SARS-CoV-2 Serological and Biomolecular Analyses among Companion Animals in Campania Region (2020–2021)

Abstract

The first reports of SARS-CoV-2 among domestic and wild animals, together with the rapid emergence of new variants, have created serious concerns regarding a possible spillback from animal hosts, which could accelerate the evolution of new viral strains. The present study aimed to investigate the prevalence and the transmission of SARS-CoV-2 among both owned and stray pets. A total of 182 dogs and 313 cats were tested for SARS-CoV-2. Specimens collected among owned and stray pets were subjected to RT-PCR and serological examinations. No viral RNA was detected, while anti-N antibodies were observed in six animals (1.3%), one dog (0.8%) and five cats (1.7%). Animals’ background revealed that owned cats, living with owners with COVID-19, showed significantly different prevalence compared to stray ones (p = 0.0067), while no difference was found among dogs. Among the seropositive pets, three owned cats also showed moderate neutralizing antibody titers. Pets and other species are susceptible to SARS-CoV-2 infection because of the spike affinity towards their ACE2 cellular receptor. Nevertheless, the risk of retransmission remains unclear since pet-to-human transmission has never been described. Due to the virus’ high mutation rate, new reservoirs cannot be excluded; thus, it is reasonable to test pets, mostly if living in households affected by COVID-19.

Vaccination of cats with Sad23L-nCoV-S vaccine candidate against major variants of SARS-CoV-2

“…The convalescent sera of COVID-19 patients (n = 21) displayed the mean NAb titer of IC 50 29.3 to Omicron variant, which was decreased by 20.2-fold compared with the wild-type strain (IC 50 589.2). Referring NAb titers from cats infected symptomatically with SARS-CoV-2 (wild type) 29 or vaccinated with an alphavirus replicon-based vaccine, 11 although cat NAb titers against Omicron variant were reduced by 39.5-fold compared with wild-type strain in our study, but the NAb titer still remained sufficiently high at IC 50 131 (mean) in 10 weeks post-prime vaccination. However, due to biosafety restriction, the evaluation of vaccine efficacy in vaccinated cats was not conducted by challenging with live SARS-CoV-2.…”

Evidence of Exposure to SARS-CoV-2 in Dogs and Cats from Households and Animal Shelters in Korea

“…In Southern Italy, no SARS-CoV-2 viral RNAs were detected in companion animals in an investigation of 182 dogs and 313 cats. However, the VN to the virus was detected in 0.8% of dogs and 1.7% of cats tested [ 25 ]. Another study in the Netherlands detected 18.8% (17.3% of dogs and 20.4% of cats) cases of SARS-CoV-2 positivity (PCR- and/or antibody positive) out of 156 dogs and 152 cats living in households with at least one confirmed COVID-19-positive person, whereas the SARS-CoV-2 prevalence was much lower in 183 dogs and 140 cats that had simply visited a clinic (3.3% of dogs and 6.4% of cats) [ 26 ].…”

“…Since antigens or antibodies were detected in the investigated animals regardless of whether the companion family was infected, this could cause continuous viral circulation between humans and animals; a disease that Started as zoonosismay lead to reverse zoonosis [ 4 , 19 , 25 ]. This is the first report of SARS-CoV-2 infection in companion animals in Korea.…”

First serological evidence of SARS-CoV-2 natural infection in small ruminants

“…ELISA tested doubtful and positive samples were next submitted to Virus Serum Neutralization (VSN) test in BLS-3 laboratory with a standardized micro-method already described (Cardillo et al, 2022 ). Briefly, sera were first heat-inactivated at 56 °C for 30 min and 10-fold pre-dilution was performed in sterile 96-well microplates, followed by 2-fold serial dilution up to 1:10,240.…”

“…Thus, the absence or limited clinical signs may lead to underdiagnosed cases of SARS-CoV-2 infection in animal species. Furthermore, it has been demonstrated by experimental and natural infections, that positive animals show low amounts of viral shedding, during a very short time (Murphy and Ly, 2021;Ulrich et al, 2020;Falkenberg et al, 2021;Gaudreault et al 2021;Cardillo et al, 2022;Fiorito et al, 2022). Therefore, serological examinations, revealing a previous viral infection, are a useful tool to investigate SARS-CoV-2 host range and prevalence in animal species, and, in particular, virus serum neutralization assay (VSN), that is species-independent and is based on the principle of in vitro interaction between specific neutralizing antibodies and the investigated virus (Wernike et al, 2020).…”