Natural SARS-CoV-2 infection in two cats in Spain

Abstract

Purpose: SARS-CoV-2 is a zoonotic pathogen able to infect humans, pets and other animal species, mustelids and felids being highly susceptible. Experimentally, it has been shown that SARS-CoV-2 replicates efficiently in cats, inducing humoral immunity and causing a variable clinical presentation. Here we report the case of two cats (G1 and G2) naturally infected with SARS-CoV-2 after contact with their COVID-19 positive owner diagnosed in September 2020. Methods & Materials: Oral swabs soaked in PBS were collected daily from 1 to 16 days after the owner tested positive for SARS-CoV-2. Urine and feces were taken several times during this period. Samples were analyzed by in-house real-time RT-PCR (based on CDC 2019-nCoV_N1). Serum samples, collected at day 30, were tested by IDVet multi-species ELISA. Vero E6 cells was used for virus isolation. Partial spike gene was sequenced by Sanger and compared with the owner sequence and the reference Wuhan 2019 (NC_045512.2). Results: G1 showed apathy, anorexia, lack of grooming and mild respiratory symptoms (tearing and sneezing) for 5 days and then recovered gradually. G2 remained clinically asymptomatic. Viral RNA peak in oral swabs was detected in both cats at day 2 showing similar Ct value (25). SARS-CoV-2 was consistently shedding in G1 for 9 days, after sporadically detected until day 16. Viral shedding in G2 decreased quickly during the first 6 days. Faeces were positive to SARS-CoV-2 until 9 (G1) or 12 (G2) days post-viral detection. Viral RNA in urine was sporadically detected in G2 with high Ct values. Specific antibodies were detected in both cats one month after infection. Virus isolation was not successful. Cats and owner sequences of the spike protein were homologous with two mutations (A222V and D614G) that classify the virus within the 20A.EU1 clade. Conclusion: SARS-CoV-2 natural infection of two cats occurred after close contact with their infected owner. Both cats developed humoral immune response but they showed different clinical presentation and viral shedding pattern. Oral swabs and feces are proper samples for SARS-CoV-2 detection in cats. Variant 20A.EU1 detected in this study emerged in early summer 2020, presumably in Spain, and subsequently spread throughout Europe.