On April 1, the "Nature" website, entitled "
The New Coronavirus can infect cats, but not easy to infect dogs", reported a new update from the team of Chen Hualan and Bu Zhigao of the Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences the study.
The team investigated the susceptibility of ferrets and animals in close contact with humans to
SARS-CoV-2 (COVID-19). The results show that the new coronavirus has poor replication ability in dogs, pigs, chickens and ducks, but it can effectively replicate in ferrets and cats. They also found that
the new coronavirus can spread between cats through respiratory droplets.
The day before, a spokesman for the Hong Kong Agriculture, Fisheries and Conservation Department said that a local mixed-breed shorthair cat tested positive for the new coronavirus, causing widespread concern.
However, scientists said in an interview with Nature that it is still unclear whether cats can transmit the virus to humans, so cat owners do not need to panic.
Cat susceptibility is still to be studied
The above study by Harbin Veterinary Medicine was published on the preprint server bioRxiv on March 31. (Note: The paper on bioRxiv has not been peer-reviewed)
In the study, the researchers selected a total of two
SARS-CoV-2 strains: F13-E from the South China Seafood Market in Wuhan and CTan-H from an infected patient to test the susceptibility of the animals.
The researchers injected the virus into the noses of five domestic cats. Six days later, when two of the animals were euthanized, viral RNA and infectious virus particles were found in their upper respiratory tract.
The researchers placed the cage of the infected cat next to the cage of the unvaccinated cat. After some time, they detected viral RNA in cats that had not been vaccinated. Studies suggest that
SARS-CoV-2 can spread between cats through droplets in the air.
The authors pointed out that the surveillance of viruses in cats should be included in the prevention and control of
the new coronavirus pneumonia outbreak.
Some scientists say that this discovery is worthy of attention, but cat owners need not panic now. It is unclear whether animals infected with the virus can pass the virus to humans.
Linda Saif, a virologist at Ohio State University, said that these results are based on laboratory experiments. In the experiment, a few animals will be intentionally given high doses of SARS-CoV-2 virus, but it does not mean that in real life. Spread between people and pets.
"There is no direct evidence that there are enough coronavirus in the secretions of infected cats to pass the coronavirus to humans," Linda Saif said.
Linda Saif said that none of the infected cats showed symptoms of the disease, and only one of the three cats in contact with infected animals was infected with the virus. This indicates that the spread rate of the virus between cats may not be high. In addition, the mode of transmission is unclear. The study did not describe how the cages were set up, and uninfected cats may have been infected with COVID-19 from contaminated feces or urine.
"More testing is needed, including injecting cats with different doses of virus to see if they can pass the virus to other cats," Linda Saif said.
Dirk Pfeiffer, an epidemiologist at the University of Hong Kong, believes that cats should be considered in the prevention and control measures, but they are not the main factor in the spread of disease. The prevention and control of epidemic situation undoubtedly needs to continue to be firmly committed to reducing the risk of transmission between people.
Previously, research on the SARS virus that causes severe acute respiratory syndrome has shown that cats can be infected and transmitted to other cats. But there is no indication that the virus spreads widely in domestic cats or from cats to humans.
However, the US Centers for Disease Control and Prevention has given recommendations that people carrying the
2019 new coronavirus (COVID-19) should limit contact with pets, including avoiding pet petting, licking, and sharing food.
The virus's ability to infect dogs is weak
The author vaccinated five 3-month-old Beagle dogs with
SARS-CoV-2 virus. It was found that even beagle dogs who were positive for rectal swabs could not detect the virus in blood and other tissues and organs. The results of this study prove that SARS-CoV-2 has a weak ability to infect dogs.
The researchers used the same strategy to test the susceptibility of pigs, chickens and ducks to SARS-CoV-2. As a result, no virus was detected and the serum was negative. This indicates that pigs, chickens and ducks are not susceptible to SARS-CoV-2.
The author believes that cats and dogs have close contact with humans, and understanding their susceptibility to SARS-CoV-2 is important for the prevention and control of new coronary pneumonia.
"We have provided important implications for animal management of new coronaviruses and animal management in epidemic prevention and control." The author points out.
Ferrets are susceptible and can be used as animal models for vaccine drug development
Ferrets are often used as animal models of human respiratory virus infection, so the Harvard veterinary research team tested the susceptibility of SARS-CoV-2 in ferrets. They inoculated SARS-CoV-2 intranasally to ferrets and euthanized them 4 days later.
The turbinates, soft palate, tonsils, trachea, lung, heart, spleen, kidney, pancreas, small intestine, brain, liver and other organs of each ferret were then tested for viral load. The results show that SARS-CoV-2 can replicate in the upper airway of ferrets, but cannot replicate in other organs.
At the same time, it is worth noting that SARS-CoV-2 can replicate in ferrets for up to 8 days without causing serious illness or death.
The author believes that the fact that SARS-CoV-2 efficiently replicates in the upper respiratory tract of ferrets can make ferrets a candidate animal model for testing potential vaccines and drugs. In fact, ferrets have been used as models for influenza research, and some laboratories have begun to use them for
COVID-19 research.
