The coronavirus disease 19 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has resulted in unprecedented challenges to healthcare worldwide. In particular, the anthroponotic transmission of human coronaviruses has become a common concern among pet owners. Here, we experimentally inoculated beagle dogs with SARS-CoV-2 or Middle East respiratory syndrome (MERS)-CoV to compare the viral susceptibility and pathogenicity. The dogs exhibited weight loss and increased body temperature and shed the viruses in nasal secretion, faeces, and urine. Mild interstitial pneumonia lesions were observed in the lung tissues of infected dogs. Additionally, clinical characteristics of SARS-CoV-2 infection, such as increased lactate dehydrogenase levels was observed in the current study.

Salmonella is an intracellular pathogen with a cellular infection mechanism similar to that of Brucella, making it a suitable choice for use in an anti-Brucella immune boost system. This study explores the efficacy of a Salmonella Typhimurium delivery-based combination vaccine for four heterologous Brucella antigens (Brucella lumazine synthase, proline racemase subunit A, outer-membrane protein 19, and Cu/Zn superoxide dismutase) targeting brucellosis in goats. We inoculated the attenuated Salmonella delivery-based vaccine combination subcutaneously at two different inoculation levels; 5 × 109 colony-forming unit (CFU)/mL (Group B) and 5 × 1010 CFU/mL (Group C) and challenged the inoculations with virulent Brucella abortus at 6 weeks post-immunization. Serum immunoglobulin G titers against individual antigens in Salmonella immunized goats (Group C) were significantly higher than those of the non-immunized goats (Group A) at 3 and 6 weeks after vaccination. Upon antigenic stimulation, interferon-γ from peripheral blood mononuclear cells was significantly elevated in Groups B and C compared to that in Group A. The immunized goats had a significantly higher level of protection as demonstrated by the low bacterial loads in most tissues from the goats challenged with B. abortus. Relative real-time polymerase chain reaction results revealed that the expression of Brucella antigens was lower in spleen, kidney, and lung of immunized goats than of non-immunized animals. Also, treatment with our combination vaccine ameliorated histopathological lesions induced by the Brucella infection. Overall, the Salmonella Typhimurium delivery-based combination vaccine was effective in delivering immunogenic Brucella proteins, making it potentially useful in protecting livestock from brucellosis.

Background Attenuated Salmonella strain can be used as a vector to transport immunogens to the host antigen-binding sites. Objectives The study aimed to determine the protective efficacy of attenuated Salmonella strain expressing highly conserved Brucella immunogens in goats. Methods Goats were vaccinated with Salmonella vector expressing individually lipoprotein outer-membrane protein 19 (Omp19), Brucella lumazine synthase (BLS), proline racemase subunit A (PrpA), Cu/Zn superoxide dismutase (SOD) at 5 × 10 9 CFU/mL and challenge of all groups was done at 6 weeks after vaccination. Results Among these vaccines inoculated at 5 × 10 9 CFU/mL in 1 mL, Omp19 or SOD showed significantly higher serum immunoglobulin G titers at (2, 4, and 6) weeks post-vaccination, compared to the vector control. Interferon-γ production in response to individual antigens was significantly higher in SOD, Omp19, PrpA, and BLS individual groups, compared to that in the vector control (all p < 0.05). Brucella colonization rate at 8 weeks post-challenge showed that most vaccine-treated groups exhibited significantly increased protection by demonstrating reduced numbers of Brucella in tissues collected from vaccinated groups. Real-time polymerase chain reaction revealed that Brucella antigen expression levels were reduced in the spleen, kidney, and parotid lymph node of vaccinated goats, compared to the non-vaccinated goats. Besides, treatment with vaccine expressing individual antigens ameliorated brucellosis-related histopathological lesions. Conclusions These results delineated that BLS, Omp19, PrpA, and SOD proteins achieved a definite level of protection, indicating that Salmonella Typhimurium successfully delivered Brucella antigens, and that individual vaccines could differentially elicit an antigen-specific immune response.

The coronavirus disease 19 (COVID-19) pandemic, caused by the severe acute respiratory syndrome, coronavirus 2 (SARS-CoV-2), has resulted in unprecedented challenges to healthcare worldwide. In particular, the anthroponotic transmission of human coronaviruses has become a common concern among pet owners. Here, we experimentally inoculated beagle dogs with SARS-CoV-2 or Middle East respiratory syndrome (MERS-CoV) to compare their susceptibility to and the pathogenicity of these viruses. The dogs in this study exhibited weight loss and increased body temperatures and shed the viruses in their nasal secretions, feces, and urine. Pathologic changes were observed in the lungs of the dogs inoculated with SARS-CoV-2 or MERS-CoV. Additionally, clinical characteristics of SARS-CoV-2, such as increased lactate dehydrogenase levels, were identified in the current study.