Survey of peridomestic mammal susceptibility to SARS-CoV-2 infection
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Abstract
Wild animals have been implicated as the origin of SARS-CoV-2, but it is largely unknown how the virus affects most wildlife species and if wildlife could ultimately serve as a reservoir for maintaining the virus outside the human population. Here we show that several common peridomestic species, including deer mice, bushy-tailed woodrats, and striped skunks, are susceptible to infection and can shed the virus in respiratory secretions. In contrast, we demonstrate that cottontail rabbits, fox squirrels, Wyoming ground squirrels, black-tailed prairie dogs, house mice, and racoons are not susceptible to SARS-CoV-2 infection. Our work expands upon the existing knowledge base of susceptible species and provides evidence that human-wildlife interactions could result in continued transmission of SARS-CoV-2.
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Our take
This study, available as a preprint and thus not yet peer reviewed, evaluated the susceptibility of nine species of North American wildlife to SARS-CoV-2. The results show that deer mice, bushy-tailed woodrats, and striped skunks are susceptible to infection and shed virus over multiple days. While the experiment did not evaluate whether animals could transmit the virus to their contacts, these results indicate that several wild rodent and carnivore species (including mink) could become infected.
Study design
other
Study population and setting
To evaluate thee susceptibility of several wildlife species to SARS-CoV-2, animals of nine species were captured in three counties of northern Colorado, USA or were purchased from a private vendor: deer mice (Peromyscus maniculatus, n = 9), house mice …
Our take
This study, available as a preprint and thus not yet peer reviewed, evaluated the susceptibility of nine species of North American wildlife to SARS-CoV-2. The results show that deer mice, bushy-tailed woodrats, and striped skunks are susceptible to infection and shed virus over multiple days. While the experiment did not evaluate whether animals could transmit the virus to their contacts, these results indicate that several wild rodent and carnivore species (including mink) could become infected.
Study design
other
Study population and setting
To evaluate thee susceptibility of several wildlife species to SARS-CoV-2, animals of nine species were captured in three counties of northern Colorado, USA or were purchased from a private vendor: deer mice (Peromyscus maniculatus, n = 9), house mice (Mus musculus, n = 6), bushy-tailed woodrats (Neotoma cinerea, n = 6), Wyoming ground squirrels (Urocitellus elegans, n = 2), black-tailed prairie dogs (Cynomys ludovicianus, n = 9), fox squirrels (Sciurus niger, n = 3), cottontail rabbits (Sylvilagus sp., n = 3), striped skunks (Mephitis mephitis, n = 6), and raccoons (Procyon lotor, n = 3). Animals were inoculated intranasally with between 10^4.5 and 10^4.9 plaque forming units (PFU) of SARS-CoV-2. All species had 1-3 inoculated individuals that were sacrificied at 3 days post-infection (DPI) to assess viral shedding and pathology. Select species (deer mice, house mice, woodrats, prairie dogs, raccoons, skunks) had additional inoculated individuals sacrificed at DPI 7 and 28; serum was collected from animals at DPI 28 to test for neutralizing antibodies against SARS-CoV-2.
Summary of main findings
None of the species showed clinical signs of infection, including normal body temperatures measured in skunks and raccoons, and no gross lesions were found in any animals at the time of necropsy. Deer mice, bushy-tailed woodrats, and striped skunks were susceptible to SARS-CoV-2, shedding infectious virus orally for up to DPI 3 or 4. Virus was isolated from tissues collected from the upper respiratory tract and lungs; all three species showed mild pathology in necropsied lung tissues. Cottontail rabbits, fox squirrels, Wyoming ground squirrels, black-tailed prairie dogs, house mice, and raccoons were not susceptible to virus infection. Inoculated deer mice, woodrats, and skunks sacrificed at DPI 28 had neutralizing antibodies against SARS-CoV-2, while house mice, prairie dogs, and raccoons did not.
Study strengths
The study confirmed that all animals were seronegative for SARS-CoV-2 prior to inoculation. The presence of infectious virus shedding in inoculated animals (not just viral RNA) was tested using cell culture; results were confirmed via PCR on material collected from positive cell cultures.
Limitations
The high dose given to animals may not be representative of natural infections. The limited number of animals collected from one regional population may not be generalizable across the entire range of each species. Additionally, the methods did not evaluate the ability of inoculated animals to transmit the virus to naïve contacts. Thus, this experiment can only indicate that infection of peridomestic rodents and skunks may be possible. Finally, the authors did not test for the presence of other coronaviruses in animals that may have affected results, e.g., cross-reactivity of antibodies.
Value added
Humans may interact directly with peridomestic wildlife living nearby or inside human dwellings, or indirectly through their pets (e.g., cats hunting rodents, dogs and raccoons scavenging trash). Thus, there is concern that SARS-CoV-2 could be spread to wildlife and eventually establish ongoing transmission that could result in new zoonotic spillover of SARS-CoV-2. Previous analyses of the ACE2 receptor that binds to SARS-CoV-2 suggested that many carnivore and rodent species may be susceptible. These results confirm previous studies showing that deer mice were susceptible to infection and that house mice are not susceptible; the study represents the first experimental evaluation of susceptibility in seven other species.
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SciScore for 10.1101/2021.01.21.427629: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding Slides were read by a veterinary pathologist blinded to the treatments. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources Virus: SARS-CoV-2 virus strain WA1/2020WY96 was obtained from BEI Resources (Manassas, VA, USA), passaged twice in Vero E6 cells and stocks frozen at −80°C in Dulbecco’s Modified Eagle Medium (DMEM) with 5% fetal bovine serum and antibiotics. Vero E6suggested: RRID:CVCL_XD71)Viral assays: Virus isolation was performed on all oral swab, nasal swab and 3 DPI tissue samples by … SciScore for 10.1101/2021.01.21.427629: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Institutional Review Board Statement not detected. Randomization not detected. Blinding Slides were read by a veterinary pathologist blinded to the treatments. Power Analysis not detected. Sex as a biological variable not detected. Cell Line Authentication not detected. Table 2: Resources
Experimental Models: Cell Lines Sentences Resources Virus: SARS-CoV-2 virus strain WA1/2020WY96 was obtained from BEI Resources (Manassas, VA, USA), passaged twice in Vero E6 cells and stocks frozen at −80°C in Dulbecco’s Modified Eagle Medium (DMEM) with 5% fetal bovine serum and antibiotics. Vero E6suggested: RRID:CVCL_XD71)Viral assays: Virus isolation was performed on all oral swab, nasal swab and 3 DPI tissue samples by double overlay plaque assay on Vero cells as previously described (17). Verosuggested: CLS Cat# 605372/p622_VERO, RRID:CVCL_0059)Results 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.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
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