. Faster dissemination from airways to parenchyma and more severe lung pathology at both early and late stages were also observed with B.1.429 infections relative to B.1. (614G) and B.1.427 infections. In addition, subgenomic viral RNA (sgRNA) levels were highest in oral swabs of hamsters infected with B.1.429, however sgRNA levels in lungs were similar in all three variants. This demonstrates that B.1.429 replicates to higher levels than ancestral B.1 (614G) or B.1.427 in the oropharynx but not in the lungs. In multi-virus in-vivo competition experiments, we found that B.1. (614G), epsilon (B.1.427/B.1.429) and gamma (P.1) dramatically outcompete alpha (B.1.1.7), beta (B.1.351) and zeta (P.2) in the lungs. In the nasal cavity, B.1. (614G), gamma, and epsilon dominate, but the highly infectious alpha variant also maintains a moderate size niche. We did not observe significant differences in airborne transmission efficiency among the B.1.427, B.1.429 and ancestral B.1 (614G) and WA-1 variants in hamsters. These results demonstrate enhanced virulence and high relative oropharyngeal replication of the epsilon (B.1.427/B.1.429) variant in Syrian hamsters compared to an ancestral B.1 (614G) variant.


Subject(s)
COVID-19/virology , SARS-CoV-2/pathogenicity , Animals , COVID-19/pathology , Disease Models, Animal , Female , Humans , Lung/pathology , Lung/virology , Male , Mesocricetus , Mutation , SARS-CoV-2/classification , SARS-CoV-2/genetics , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism , Virulence
5.
Life Sci Alliance ; 5(4)2022 04.
Article in English | MEDLINE | ID: covidwho-1637974

ABSTRACT

Advanced age is a key predictor of severe COVID-19. To gain insight into this relationship, we used the rhesus macaque model of SARS-CoV-2 infection. Eight older and eight younger macaques were inoculated with SARS-CoV-2. Animals were evaluated using viral RNA quantification, clinical observations, thoracic radiographs, single-cell transcriptomics, multiparameter flow cytometry, multiplex immunohistochemistry, cytokine detection, and lipidomics analysis at predefined time points in various tissues. Differences in clinical signs, pulmonary infiltrates, and virus replication were limited. Transcriptional signatures of inflammation-associated genes in bronchoalveolar lavage fluid at 3 dpi revealed efficient mounting of innate immune defenses in both cohorts. However, age-specific divergence of immune responses emerged during the post-acute phase. Older animals exhibited sustained local inflammatory innate responses, whereas local effector T-cell responses were induced earlier in the younger animals. Circulating lipid mediator and cytokine levels highlighted increased repair-associated signals in the younger animals, and persistent pro-inflammatory responses in the older animals. In summary, despite similar disease outcomes, multi-omics profiling suggests that age may delay or impair antiviral cellular immune responses and delay efficient return to immune homeostasis.


Subject(s)
Aging/immunology , COVID-19/immunology , COVID-19/veterinary , SARS-CoV-2/immunology , Acute Disease , Animals , Antibody Formation/immunology , Bronchoalveolar Lavage Fluid , COVID-19/complications , COVID-19/genetics , Cytokines/blood , Gene Expression Regulation , Gene Regulatory Networks , Genomics , Immunity, Cellular/genetics , Immunomodulation , Inflammation/complications , Inflammation/pathology , Lung/immunology , Lung/pathology , Lung/virology , Lymphoid Tissue/pathology , Macaca mulatta/immunology , Macaca mulatta/virology , Models, Biological , Single-Cell Analysis , T-Lymphocytes/immunology , Transcription, Genetic
6.
Nat Microbiol ; 7(2): 213-223, 2022 02.
Article in English | MEDLINE | ID: covidwho-1621245

ABSTRACT

The major transmission route for SARS-CoV-2 is airborne. However, previous studies could not elucidate the contribution between large droplets and aerosol transmission of SARS-CoV-2 and its variants. Here, we designed and validated an optimized transmission caging setup, which allows for the assessment of aerosol transmission efficiency at various distances. At a distance of 2 m, only particles of <5 µm traversed between cages. Using this setup, we investigated the relative efficiency of aerosol transmission between the SARS-CoV-2 Alpha variant (B.1.1.7) and lineage A in Syrian hamsters. Aerosol transmission of both variants was confirmed in all sentinels after 24 h of exposure as demonstrated by respiratory virus shedding and seroconversion. Productive transmission also occurred after 1 h of exposure, highlighting the efficiency of this transmission route. Interestingly, after donors were infected with a mix of both variants, the Alpha variant outcompeted the lineage A variant in an airborne transmission chain. Overall, these data indicate that a lower infectious dose of the Alpha variant, compared to lineage A, could be sufficient for successful transmission. This highlights the continuous need to assess emerging variants and the development for pre-emptive transmission mitigation strategies.


Subject(s)
COVID-19/transmission , SARS-CoV-2/genetics , Aerosols , Animals , COVID-19/virology , Female , Male , Mesocricetus , SARS-CoV-2/pathogenicity , Viral Load , Virus Shedding
7.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-294709

ABSTRACT

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.

8.
Emerg Infect Dis ; 27(12): 3052-3062, 2021 12.
Article in English | MEDLINE | ID: covidwho-1528794

ABSTRACT

Middle East respiratory syndrome coronavirus (MERS-CoV) infects humans and dromedary camels and is responsible for an ongoing outbreak of severe respiratory illness in humans in the Middle East. Although some mutations found in camel-derived MERS-CoV strains have been characterized, most natural variation found across MERS-CoV isolates remains unstudied. We report on the environmental stability, replication kinetics, and pathogenicity of several diverse isolates of MERS-CoV, as well as isolates of severe acute respiratory syndrome coronavirus 2, to serve as a basis of comparison with other stability studies. Although most MERS-CoV isolates had similar stability and pathogenicity in our experiments, the camel-derived isolate C/KSA/13 had reduced surface stability, and another camel isolate, C/BF/15, had reduced pathogenicity in a small animal model. These results suggest that although betacoronaviruses might have similar environmental stability profiles, individual variation can influence this phenotype, underscoring the need for continual global viral surveillance.


Subject(s)
COVID-19 , Middle East Respiratory Syndrome Coronavirus , Aerosols , Animals , Camelus , Humans , Middle East Respiratory Syndrome Coronavirus/genetics , SARS-CoV-2 , Virulence , Zoonoses
9.
[Unspecified Source]; 2020.
Preprint in English | [Unspecified Source] | ID: ppcovidwho-292809

ABSTRACT

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 10 (4) TCID (50) or 10 (5) TCID (50) , the SARS-CoV-2 infection resulted in rapid weight loss in both groups and uniform lethality in the 10 (5) TCID (50) 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. Taken together, this suggests that this mouse model can be useful for studies of pathogenesis and medical countermeasure development. AUTHORS SUMMARY: The disease manifestation of COVID-19 in humans range from asymptomatic to severe. While several mild to moderate disease models have been developed, there is still a need for animal models that recapitulate the severe and fatal progression observed in a subset of patients. Here, we show that humanized transgenic mice developed dose-dependent disease when inoculated with SARS-CoV-2, the etiological agent of COVID-19. The mice developed upper and lower respiratory tract infection, with virus replication also in the brain after day 3 post inoculation. The pathological and immunological diseases manifestation observed in these mice bears resemblance to human COVID-19, suggesting increased usefulness of this model for elucidating COVID-19 pathogenesis further and testing of countermeasures, both of which are urgently needed.

10.
Sci Adv ; 7(43): eabj3627, 2021 Oct 22.
Article in English | MEDLINE | ID: covidwho-1483968

ABSTRACT

The emergence of several SARS-CoV-2 variants has caused global concerns about increased transmissibility, increased pathogenicity, and decreased efficacy of medical countermeasures. Animal models can be used to assess phenotypical changes in the absence of confounding factors. Here, we compared variants of concern (VOC) B.1.1.7 and B.1.351 to a recent B.1 SARS-CoV-2 isolate containing the D614G spike substitution in the rhesus macaque model. B.1.1.7 behaved similarly to D614G with respect to clinical disease and replication in the respiratory tract. Inoculation with B.1.351 resulted in lower clinical scores, lower lung virus titers, and less severe lung lesions. In bronchoalveolar lavages, cytokines and chemokines were up-regulated on day 4 in animals inoculated with D614G and B.1.1.7 but not with B.1.351. In nasal samples, cytokines and chemokines were up-regulated only in the B.1.1.7-inoculated animals. Together, our study suggests that circulation under diverse evolutionary pressures favors transmissibility and immune evasion rather than increased pathogenicity.

11.
Nat Commun ; 12(1): 5868, 2021 10 07.
Article in English | MEDLINE | ID: covidwho-1462005

ABSTRACT

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 observe 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 do not lose weight compared to control animals. In contrast to control animals, the lungs of vaccinated animals do not show any gross lesions. Minimal to no viral subgenomic RNA (sgRNA) and no infectious virus can be detected in lungs of vaccinated animals. Histopathological evaluation shows 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.


Subject(s)
COVID-19 Vaccines/immunology , COVID-19/immunology , COVID-19/prevention & control , SARS-CoV-2/immunology , Administration, Intranasal , Amino Acid Substitution , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/virology , Female , Lung/immunology , Lung/pathology , Lung/virology , Mesocricetus , Spike Glycoprotein, Coronavirus/immunology , Vaccination
14.
Elife ; 102021 07 13.
Article in English | MEDLINE | ID: covidwho-1389776

ABSTRACT

Ambient temperature and humidity strongly affect inactivation rates of enveloped viruses, but a mechanistic, quantitative theory of these effects has been elusive. We measure the stability of SARS-CoV-2 on an inert surface at nine temperature and humidity conditions and develop a mechanistic model to explain and predict how temperature and humidity alter virus inactivation. We find SARS-CoV-2 survives longest at low temperatures and extreme relative humidities (RH); median estimated virus half-life is >24 hr at 10°C and 40% RH, but ∼1.5 hr at 27°C and 65% RH. Our mechanistic model uses fundamental chemistry to explain why inactivation rate increases with increased temperature and shows a U-shaped dependence on RH. The model accurately predicts existing measurements of five different human coronaviruses, suggesting that shared mechanisms may affect stability for many viruses. The results indicate scenarios of high transmission risk, point to mitigation strategies, and advance the mechanistic study of virus transmission.


Subject(s)
Hot Temperature , Humidity , Models, Biological , SARS-CoV-2/growth & development , Virus Inactivation , COVID-19 , Humans
15.
Emerg Infect Dis ; 27(9): 2301-2311, 2021 09.
Article in English | MEDLINE | ID: covidwho-1368386

ABSTRACT

After the first detection of Middle East respiratory syndrome coronavirus (MERS-CoV) in camels in Jordan in 2013, we conducted 2 consecutive surveys in 2014-2015 and 2017-2018 investigating risk factors for MERS-CoV infection among camel populations in southern Jordan. Multivariate analysis to control for confounding demonstrated that borrowing of camels, particularly males, for breeding purposes was associated with increased MERS-CoV seroprevalence among receiving herds, suggesting a potential route of viral transmission between herds. Increasing age, herd size, and use of water troughs within herds were also associated with increased seroprevalence. Closed herd management practices were found to be protective. Future vaccination strategies among camel populations in Jordan could potentially prioritize breeding males, which are likely to be shared between herds. In addition, targeted management interventions with the potential to reduce transmission between herds should be considered; voluntary closed herd schemes offer a possible route to achieving disease-free herds.


Subject(s)
Coronavirus Infections , Middle East Respiratory Syndrome Coronavirus , Animals , Camelus , Coronavirus Infections/epidemiology , Coronavirus Infections/veterinary , Jordan/epidemiology , Male , Risk Factors , Seroepidemiologic Studies
16.
Viruses ; 13(8)2021 08 19.
Article in English | MEDLINE | ID: covidwho-1367918

ABSTRACT

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 at two and four weeks after prime vaccination. Two weeks after boost vaccination, binding but no neutralizing antibodies were detected in four out of six non-human primates. SARS-CoV-2 S protein-specific T cell responses were detected in these four animals. In conclusion, prime-boost vaccination with 4 µg of vaccine candidate CV07050101 resulted in limited immune responses in four out of six non-human primates.


Subject(s)
Antibodies, Viral/blood , COVID-19 Vaccines/immunology , Immunization, Secondary , Immunogenicity, Vaccine , SARS-CoV-2/immunology , Vaccines, Synthetic/immunology , Animals , Antibodies, Neutralizing/blood , COVID-19 Vaccines/administration & dosage , Immunity, Cellular , Immunization Schedule , Macaca mulatta , Male , Spike Glycoprotein, Coronavirus/immunology , T-Lymphocytes/immunology , Vaccines, Synthetic/administration & dosage
17.
Nat Commun ; 12(1): 4985, 2021 08 17.
Article in English | MEDLINE | ID: covidwho-1361633

ABSTRACT

Transmission of SARS-CoV-2 is driven by contact, fomite, and airborne transmission. The relative contribution of different transmission routes remains subject to debate. Here, we show Syrian hamsters are susceptible to SARS-CoV-2 infection through intranasal, aerosol and fomite exposure. Different routes of exposure present with distinct disease manifestations. Intranasal and aerosol inoculation causes severe respiratory pathology, higher virus loads and increased weight loss. In contrast, fomite exposure leads to milder disease manifestation characterized by an anti-inflammatory immune state and delayed shedding pattern. Whereas the overall magnitude of respiratory virus shedding is not linked to disease severity, the onset of shedding is. Early shedding is linked to an increase in disease severity. Airborne transmission is more efficient than fomite transmission and dependent on the direction of the airflow. Carefully characterized SARS-CoV-2 transmission models will be crucial to assess potential changes in transmission and pathogenic potential in the light of the ongoing SARS-CoV-2 evolution.


Subject(s)
COVID-19/transmission , Fomites , Administration, Intranasal , Aerosols , Animals , COVID-19/blood , COVID-19/virology , Cytokines/blood , Female , High-Throughput Nucleotide Sequencing , Lung/virology , Mesocricetus , Nasal Cavity/virology , Particle Size , RNA, Viral/genetics , Respiratory System/virology , SARS-CoV-2/isolation & purification , Severity of Illness Index , Vaccination , Virus Replication , Virus Shedding
18.
Sci Transl Med ; 13(607)2021 08 18.
Article in English | MEDLINE | ID: covidwho-1329033

ABSTRACT

ChAdOx1 nCoV-19/AZD1222 is an approved adenovirus-based vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) currently being deployed globally. Previous studies in rhesus macaques revealed that intramuscular vaccination with ChAdOx1 nCoV-19/AZD1222 provided protection against pneumonia but did not reduce shedding of SARS-CoV-2 from the upper respiratory tract. Here, we investigated whether intranasally administered ChAdOx1 nCoV-19 reduces detection of virus in nasal swabs after challenging vaccinated macaques and hamsters with SARS-CoV-2 carrying a D614G mutation in the spike protein. Viral loads in swabs obtained from intranasally vaccinated hamsters were decreased compared to control hamsters, and no viral RNA or infectious virus was found in lung tissue after a direct challenge or after direct contact with infected hamsters. Intranasal vaccination of rhesus macaques resulted in reduced virus concentrations in nasal swabs and a reduction in viral loads in bronchoalveolar lavage and lower respiratory tract tissue. Intranasal vaccination with ChAdOx1 nCoV-19/AZD1222 reduced virus concentrations in nasal swabs in two different SARS-CoV-2 animal models, warranting further investigation as a potential vaccination route for COVID-19 vaccines.


Subject(s)
COVID-19 , SARS-CoV-2 , Animals , COVID-19 Vaccines , Cricetinae , Macaca mulatta , Vaccination , Virus Shedding
19.
mBio ; 12(4): e0150321, 2021 08 31.
Article in English | MEDLINE | ID: covidwho-1327616

ABSTRACT

Severe coronavirus disease 2019 (COVID-19) has been associated with T cell lymphopenia, 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 severe acute respiratory syndrome coronavirus 2 (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 that in controls. The T cell-depleted groups developed virus-neutralizing antibody responses and class switched to IgG. When reinfected 6 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+ nor CD8+ T cells appeared critical for immunoglobulin class switching, the development of immunological memory, or protection from a second infection. IMPORTANCE Patients with severe COVID-19 often have decreased numbers of T cells, a cell type important in fighting most viral infections. However, it is not known whether the loss of T cells contributes to severe COVID-19 or is a consequence of it. We studied rhesus macaques, which develop only mild COVID-19, similar to most humans. Experimental depletion of T cells slightly prolonged their clearance of virus, but there was no increase in disease severity. Furthermore, they were able to develop protection from a second infection and produced antibodies capable of neutralizing the virus. They also developed immunological memory, which allows a much stronger and more rapid response upon a second infection. These results suggest that T cells are not critical for recovery from acute SARS-CoV-2 infections in this model and point toward B cell responses and antibodies as the essential mediators of protection from re-exposure.


Subject(s)
Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/pathology , Immunologic Memory/immunology , Lymphopenia/immunology , SARS-CoV-2/immunology , Animals , CD4-Positive T-Lymphocytes/cytology , CD4-Positive T-Lymphocytes/immunology , CD8-Positive T-Lymphocytes/cytology , CD8-Positive T-Lymphocytes/immunology , COVID-19/immunology , Female , Lymphocyte Depletion/methods , Macaca mulatta/immunology , Male
20.
Emerg Microbes Infect ; 10(1): 1284-1292, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1268056

ABSTRACT

The circulation of SARS-CoV-2 has resulted in the emergence of variants of concern (VOCs). It is currently unclear whether the previous infection with SARS-CoV-2 provides protection against reinfection with VOCs. Here, we show that low dose aerosol exposure to hCoV-19/human/USA/WA-CDC-WA1/2020 (WA1, lineage A), resulted in a productive mild infection. In contrast, a low dose of SARS-CoV-2 via fomites did not result in productive infection in the majority of exposed hamsters and these animals remained non-seroconverted. After recovery, hamsters were re-exposed to hCoV-19/South African/KRISP-K005325/2020 (VOC B.1.351) via an intranasal challenge. Seroconverted rechallenged animals did not lose weight and shed virus for three days. They had a little infectious virus and no pathology in the lungs. In contrast, shedding, weight loss and extensive pulmonary pathology caused by B.1.351 replication were observed in the non-seroconverted animals. The rechallenged seroconverted animals did not transmit the virus to naïve sentinels via direct contact transmission, in contrast to the non-seroconverted animals. Reinfection with B.1.351 triggered an anamnestic response that boosted not only neutralizing titres against lineage A, but also titres against B.1.351. Our results confirm that aerosol exposure is a more efficient infection route than fomite exposure. Furthermore, initial infection with SARS-CoV-2 lineage A does not prevent heterologous reinfection with B.1.351 but prevents disease and onward transmission. These data suggest that previous SARS-CoV-2 exposure induces partial protective immunity. The reinfection generated a broadly neutralizing humoral response capable of effectively neutralizing B.1.351 while maintaining its ability to neutralize the virus to which the initial response was directed against.


Subject(s)
Broadly Neutralizing Antibodies/blood , COVID-19/immunology , Fomites/virology , SARS-CoV-2/pathogenicity , Sequence Analysis, RNA/methods , Animals , Antibodies, Viral/blood , COVID-19/transmission , COVID-19/virology , Chlorocebus aethiops , Cricetinae , Disease Models, Animal , Female , High-Throughput Nucleotide Sequencing , Humans , SARS-CoV-2/genetics , SARS-CoV-2/immunology , Seroconversion , Severity of Illness Index , Vero Cells , Viral Load , Virus Replication
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