Pathogenesis, transmission and response to re exposure of SARS CoV 2 in domestic cats

The pandemic caused by SARS-CoV-2 has reached nearly every country in the world with extraordinary person-to-person transmission. The most likely original source of the virus was spillover from an animal reservoir and subsequent adaptation to humans sometime during the winter of 2019 in Wuhan Province, China. Because of its genetic similarity to SARS-CoV-1, it is likely that this novel virus has a similar host range and receptor specificity. Due to concern for human-pet transmission, we investigated the susceptibility of domestic cats and dogs to infection and potential for infected cats to transmit to naïve cats. We report that cats are highly susceptible to subclinical infection, with a prolonged period of oral and nasal viral shedding that is not accompanied by clinical signs, and are capable of direct contact transmission to other cats. These studies confirm that cats are susceptible to productive SARS-CoV-2 infection, but are unlikely to develop clinical disease. Further, we document that cats develop a robust neutralizing antibody response that prevented re-infection to a second viral challenge. Conversely, we found that dogs do not shed virus following infection, but do mount an anti-viral neutralizing antibody response. There is currently no evidence that cats or dogs play a significant role in human exposure; however, reverse zoonosis is possible if infected owners expose their domestic pets during acute infection. Resistance to re-exposure holds promise that a vaccine strategy may protect cats, and by extension humans, to disease susceptibility.