VISAVET Health Surveillance Centre, Universidad Complutense de Madrid, Madrid, Spain.
Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Madrid, Spain.
BMC Vet Res. 2021 Apr 7;17(1):148. doi: 10.1186/s12917-021-02848-3.
Although the pathogenic effect of members of the Mycobacterium tuberculosis complex in susceptible hosts is well known, differences in clinical signs and pathological findings observed in infected animals have been reported, likely due to a combination of host and pathogen-related factors. Here, we investigated whether Mycobacterium bovis strains belonging to different spoligotypes were associated with a higher risk of occurrence of visible/more severe lesions in target organs (lungs and/or lymph nodes) from infected animals. A large collection of 8889 samples belonging to cattle were classified depending on the presence/absence of tuberculosis-like lesions and its degree of severity. All samples were subjected to culture irrespective of the presence of lesions, and isolates retrieved were identified and subjected to spoligotyping. The association between the presence/severity of the lesions and the isolation of strains from a given spoligotype was assessed using non-parametric tests and Bayesian mixed multivariable logistic regression models that accounted for origin (region and herd) effects.
Results suggested a difference in severity in lesioned samples depending on the strain's spoligotype. An association between specific spoligotypes and presence of lesions was observed, with a higher risk of finding lesions in animals infected with strains with spoligotypes SB0120, SB0295 and SB1142 compared with SB0121, and in those coming from certain regions in Spain.
Our results suggest that strains belonging to certain spoligotypes may be associated with a higher probability in the occurrence of gross/macroscopic lesions in infected cattle, although these observational findings should be confirmed in further studies that allow accounting for the effect of other possible confounders not considered here, and ultimately through experimental studies.
虽然结核分枝杆菌复合群成员在易感宿主中的致病作用已为人所知，但在感染动物中观察到的临床症状和病理发现存在差异，这可能是由于宿主和病原体相关因素的综合作用。在这里，我们研究了不同 spoligotype 的牛分枝杆菌菌株是否与受感染动物的靶器官（肺和/或淋巴结）中可见/更严重病变的发生风险增加有关。根据是否存在类似结核病的病变及其严重程度，对属于牛的 8889 个大样本进行了分类。所有样本均进行了培养，无论是否存在病变，均回收分离物并进行 spoligotyping。使用非参数检验和贝叶斯混合多变量逻辑回归模型评估病变的存在/严重程度与从特定 spoligotype 分离菌株之间的关联，该模型考虑了起源（地区和畜群）的影响。
结果表明，病变样本的严重程度取决于菌株的 spoligotype。观察到特定 spoligotype 与病变的存在之间存在关联，与 SB0121 相比，感染 SB0120、SB0295 和 SB1142 spoligotype 菌株的动物中发现病变的风险更高，并且来自西班牙某些地区的动物中发现病变的风险更高。
我们的结果表明，某些 spoligotype 的菌株可能与受感染牛中大体/宏观病变的发生概率更高相关，尽管这些观察结果需要在进一步的研究中得到证实，这些研究允许考虑这里未考虑的其他可能混杂因素的影响，并最终通过实验研究。
