SARS-CoV-2 Prevalence and Variant Surveillance among Cats in Pittsburgh, Pennsylvania, USA.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infects many mammals, and SARS-CoV-2 circulation in nonhuman animals may increase the risk of novel variant emergence. Cats are highly susceptible to SARS-CoV-2 infection, and there were cases of virus transmission between cats and humans. The objective of this study was to assess the prevalence of SARS-CoV-2 variant infection of cats in an urban setting. We investigated the prevalence of SARS-CoV-2 variant infections in domestic and community cats in the city of Pittsburgh (n = 272). While no cats tested positive for SARS-CoV-2 viral RNA, 35 cats (12.86%) tested SARS-CoV-2-antibody-positive. Further, we compared a cat-specific experimental lateral flow assay (eLFA) and species-agnostic surrogate virus neutralization assay (sVNT) for SARS-CoV-2 antibody detection in cats (n = 71). The eLFA demonstrated 100% specificity compared to sVNT. The eLFA also showed 100% sensitivity for sera with >90% inhibition and 63.63% sensitivity for sera with 40-89% inhibition in sVNT. Using a variant-specific pseudovirus neutralization assay (pVNT) and antigen cartography, we found the presence of antibodies to pre-Omicron and Omicron SARS-CoV-2 variants. Hence, this approach proves valuable in identifying cat exposure to different SARS-CoV-2 variants. Our results highlight the continued exposure of cats to SARS-CoV-2 and warrant coordinated surveillance efforts.

Effect of age, dose and antibiotic therapy on the development of Clostridium difficile infection in neonatal piglets.

Piglet diarrhea is associated with increased pre-weaning mortality, poor growth rates, and variation in weight at weaning. Clostridium difficile is a known cause of enteric disease in neonatal piglets, yet risk factors associated with C. difficile infection in piglets are unknown. The objectives of this study were (1) to evaluate the consistency and severity of lesions in piglets challenged with C. difficile at different bacterial doses (DOSAGE experiment), (2) evaluate the use of antibiotics as a contributing risk factor in 1-day-old piglets (ANTIMICROBIAL experiment), and (3) to provide a clinical and histological evaluation of C. difficile infection in 10-day-old piglets (AGE experiment). One hundred and eleven conventional neonatal pigs were snatch farrowed and divided into experimental groups addressing the objectives. In the DOSAGE experiment, 40 1-day-old piglets were sham inoculated or challenged with varying amounts of C. difficile heat shocked spores and euthanized 72 h post infection. Results indicate a clear trend for disease development as bacterial numbers increase. In the ANTIMICROBIAL experiment, 39 1-day-old piglets were challenged and then treated with one of four different antibiotics after 16 h. No significant difference in disease development was found. Thirty-three 10-day-old piglets were given varying doses of C. difficile in the AGE experiment. Disease and lesions were reproduced in 10-day-old piglets. Combined results indicate that C. difficile dosage appears to be an important factor that influences the appearance and severity of lesions, 10-day-old pigs can develop disease associated with C. difficile, and antibiotic administration following inoculation may not be a major contributor for disease in neonatal piglets.