Abstract：
Infectious bovine keratoconjunctivitis (IBK) is an ocular disease that affects bovines and has significant economic and health effects worldwide. Gram negative bacteria Moraxella bovis and Moraxella bovoculi are its main etiological agents. Antimicrobial therapy against IBK is often difficult in beef and dairy herds and, although vaccines are commercially available, their efficacy is variable and dependent on local strains. The aim of this study was to analyze for the first time the genomes of Uruguayan clinical isolates of M. bovis and M. bovoculi. The genomes were de novo assembled and annotated; the genetic basis of fimbrial synthesis was analyzed and virulence factors were identified. A 94% coverage in the reference genomes of both species, and more than 80% similarity to the reference genomes were observed. The mechanism of fimbrial phase variation in M. bovis was detected, and the tfpQ orientation of these genes confirmed, in an inversion region of approximately 2.18kb. No phase variation was determined in the fimbrial gene of M. bovoculi. When virulence factors were compared between strains, it was observed that fimbrial genes have 36.2% sequence similarity. In contrast, the TonB-dependent lactoferrin/transferrin receptor exhibited the highest percentage of amino acid similarity (97.7%) between strains, followed by cytotoxins MbxA/MbvA and the ferric uptake regulator. The role of these virulence factors in the pathogenesis of IBK and their potential as vaccine components should be explored.
摘要：
传染性牛角膜结膜炎（IBK）是一种影响牛的眼部疾病，在全球范围内具有显着的经济和健康影响。革兰阴性菌牛莫拉菌和博沃菌是其主要病原。针对IBK的抗菌治疗在牛群和奶牛群中通常很困难，尽管疫苗是商业上可获得的，它们的功效是可变的，取决于局部菌株。本研究的目的是首次分析乌拉圭临床分离的牛分枝杆菌和牛分枝杆菌的基因组。从头组装并注释基因组；分析了菌毛合成的遗传基础并鉴定了毒力因子。这两个物种的参考基因组覆盖率为94%，与参考基因组的相似性超过80%。检测到牛分枝杆菌菌丝相变异的机制，这些基因的tfpQ方向得到证实，在大约2.18kb的反转区域中在博沃氏杆菌的菌毛基因中未确定相位变异。当毒力因子在菌株之间进行比较时，观察到菌毛基因具有36.2%的序列相似性。相比之下,TonB依赖性乳铁蛋白/转铁蛋白受体在菌株之间表现出最高的氨基酸相似性百分比(97.7%)，其次是细胞毒素MbxA/MbvA和铁摄取调节剂。应探索这些毒力因子在IBK发病机理中的作用及其作为疫苗成分的潜力。
