Comparison of diagnostic performances of different serological tests for SARS-CoV-2 antibody detection in cats and dogs

SARS-CoV-2 exposure in hunting and stray dogs of southern Italy

Evidence of exposure to the pandemic SARS-CoV-2 has been described in numerous animal species, including pets, which are predisposed to coming into contact with this virus due to their close relationship with owners. It has been accepted that dogs are poorly susceptible to this virus and that seroconversion, rather than shedding, occurs following infection, which can occur directly through contact with infected owners or indirectly through environmental contamination. In this study, the seroprevalence of SARS-CoV-2 was evaluated in apparently health hunting and stray dogs of Campania region, southern Italy (sampled in September 2023). A total of 5/112 (4.5%) animals tested seropositive using two different commercial ELISAs. Stray animals had greater exposure than hunting dogs. The feces and blood of each animal were tested with a real-time PCR targeting the nucleocapsid and ORF1ab coding sequences. No animal tested positive in molecular investigations, indicating a past exposure without active infection at the time of sampling.

Domestic and wild animal samples and diagnostic testing for SARS-CoV-2

From the first cases in 2019, COVID-19 infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have resulted in over 6 million human deaths in a worldwide pandemic. SARS-CoV-2 is commonly spread from human to human through close contact and is capable of infecting both humans and animals. Worldwide, there have been over 675 animal outbreaks reported that resulted in over 2000 animal infections including domestic and wild animals. As the role of animal infections in the transmission, pathogenesis, and evolution of SARS-CoV-2 is still unfolding, accurate and reliable animal diagnostic tests are critical to aid in managing both human and animal health. This review highlights key animal samples and the three main diagnostic approaches used for animal testing: PCR, serology, and Next Generation Sequencing. Diagnostic results help inform (often difficult) clinical decision-making, but also possible ways to mitigate spread among pets, food supplies, or wildlife. A One Health approach has been key to monitoring the SARS-CoV-2 pandemic, as consistent human-animal interactions can lead to novel variants. Having multiple animal diagnostic tests for SARS-CoV-2 available is critical to ensure human, animal, and environmental health.

Serosurveillance of SARS-CoV-2 in companion animals in Sarawak, Malaysia

SARS-CoV-2 is a zoonotic betacoronavirus that was first reported at the dawn of 2019 in Wuhan, China and has since spread globally, causing an ongoing pandemic. Anthroponotic transmission was reported early, with confirmed infections reported in 26 species to date, including dogs and cats. However, there is a paucity of reports on the transmission of SARS-CoV-2 to companion animals, and thus, we aimed to estimate the seroprevalence of SARS-CoV-2 in dogs and cats in Sarawak, Malaysia. From August 2022 to 2023, we screened plasma samples of 172 companion animals in Sarawak, Malaysia, using a species-independent surrogate virus neutralization test. Our findings revealed the presence of neutralizing antibodies of SARS-CoV-2 in 24.5% (27/110) of dogs and 24.2% (15/62) of cats. To the best of our knowledge, this is the first report of the seroprevalence of SARS-CoV-2 in companion animals in Malaysia. Our findings emphasize the need for pet owners to distance themselves from their pets when unwell, and a strategy must be in place to monitor SARS-CoV-2 in companion animals to assess the potential impact of the virus on companion animals.

SARS-CoV-2 and animals, a long story that doesn't have to end now: What we need to learn from the emergence of the Omicron variant

OIE, the world organization for animal health, recently released an update on the state of the art of knowledge regarding SARS-CoV-2 in animals. For farmed animals, ferrets and minks were found to be highly susceptible to the virus and develop symptomatic disease both in natural conditions and in experimental infections. Lagomorphs of the species Oryctolagus cuniculus are indicated as highly susceptible to the virus under experimental conditions, but show no symptoms of the disease and do not transmit the virus between conspecifics, unlike raccoon dogs (Nyctereutes procyonoides), which in addition to being highly susceptible to the virus under experimental conditions, can also transmit the virus between conspecifics. Among felines, the circulation of the virus has reached a level of cases such as sometimes suggests the experimental use of vaccines for human use or treatments with monoclonal antibodies. But even among wild animals, several species (White-tailed deer, Egyptian rousettes, and minks) have now been described as potential natural reservoirs of the virus. This proven circulation of SARS-CoV-2 among animals has not been accompanied by the development of an adequate surveillance system that allows following the evolution of the virus among its natural hosts. This will be all the more relevant as the surveillance system in humans inevitably drops and we move to surveillance by sentinels similar to the human flu virus. The lesson that we can draw from the emergence of Omicron and, more than likely, its animal origin must not be lost, and in this mini-review, we explain why.

Do Blood Phenotypes of Feline AB Blood Group System Affect the SARS-CoV-2 Antibody Serostatus in Cats?

Cats are susceptible to coronavirus infections, including infection by human severe acute respiratory syndrome coronavirus (SARS-CoV). In human ABO system blood groups, alloantibodies can play a direct role in resistance to infectious diseases. Individuals with the AB blood type were over-represented in the SARS-CoV-2 infection group. Blood type AB individuals lack both anti-A and anti-B antibodies, and therefore lack the protective effect against SARS-CoV-2 infection given by these antibodies. Starting from this knowledge, this pilot preliminary study evaluated a possible association between feline blood phenotypes A, B, and AB and serostatus for SARS-CoV-2 antibodies in cats. We also investigated selected risk or protective factors associated with seropositivity for this coronavirus. A feline population of 215 cats was analysed for AB group system blood phenotypes and antibodies against the nucleocapsid (N-protein) SARS-CoV-2 antigen using a double antigen ELISA. SARS-CoV-2 seropositive samples were confirmed using a surrogate virus neutralization test (sVNT). Origin (stray colony/shelter/owned cat), breed (DSH/non DSH), gender (male/female), reproductive status (neutered/intact), age class (kitten/young adult/mature adult/senior), retroviruses status (seropositive/seronegative), and blood phenotype (A, B, and AB) were evaluated as protective or risk factors for SARS-CoV-2 seropositivity. Seropositivity for antibodies against the SARS-CoV-2 N-protein was recorded in eight cats, but only four of these tested positive with sVNT. Of these four SARS-CoV-2 seropositive cats, three were blood phenotype A and one was phenotype AB. Young adult age (1-6 years), FeLV seropositivity and blood type AB were significantly associated with SARS-CoV-2 seropositivity according to a univariate analysis, but only blood type AB (p = 0.0344, OR = 15.4, 95%CI: 1.22-194.39) and FeLV seropositivity (p = 0.0444, OR = 13.2, 95%CI: 1.06-163.63) were significant associated risk factors according to a logistic regression. Blood phenotype AB might be associated with seropositivity for SARS-CoV-2 antibodies. This could be due, as in people, to the protective effect of naturally occurring alloantibodies to blood type antigens which are lacking in type AB cats. The results of this pilot study should be considered very preliminary, and we suggest the need for further research to assess this potential relationship.