Serological screening of SARS-CoV-2 infection in companion animals of Buenos Aires suburbs

The Coronavirus Disease 2019 (COVID-19) is a zoonotic disease caused by the pandemic virus SARS-CoV-2. Domestic and wild animals are susceptible to infection and are potential reservoirs for virus variants. To date, there is no information about the exposure of companion animals in Buenos Aires Suburbs, the area with the largest population in Argentina where the highest number of COVID-19 human cases occurred during the first infection wave. Here we developed a multi-species indirect ELISA to measure antibodies reactive to the SARS-CoV-2 receptor-binding domain (RBD) from several vertebrates constituting the class Mammalia, making it a valuable tool for field serosurveillance. The ELISA cut-off value was estimated by sera from dogs, cats, cattle, and pigs sampled before 2019 (n = 170), considering a 98% percentile and a grey zone to completely exclude any false positive result. Specificity was confirmed by measuring levels of neutralizing antibodies against canine coronavirus, the avidity of specific antibodies, and their capacity to impede the binding of a recombinant RBD protein to VERO cells in an In-Cell ELISA. Sera from 464 cats and dogs sampled in 2020 and 2021 ("pandemic" samples) were assessed using the RBD-ELISA. Information on COVID-19 disease in the household and the animals' lifestyles was collected. In Buenos Aires Suburbs cats were infected at a higher proportion than dogs, seroprevalence was 7.1 and 1.68%, respectively. Confirmed COVID-19 in the caregivers and outdoor lifestyle were statistically associated with seropositivity in cats. The risk of cats getting infected living indoors in COVID-19-negative households was null. The susceptibility of mammals to SARS-CoV-2, the possibility of transmission between animals themselves and humans, together with the free-roaming lifestyle typical of Buenos Aires suburban companion animals, urge pursuing responsible animal care and avoiding human interaction with animals during the disease course. The multi-species RBD-ELISA we developed can be used as a tool for serosurveillance of SARS-CoV-2 infection in mammalians (domestic and wild), guiding further targeted virological analyses to encounter susceptible species, interspecies transmission, and potential virus reservoirs in our region.

Proteomic analysis of proteins released by Tritrichomonas foetus: Identification of potential targets for the development of new diagnostic methods

Bovine trichomonosis (BT), a disease of the bovine urogenital tract, is caused by the protozoan Tritrichomonas foetus (Tf). Tf causes endometritis, infertility, and premature death of the embryo, which generates considerable economic losses. The proteins released can mediate fundamental interactions between the pathogen and the host, triggering factors associated with the symptomatology, immune evasion and pathogenesis characteristic of the species. However, little is known about the profile of the proteins released by Tf. In order to contribute to their knowledge, we performed an isolation protocol and a proteomic profiling of the supernatant (SN) content of six Tf isolates. A total of 662 proteins present in the SN of Tf were detected, out of which 121 were shared by the six isolates, while the remaining 541 were found in at least one of the isolates studied. The comparative analyses using the databases of Tf strain genome K revealed 32.9% of uncharacterized proteins. The bioinformatic analyses showed that the main molecular functions predicted were binding (47.9%) and catalytic activity (38.2%). Additionally, we performed immunodetection assays to evidence the antigenic potential of SN proteins. Interestingly, we observed great ability to detect SN proteins from all six isolates using serum from immunized mice and infected bulls. A complementary mass spectrometry assay allowed us to determine that the proteins that showed the strongest signal intensity in the immunoassays were Grp78 (A0A1J4IZS3) and Ap65 (A0A1J4JSR1). This work represents the first proteomic characterization of Tf SN proteins and their antigenic potential, which might be interesting for the future design of new diagnosis and treatment methods for BT.

Serological evidence of SARS-CoV-2 infection in pets naturally exposed during the COVID-19 outbreak in Argentina

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), has rapidly spread worldwide. The monitoring of animals has shown that certain species may be susceptible to be infected with the virus. The present study aimed to evaluate the presence of SARS-CoV-2 antibodies by ELISA and virus neutralization (VN) in pets from owners previously confirmed as COVID-19-positive in Argentina. Serum samples of 38 pets (seven cats and 31 dogs) were obtained for SARS-CoV-2 antibody detection. Three out of the seven cats and 14 out of the 31 dogs were positive for SARS-CoV-2 by ELISA, and one cat and six dogs showed the presence of neutralizing antibodies in which the cat and two of the six dogs showed high titers. Another dog from which three serum samples had been obtained within eight months from the diagnosis of its owner showed the presence of antibodies at different times by both ELISA and VN. However, the results showed that the antibodies decreased slightly from the first to the third sample. Our results provide evidence that SARS-CoV-2 infection in pets living with COVID-19-positive humans from Argentina during the outbreak of SARS-CoV-2 can be detected by serology assay.

First detection and molecular analysis of SARS-CoV-2 from a naturally infected cat from Argentina

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent of coronavirus disease 2019 (COVID-19), has rapidly spread worldwide. Studies of transmission of the virus carried out in animals have suggested that certain animals may be susceptible to infection with SARS-CoV-2. The aim of the present study was to investigate the infection of SARS-CoV-2 in pets (18 cats and 20 dogs) from owners previously confirmed as COVID-19-positive. Oropharyngeal and rectal swabs were taken and analyzed by real-time RT-PCR assays, while blood samples were taken for antibody detection. Of the total pets analyzed, one cat was found reactive to SARS-CoV-2 by real-time RT-PCR of an oropharyngeal and a rectal swab. This cat presented only sneezing as a clinical sign. Serological analysis confirmed the presence of antibodies in the serum sample from this cat, as well as in the serum from another cat non-reactive to real-time RT-PCR. Complete sequence and phylogenetic analysis allowed determining that the SARS-CoV-2 genome belonged to the B.1.499 lineage. This lineage has been reported in different provinces of Argentina, mainly in the Metropolitan Area of Buenos Aires. This study notifies the first detection of the natural infection and molecular analysis of SARS-CoV-2 in a cat from Argentina whose owner where COVID-19-positive. Although there is currently no evidence that cats can spread COVID-19, results suggest that health authorities should test pets with COVID-19-positive owners.