Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA.
Anim Health Res Rev. 2009 Dec;10(2):141-3. doi: 10.1017/S1466252309990181.
Bovine respiratory disease (BRD) involves complex interactions amongst viral and bacterial pathogens that can lead to intense pulmonary inflammation (fibrinous pleuropneumonia). Viral infection greatly increases the susceptibility of cattle to secondary infection of the lung with bacterial pathogens like Mannheimia haemolytica and Histophilus somni. The underlying reason for this viral/bacterial synergism, and the manner in which cattle respond to the virulence strategies of the bacterial pathogens, is incompletely understood. Bovine herpesvirus type 1 (BHV-1) infection of bronchial epithelial cells in vitro enhances the binding of M. haemolytica and triggers release of inflammatory mediators that attract and enhance binding of neutrophils. An exotoxin (leukotoxin) released from M. haemolytica further stimulates release of inflammatory mediators and causes leukocyte death. Cattle infected with H. somni frequently display vasculitis. Exposure of bovine endothelial cells to H. somnii or its lipooligosaccharide (LOS) increases endothelium permeability, and makes the surface of the endothelial cells pro-coagulant. These processes are amplified in the presence of platelets. The above findings demonstrate that bovine respiratory pathogens (BHV-1, M. haemolytica and H. somni) interact with leukocytes and other cells (epithelial and endothelial cells) leading to the inflammation that characterizes BRD.
牛呼吸道疾病（BRD）涉及病毒和细菌病原体之间的复杂相互作用，可导致剧烈的肺部炎症（纤维素性化脓性肺炎）。病毒感染极大地增加了牛对曼海姆氏菌和副流感嗜血杆菌等细菌性病原体继发感染的易感性。这种病毒/细菌协同作用的根本原因，以及牛对细菌病原体毒力策略的反应方式，尚未完全了解。牛疱疹病毒 1 型（BHV-1）在体外感染支气管上皮细胞可增强与曼海姆氏菌的结合，并触发炎症介质的释放，吸引并增强中性粒细胞的结合。从曼海姆氏菌释放的外毒素（白细胞毒素）进一步刺激炎症介质的释放并导致白细胞死亡。感染副流感嗜血杆菌的牛常表现为血管炎。牛内皮细胞暴露于副流感嗜血杆菌或其脂寡糖（LOS）会增加内皮细胞的通透性，并使内皮细胞具有促凝性。在血小板存在的情况下，这些过程会被放大。上述发现表明，牛呼吸道病原体（BHV-1、曼海姆氏菌和副流感嗜血杆菌）与白细胞和其他细胞（上皮细胞和内皮细胞）相互作用，导致 BRD 特征性的炎症。
