key: cord-1038185-c0cpx2q3
authors: Opriessnig, Tanja; Huang, Yao‐Wei
title: Update on possible animal sources for COVID‐19 in humans
date: 2020-06-17
journal: Xenotransplantation
DOI: 10.1111/xen.12621
sha: 99040d224b292a39d39e83c3aab8bac817043580
doc_id: 1038185
cord_uid: c0cpx2q3

nan

Since our commentary on the likelihood of pigs transmitting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to humans published in March 2020, 1 

has upgraded SARS-CoV-2 infection to a global pandemic (https:// www.who.int/dg/speec hes/detai l/who-direc tor-gener al-s-openi ng-remar ks-at-the-media -brief ing-on-covid -19--- 11-march -2020) and the virus has spread to all continents with direct impact in most countries. Updated SARS-CoV-2 data in humans are provided in Table 1 . This synopsis summarizes the latest findings on animal sources that could pose a risk for human SARS-CoV-2 infection and hence may be important during xenotransplantation.

The novel SARS-CoV-2 was initially observed with severe lung disease designated as coronavirus disease 2019 in a cluster of patients in Wuhan, Hubei Province in China during December 2019. 2 Coronavirus species typically cause respiratory and gastrointestinal sickness in both humans and animals. 3 It is recognized that SARS-CoV-2 can be transmitted through aerosols and direct or indirect contact. [4] [5] [6] However, the role of animals in human infections is less clear. One of the earliest published studies investigating the ability of SARS-CoV-2 to replicate in various animal species found that the virus does not infect farm animals including pigs, chickens, and ducks. 7 In support of these early results, an ongoing study conducted at the Friedrich Loeffler Institute in Germany further confirmed that pigs and chickens are not susceptible to intranasal infection with SARS-CoV-2 (https://prome dmail.org/prome d-post/?id=7196506). Results from experimental infection trials are summarized in Table 2 . Furthermore, a large Chinese study inves- It appears that ferrets, cats and to some degree also dogs are permissive to SARS-CoV-2 infection. In ferrets, experimental infection resulted in virus replication in the upper respiratory tract for up to 8 days without clinical signs or mortality. 7 These findings were essentially confirmed by other groups who also established that naïve ferrets can be infected via contact exposure (https://prome dmail.org/prome d-post/?id=7196506) or airborne transmission. 9, 10 Furthermore, minks with naturally acquired SARS-CoV-2 infection have been identified (Table 3) confirming that the Mustelidae family, which includes ferrets, minks but also weasels, badgers, and otters, appears susceptible to SARS-CoV-2 infection.

Evidence that pets may be susceptible to SARS-CoV-2 arose first via an experimental infection trial. 7 Specifically, 2-6 months old cats were intranasally inoculated with SARS-CoV-2 and viral RNA was detected in the respiratory tract 6 days post-infection. When the cats were placed in contact with uninfected cats, SARS-CoV-2 transmission occurred after 3 days and antibodies against SARS-CoV-2 were detected in infected and exposed cats ( Table 2) . 7 Similar findings were reproduced in US cats recently. 11 Additional accumulated evidence during a seroprevalence study further supports that SARS-CoV-2 is indeed capable of entering the feline population. 12 The susceptibility of dogs to SARS-CoV-2 has also been investigated.

After experimental infection they may become infected at a low level with limited transmission. 7 Natural infection, as evidenced by the presence of antibodies, SARS-CoV-2 RNA or both, has been identified in selected dogs in close contact with COVID-19 patients (Table 3) . A recent French study, which investigated nine cats and 12 dogs in close contact with a cluster of COVID-19 patients, was unable to detect evidence of SARS-CoV-2 infection in any of the animals. 13 Finally, the Chinese serosurveillance study that investigated farm animals also tested serum samples from 487 dogs and 87 cats collected between November 2019 and March 2020. 8 All samples were negative for SARS-CoV-2 antibodies, 8 in accordance with the French study. 13 In summary, since SARS-CoV-2 emerged in the human population towards the end of 2019, it has been spreading at a high rate. There is strong evidence that SARS-CoV-2 from COVID-19 infected humans can spillover to animal species within the families Mustelidae, Felinae, and Caninae. Infections are frequently subclinical but occasional clinical signs can be observed (Table 3 ). Based on available serological surveys, these are likely localized rare events; the true extent of human-to-animal infections requires further investigations. Moreover, animal-to-human SARS-CoV-2 infection as well as natural animal-to-animal transmission has yet to be confirmed and none of the species considered to be susceptible to the virus at this point are presently used for xenotransplantation.

Despite not being affected by SARS-CoV-2 directly, pigs are being used to test novel SARS-CoV-2 vaccines for possible human use (https://www.pirbr ight.ac.uk/news/2020/03/pirbr ight-begin s-testi ng-new-coron aviru s-vacci nes-anima ls-help-comba t-covid -19). 

Coronavirus disease 2019 (COVID-19) outbreak: could pigs be vectors for human infections?

Clinical features of patients infected with 2019 novel coronavirus in Wuhan

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2): an update

Transmission routes of 2019-nCoV and controls in dental practice

Early epidemiological and clinical characteristics of 28 cases of coronavirus disease in South Korea

COVID-19 vulnerability: the potential impact of genetic susceptibility and airborne transmission

Susceptibility of ferrets, cats, dogs, and other domesticated animals to SARS-coronavirus 2

Serological survey of SARS-CoV-2 for experimental, domestic, companion and wild animals excludes intermediate hosts of 35 different species of animals

Infection and rapid transmission of SARS-CoV-2 in ferrets

SARS-CoV-2 is transmitted via contact and via the air between ferrets

Transmission of SARS-CoV-2 in domestic cats

SARS-CoV-2 neutralizing serum antibodies in cats: a serological investigation

Absence of SARS-CoV-2 infection in cats and dogs in close contact with a cluster of COVID-19 patients in a veterinary campus

Infection of dogs with SARS-CoV-2

How to cite this article: Opriessnig T, Huang Y-W. Update on possible animal sources for COVID-19 in humans