First isolation of Brucella canis from pet dogs in Sichuan Province, China: Molecular characterization, pathogenicity and antigen location analysis

Abstract

Brucellosis is a worldwide zoonosis that is primarily caused by Brucella melitensis, Brucella abortus, Brucella suis, and Brucella canis. However, in China, information regarding brucellosis in pet dogs caused by B. canis is limited. In the present study, we conducted a comprehensive molecular, pathological, and immunohistochemical analysis to detect this pathogen in pet dogs. Molecular methods, combining three types of PCR assays, identified two strains isolated from two pet dogs as Brucella canis. Histopathological changes revealed extensive inflammation and necrosis in the liver, lung, spleen, kidney, testicle, and lymph nodes, among which changes in the spleen were the most serious. Immunohistochemistry results demonstrated the detection of B. canis antigens in the lesions of all examined tissues. Strong positive staining was primarily found in the spleen, liver, and testicle. In conclusion, this study was the first to report the isolation of two B. canis strains from pet dogs in Sichuan province, southwestern China, and to further evaluate B. canis antigen location in tissues. Our study will contribute to the understanding of B. canis pathogenicity in naturally-infected pet dogs.