Volume 26, Number 12—December 2020
Dispatch
Experimental Infection of Cattle with SARS-CoV-2
Lorenz Ulrich, Kerstin Wernike, Donata Hoffmann, Thomas C. Mettenleiter, and Martin BeerComments to Author Author affiliation: Friedrich-Loeffler-Institut, Insel Riems, Germany Suggested citation for this article
Abstract We inoculated 6 cattle with severe acute respiratory syndrome coronavirus 2 and kept them together with 3 uninoculated cattle. We observed viral replication and specific seroreactivity in 2 inoculated animals, despite high levels of preexisting antibody titers against a bovine betacoronavirus. The in-contact animals did not become infected.
After spilling over from an unknown animal host to humans, a novel betacoronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019 (1,2) and induced a global pandemic. This virus, which causes coronavirus disease, was first identified in humans in Wuhan, China (3). Conversations on the role of livestock and wildlife species at the human-animal interface in disease emergence and dynamics focused on identifying susceptible species, potential reservoirs, and intermediate hosts. Natural or experimental infections have demonstrated the susceptibility of fruit bats (Rousettus aegyptiacus), ferrets, felids, dogs, and minks to the virus; however, pigs, chicken, and ducks are not susceptible (4–6). Besides ducks, chicken, and pigs, other major livestock species, including >1.5 billion cattle (Bos taurus), live with close contact with humans. Non-SARS-CoV-2 betacoronaviruses are widespread in bovines (7); seroprevalences reach up to 90% (8), but these infections are usually subclinical (7). However, whether any ruminant species are susceptible to SARS-CoV-2 infection or whether there is any cross-reactivity of antibodies against bovine coronaviruses (BCoVs) and SARS-CoV-2 is unknown. We examined the susceptibility of cattle to SARS-CoV-2 infection and characterized the course of infection.
The Study
snip...
Conclusions Our findings demonstrate that under experimental conditions cattle show low susceptibility to SARS-CoV-2 infection. This finding corresponds with a predicted medium susceptibility of cattle species on the basis of a computational modelling of their angiotensin-I-converting enzyme 2, the cellular receptor for SARS-CoV-2 (10).
We inoculated 6 cattle with SARS-CoV-2; of these animals, 2 later tested positive for the virus in PCR of nasal swab samples and show specific seroconversion by RBD-ELISA. Even though the genome loads detected in animal 768 at day 3 were low, there is evidence that this animal was confronted with real viral replication. RNA residues from inoculation are only detectable shortly after inoculation; here, the day 2 nasal swab tested repeatedly PCR negative. Furthermore, other studies using the same infection dose and vaporization device also found no residual RNA on day 2 (5). In addition, the low-level viral replication led to a slight, but detectable, serologic reaction in the applied ELISA (Figure, panel B).
In our study, we did not observe intraspecies transmission to in-contact cattle. Thus, we have no indication that cattle play any role in the human pandemic, and no reports of naturally infected bovines exist. Nevertheless, in regions with large cattle populations and high prevalence of SARS-CoV-2 infection in humans, such as the United States or countries in South America, close contact between livestock and infected animal owners or caretakers could cause anthropo-zoonotic infections of cattle, as has been already described for highly susceptible animal species such as minks, felids, and dogs (6,11). When assessing the risk for virus circulation within bovine populations, one should consider the age, husbandry practices, and underlying health conditions of the animals. Outbreak investigations might include cattle, particularly if direct contact has occurred between animals and persons infected with SARS-CoV-2. In addition to direct detection by PCR, serologic screenings with sensitive and specific ELISAs should also be taken into consideration. In this context, the wide distribution of BCoV is of special interest, especially because the presence of a preexisting coronavirus did not protect from infection with another betacoronavirus in this study. Double infections of individual animals might lead to recombination events between SARS-CoV-2 and BCoV, a phenomenon already described for other pandemic coronaviruses (12). A resulting chimeric virus, comprising characteristics of both viruses, could threaten human and livestock populations and should therefore be monitored.
Mr. Ulrich is a veterinarian and doctoral candidate at the Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany. His research interests include pathogenesis and prevention of zoonotic viruses.
https://wwwnc.cdc.gov/eid/article/2...3pICyi_HGo03qoxYHQNDdtIjLy1vtNHJF80dm7llSTv8U
Dispatch
Experimental Infection of Cattle with SARS-CoV-2
Lorenz Ulrich, Kerstin Wernike, Donata Hoffmann, Thomas C. Mettenleiter, and Martin BeerComments to Author Author affiliation: Friedrich-Loeffler-Institut, Insel Riems, Germany Suggested citation for this article
Abstract We inoculated 6 cattle with severe acute respiratory syndrome coronavirus 2 and kept them together with 3 uninoculated cattle. We observed viral replication and specific seroreactivity in 2 inoculated animals, despite high levels of preexisting antibody titers against a bovine betacoronavirus. The in-contact animals did not become infected.
After spilling over from an unknown animal host to humans, a novel betacoronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerged in December 2019 (1,2) and induced a global pandemic. This virus, which causes coronavirus disease, was first identified in humans in Wuhan, China (3). Conversations on the role of livestock and wildlife species at the human-animal interface in disease emergence and dynamics focused on identifying susceptible species, potential reservoirs, and intermediate hosts. Natural or experimental infections have demonstrated the susceptibility of fruit bats (Rousettus aegyptiacus), ferrets, felids, dogs, and minks to the virus; however, pigs, chicken, and ducks are not susceptible (4–6). Besides ducks, chicken, and pigs, other major livestock species, including >1.5 billion cattle (Bos taurus), live with close contact with humans. Non-SARS-CoV-2 betacoronaviruses are widespread in bovines (7); seroprevalences reach up to 90% (8), but these infections are usually subclinical (7). However, whether any ruminant species are susceptible to SARS-CoV-2 infection or whether there is any cross-reactivity of antibodies against bovine coronaviruses (BCoVs) and SARS-CoV-2 is unknown. We examined the susceptibility of cattle to SARS-CoV-2 infection and characterized the course of infection.
The Study
snip...
Conclusions Our findings demonstrate that under experimental conditions cattle show low susceptibility to SARS-CoV-2 infection. This finding corresponds with a predicted medium susceptibility of cattle species on the basis of a computational modelling of their angiotensin-I-converting enzyme 2, the cellular receptor for SARS-CoV-2 (10).
We inoculated 6 cattle with SARS-CoV-2; of these animals, 2 later tested positive for the virus in PCR of nasal swab samples and show specific seroconversion by RBD-ELISA. Even though the genome loads detected in animal 768 at day 3 were low, there is evidence that this animal was confronted with real viral replication. RNA residues from inoculation are only detectable shortly after inoculation; here, the day 2 nasal swab tested repeatedly PCR negative. Furthermore, other studies using the same infection dose and vaporization device also found no residual RNA on day 2 (5). In addition, the low-level viral replication led to a slight, but detectable, serologic reaction in the applied ELISA (Figure, panel B).
In our study, we did not observe intraspecies transmission to in-contact cattle. Thus, we have no indication that cattle play any role in the human pandemic, and no reports of naturally infected bovines exist. Nevertheless, in regions with large cattle populations and high prevalence of SARS-CoV-2 infection in humans, such as the United States or countries in South America, close contact between livestock and infected animal owners or caretakers could cause anthropo-zoonotic infections of cattle, as has been already described for highly susceptible animal species such as minks, felids, and dogs (6,11). When assessing the risk for virus circulation within bovine populations, one should consider the age, husbandry practices, and underlying health conditions of the animals. Outbreak investigations might include cattle, particularly if direct contact has occurred between animals and persons infected with SARS-CoV-2. In addition to direct detection by PCR, serologic screenings with sensitive and specific ELISAs should also be taken into consideration. In this context, the wide distribution of BCoV is of special interest, especially because the presence of a preexisting coronavirus did not protect from infection with another betacoronavirus in this study. Double infections of individual animals might lead to recombination events between SARS-CoV-2 and BCoV, a phenomenon already described for other pandemic coronaviruses (12). A resulting chimeric virus, comprising characteristics of both viruses, could threaten human and livestock populations and should therefore be monitored.
Mr. Ulrich is a veterinarian and doctoral candidate at the Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany. His research interests include pathogenesis and prevention of zoonotic viruses.
https://wwwnc.cdc.gov/eid/article/2...3pICyi_HGo03qoxYHQNDdtIjLy1vtNHJF80dm7llSTv8U
