From people toPanthera: Natural SARS-CoV-2 infection in tigers and lions at the Bronx Zoo

Abstract

We describe the first cases of natural SARS-CoV-2 infection detected in animals in the United States. In March 2020, four tigers and three lions at the Bronx Zoo developed mild respiratory signs. SARS-CoV-2 RNA was detected by rRT-PCR in respiratory secretions and/or feces from all seven affected animals; viral RNA and/or antibodies were detected in their keepers. SARS-CoV-2 was isolated from respiratory secretions or feces from three affected animals; in situ hybridization co-localized viral RNA with cellular damage. Whole genome sequence and haplotype network analyses showed tigers and lions were infected with two different SARS-CoV-2 strains, suggesting independent viral introductions. The source of SARS-CoV-2 infection in the lions is unknown. Epidemiological data and genetic similarities between keeper and tiger viruses indicate human to animal transmission.

Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2): A Perspective Through the Lens of the Veterinary Diagnostic Laboratory

“…SARS-CoV-2 testing in animals is generally performed on nasopharyngeal swabs, fecal samples or rectal swabs (3, 5, 7-10, 12, 16, 19); testing on saliva may be an additional option in animals (9, 35). Fecal sampling is an appealing non-invasive collection method, allowing ready surveillance of at-risk wildlife or zoological animals, albeit at the risk of reduced sensitivity due to less viral RNA (16). Shedding periods may extend beyond the period of clinical signs, thus fecal testing may help us understand how long shedding persists, which will contribute to risk assessments and epidemiological investigations into transmission.…”

“…Domestic and non-domestic felids, dogs, ferrets, mink, non-human primates, and hamsters can be naturally or experimentally infected with the virus, with shedding of variable degree and duration and evidence of inter-individual transmission (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). Subsequent to the original animal-tohuman transmission event and resulting human-to-human transmission, the current infection paradigm is that companion and non-domestic farmed or captive animals acquire the virus from humans.…”

“…In humans, viral RNA can be found in feces and rarely in urine (36,41,43,44), with one report of infectious virus in feces (45). Viral RNA has been amplified from feces in domestic and wild felidae (12,16), feces and urine from ferrets (9) and feces from monkeys (46), with infectious virus being isolated from feces from non-domestic cats (16), ferrets (9), and monkeys (46). While feces, urine and blood may not contain as much intact virus as respiratory samples, they are still considered infectious, but likely pose a low risk to laboratory personnel.…”

“…False negative rRT-PCR results can be due to patient factors (e.g., intermittent shedding), sample collection (e.g., wrong timing, insufficient or inadequate specimens), sample handling (e.g., RNA degradation with storage), or test limitations (e.g., inadequate RNA extraction, insensitive primers, RNA levels below detection limits in early or low-level infections) (60)(61)(62). Viral RNA can be detected in situ using RNA hybridization and virus-specific probes in research studies (7,10,11,16,42). As for any laboratory test, it is critically important to include positive and negative controls and verify specificity for SARS-CoV-2 to prevent cross-reaction with other coronaviruses, minimize the likelihood of false positive or negative reactions and verify test performance.…”

“…In veterinary settings, the lack of species-specific secondary antibodies can be a major limitation for serologic testing. Thus, serum neutralization assays are often used to detect antibodies, especially when testing samples from non-domestic wildlife or zoological animals (16). Antibodies for immunologic testing should be thoroughly validated, as described for immunohistochemical staining (63).…”