Department of Veterinary Pathobiology, Texas A&M University, College of Veterinary Medicine, College Station, TX, United States of America.
Department of Veterinary Pathology & Poultry Diseases, College of Veterinary Medicine, University of Baghdad, Baghdad, Iraq.
PLoS One. 2019 Jun 20;14(6):e0218809. doi: 10.1371/journal.pone.0218809. eCollection 2019.
Canine brucellosis, caused by Brucella canis, is a disease of dogs and represents a public health concern as it can be transmitted to humans. Canine brucellosis is on the rise in the United States and there is currently no vaccine for use in dogs. Mice have been extensively utilized to investigate host-pathogen interactions and vaccine candidates for smooth Brucella species and could serve a similar role for studying B. canis. However, comparatively little is known about B. canis infection in mice. The objective of this study was to characterize the kinetics of colonization and pathogenicity of B. canis in mice in order to evaluate the mouse as a model for studying this pathogen. C57BL/6 mice were inoculated intraperitoneally with 105, 107, or 109 CFU of Brucella canis RM6/66 and euthanized 1-, 2-, 4-, 6-, 9-, and 12-weeks post-inoculation. B. canis induced splenomegaly in mice infected with 109 CFU at 1- and 2 weeks post-inoculation while no gross lesions were observed in other dose groups. Infection at the two higher doses resulted in dose-dependent granulomatous hepatitis and histiocytic infiltration of the spleen and mesenteric lymph nodes by 1-2 weeks. B. canis was cultured from the liver, spleen, uterus, bone marrow, lung, and kidney in all groups with colonization declining at a slow but steady rate throughout the experiment. Clearance was achieved by 9 weeks 105 CFU group and by 12 weeks in the 107 CFU group, while B. canis persisted in the spleen until 12 weeks in the highest dose group. Although B. canis does not demonstrate significant replication in C57BL/6 mice, it has the ability to establish an infection, induce splenomegaly, and persist for several weeks in multiple organs. Moreover, 1 x 107 CFU appears to be a suitable challenge dose for investigating vaccine safety.
犬布鲁氏菌病由犬布鲁氏菌引起，是一种犬类疾病，由于可能传染给人类，因此引起了公共卫生关注。犬布鲁氏菌病在美国呈上升趋势，目前尚无犬用疫苗。小鼠已被广泛用于研究光滑布鲁氏菌属的宿主-病原体相互作用和疫苗候选物，也可以在研究犬布鲁氏菌时发挥类似作用。然而，人们对犬布鲁氏菌感染小鼠的了解相对较少。本研究的目的是描述犬布鲁氏菌在小鼠体内的定殖和致病性动力学，以评估小鼠作为研究该病原体的模型。将 C57BL/6 小鼠经腹腔接种 105、107 或 109 CFU 的犬布鲁氏菌 RM6/66，分别在接种后 1、2、4、6、9 和 12 周安乐死。109 CFU 感染的小鼠在接种后 1 和 2 周出现脾肿大，而其他剂量组未观察到明显的大体病变。在两个较高剂量下，感染导致剂量依赖性的化脓性肝炎和脾和肠系膜淋巴结的组织细胞浸润，在 1-2 周时发生。在所有组中，均从肝、脾、子宫、骨髓、肺和肾中培养出犬布鲁氏菌，整个实验期间，定植率呈缓慢但稳定的下降趋势。105 CFU 组在 9 周时清除，107 CFU 组在 12 周时清除，而在最高剂量组中，犬布鲁氏菌在脾中持续存在至 12 周。虽然犬布鲁氏菌在 C57BL/6 小鼠中没有表现出明显的复制能力，但它有能力建立感染，引起脾肿大，并在多个器官中持续存在数周。此外，1×107 CFU 似乎是研究疫苗安全性的合适挑战剂量。
