CatNews

It was recently presented to the "bioRxiv" archive of biological sciences in the form of prepress and free access, a publication which assesses the possibility that cats could be the reservoir of the SARS-CoV-2.

The article entitled "Susceptibility of ferrets, cats, dogs, and different domestic animals to SARS-coronavirus-2" was written by a team from the Harbin Veterinary Research Institute & National High Containment Laboratory for Animal Diseases Control and Prevention from the People's Republic. Chinese. The authors (Jianzhong Shi, Zhiyuan Wen, Gongxun Zhong, Huanliang Yang, Chong Wang, Renqiang Liu, Xijun He, Lei Shuai, Ziruo Sun, Yubo Zhao, Libin Liang, Pengfei Cui, Jinliang Wang, Xianfeng Zhang, Yuntao Guan, Hualan Chen and Zhigao Bu) carried out their study to answer the following three questions:

1) Can widely spread viruses be transmitted to other animal species, and then these become reservoirs of infection?

2) SARS-CoV-2 infection has a broad clinical spectrum in humans, from mild infection to death, but how does the virus behave in other animals?

3) Given that efforts are being made to develop vaccines and antiviral drugs, which animals can be used more precisely to simulate the effectiveness of these control measures in humans?

As for cats, five 8-month-old domestic cats (almost adult cats) and (probably 5) young cats (70-100 days) were intranasally inoculated with 10 ^ 5 pfu CTan-H (SARS-CoV-2 ).

The ability of the virus to infect cats and be passed on to other uninfected but placed cats close to infected cats was assessed by detection of mRNA.

Substantially, after 6 days from inoculation, viral RNA was detected in the nasal turbinates, in the soft palates of all treated cats and in the trachea of some of these and in the small intestine of the others. The virus has also been found in the feces of some cats. The effect was most evident in young cats.

The infected cats were also able, in some cases, to infect the unvaccinated cats kept in another cage near the infected cats.
The authors stated that "In summary, the authors found that ferrets and cats are highly susceptible to SARS-CoV-2, dogs have low susceptibility, and livestock, including pigs, chickens and ducks, do not are susceptible to the virus. "

They concluded that "the cats we used in this study were non-cohabiting, and were highly susceptible to SARS-CoV-2, which replicated efficiently and transmitted to previously uninfected cats. The detection of SARS-CoV-2 in cats it should be considered as a support for the elimination of COVID-19 in humans ".

Considerations:

The work is deposited on bioRxiv, which is a free-access prepress archive for the biological sciences. Being pre-printed (i.e. articles not yet officially published), the works on bioRxiv are not subjected to peer-reviewing (i.e. expert review), therefore not checked in scientific content but only subjected to basic screening against plagiarism. Precisely because of the popularity of bioRxiv, several biology journals have updated their pre-press policies, making it clear that they do not even consider pre-presses as a "preliminary publication" for the purposes of Ingelfinger's rule. Therefore, this work cannot be considered a complete document, but only a presentation of some preliminary results. Furthermore, the paper does not provide details on the materials and methods and technique used to detect viral mRNA and primers, on the way possible contamination has been avoided (very common in this type of study), as well as the description of other important procedures, making the work non-exhaustive and only a suggestion for a more accurate and scrupulous research.

The group that carried out the study is a group of experts but, unfortunately, did not underline the limits of his research and pushed himself to an emphatic and inappropriate conclusion.

It is important to highlight the difference and the limits between an open access prepress archive without expert scientific review of the contents and an official Scientific Review which presents works with the obligation of accurate review before publication.

The study also presents a very limited number of animals, therefore lacking a reliable statistical approach; it is clearly not an epidemiological work and the experimental conditions are very different from those observed in real life; for example: the concentration of viruses used in work is very high and the mode of infection among cats is unclear.

Therefore, if we wanted to explain it through a similar case, this work is similar to the evidence of a second HCM mutation in Maine Coon cats, which, after being presented as a poster at a Congress, did not find reliable feedback after an investigation. more scrupulous and not a full paper publication.

Finally, a very important point is the experience of the previous SARS infection. Indeed, laboratory studies on SARS-CoV (the old SARS infection) have shown that cats can become infected and pass on the infection to other cats (under laboratory conditions), but during the previous SARS pandemic there was no an indication that the virus was widespread in domestic cats or that it was transmitted from cats to humans.

Sometimes, it is not clear to researchers the possible damage they can create by disclosing preliminary and unreliable results due to lack of data. Most people with cats lack the competence to understand the limitations and strengths of such a study, and magazines are also more interested in attracting readers than showing correct information. Therefore, an increase in animal abandonment can occur for no real reason.

To avoid this negative scenario, the reliable and prestigious Nature (magazine) has also published a letter to discuss the limit of the study presented. The editor's comment titled "Coronavirus can infect cats - dogs, not so much" makes it clear that scientists say it is unclear whether felines can spread the virus to people, so pet owners don't need to get caught by the panic. The editor pointed out that "none of the infected cats showed symptoms of disease, and that only one of the three felines exposed to infected animals caught the virus. This suggests that the virus may not be highly transmissible in cats." "Furthermore, the modality of transmission is unclear because the study does not describe how the cages were set up and uninfected cats could have contracted the virus from contaminated feces or urine." Furthermore, "there is no direct evidence that infected cats have secreted enough coronavirus to pass it on to people." In addition, citing Prof. Dirk Pfeiffer, an epidemiologist from the City University of Hong Kong, "Attention in the control of COVID-19 must therefore remain firmly focused on reducing the risk of human-to-human transmission".

To conclude: KEEP CALM and LOVE your CAT (the neighbor not so much)

Article by

Andrea Amaroli (Adjunct Professor PhD)
Elena Romeo (Assistant Professor PhD)