An alphavirus replicon-based vaccine expressing a stabilized Spike antigen induces sterile immunity and prevents transmission of SARS-CoV-2 between cats
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Abstract
Early in the global SARS-CoV-2 pandemic concerns were raised regarding infection of other animal hosts and whether these could play a significant role in the viral epidemiology. Infection of animals could be detrimental by causing clinical disease but also of concern if they become a viral reservoir allowing further mutations, plus having the potential to infect other animals or humans. The first reported animals to be infected both under experimental conditions and from anecdotal field evidence were cats described in China early in 2020. Given the concerns this finding raised and the close contacts between humans and cats, we aimed to determine whether a vaccine candidate could be developed that was suitable for use in multiple susceptible animal species and whether this vaccine could reduce infection of cats in addition to preventing spread to other cats.
Here we report that a Replicon Particle (RP) vaccine based on Venezuelan equine encephalitis virus (VEEV), known to be safe and efficacious for use in a variety of animals, expressing a stabilised Spike antigen, could induce neutralising antibody titers in guinea pigs and cats. After two intramuscular vaccinations, virus neutralising antibodies were detected in the respiratory tract of the guinea pigs and a cell mediated immune response was induced. The design of the SARS-CoV-2 antigen was shown to be critical in developing a strong neutralising antibody response. Vaccination of cats was able to induce a serum neutralising antibody response which lasted for the course of the experiment. Interestingly, in contrast to control animals, infectious virus could not be detected in oropharyngeal or nasal swabs of vaccinated cats after challenge. Moreover, the challenged control cats spread the virus to in-contact cats whereas the vaccinated cats did not transmit virus. The results show that the RP vaccine induces sterile immunity preventing SARS-CoV-2 infection and transmission. This data suggests that this RP vaccine could be a multi-species vaccine useful for preventing spread to and between other animals should that approach be required.
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SciScore for 10.1101/2021.04.01.436305: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization Animals and husbandry: Female SPF guinea pigs (Dunkin Hartley) were obtained from Envigo at a minimum weight of 350 grams, randomly allocated to experimental groups and individually marked using color coded tags. Blinding not detected. Power Analysis not detected. Sex as a biological variable Domestic short hair male and female SPF cats were obtained from Marshall BioResources (Waverly, NY), identified by microchip and randomly allocated to experimental groups. Cell Line Authentication not detected. Table 2: Resources
Antibodies Sentences Resources After incubation, the cells were fixed and stained with the primary antibody (anti-VEEV nsp2 … SciScore for 10.1101/2021.04.01.436305: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization Animals and husbandry: Female SPF guinea pigs (Dunkin Hartley) were obtained from Envigo at a minimum weight of 350 grams, randomly allocated to experimental groups and individually marked using color coded tags. Blinding not detected. Power Analysis not detected. Sex as a biological variable Domestic short hair male and female SPF cats were obtained from Marshall BioResources (Waverly, NY), identified by microchip and randomly allocated to experimental groups. Cell Line Authentication not detected. Table 2: Resources
Antibodies Sentences Resources After incubation, the cells were fixed and stained with the primary antibody (anti-VEEV nsp2 monoclonal antibody) followed by a FITC conjugated anti-murine IgG secondary antibody. anti-VEEV nsp2suggested: Noneanti-murine IgGsuggested: NoneELISA for estimating anti RBD and SED antibody titers in sera: Purified SARS-CoV-2 RBD and SED (Spike ectodomain) were diluted in DPBS (without Ca and Mg, Lonza, 17-512F) and coated onto 96-well plates (MaxiSorp - ThermoFisher or High binding - Greiner Bio-one) using 10nM (10 pmols/mL), and incubated overnight at 4°C. anti RBDsuggested: None17-512Fsuggested: NonePlates were washed again 3 times before being incubated with the HRP-containing antibody – Goat anti-Guinea pig (IgG-HRPO, Jackson Lab 106-035-003, 1:8000) for 1 hour at RT. anti-Guinea pig ( IgG-HRPOsuggested: NoneExperimental Models: Cell Lines Sentences Resources The virus was propagated for one passage on Vero cells. Verosuggested: CLS Cat# 605372/p622_VERO, RRID:CVCL_0059)Confluent monolayers of Vero E6 cells in 6 well plates were washed once with PBS and seeded with 100ul of serial ten-fold dilutions of swab/wash samples, incubated at 37°C for one hour then overlaid with 0.5% agarose in MEM containing 2% FBS. Vero E6suggested: NoneResults from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- No funding statement was detected.
- No protocol registration statement was detected.
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