São Paulo State University (Unesp), School of Agricultural and Veterinarian Sciences, Jaboticabal, SP, Brazil.
Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Vet Microbiol. 2020 May;244:108647. doi: 10.1016/j.vetmic.2020.108647. Epub 2020 Mar 24.
This study aimed to assess immunopathological factors and M. hyopneumoniae (M. hyo) load in macroscopic lesion formation at four timepoints after experimental infection of swine. To do this, 24 M. hyo-free pigs were divided into two groups: non-inoculated control (n = 8) and inoculated (n = 16). At day 0 post-infection (dpi), animals of infected group were intratracheally inoculated with 5 mL of lung inoculum containing 10 CCU (Color Changing Units) ∕mL of M. hyo strain 232, while control group was mock infected with 5 mL of sterilized Friis medium. At 14, 28, 42 and 56 dpi, four animals from the infected group and two from the control group were euthanized and necropsied. The extent of macroscopic lung lobe lesions was visually assessed, scored and lesion samples (qPCR, histopathology and gene expression) were collected. The macroscopic lesion score and estimated M. hyo load (in copies/μL) at the different timepoints were: 14 dpi: 18.5 %-1.55 × 10 copies∕μL; 28dpi: 15.8 %-8.4 × 10 copies∕μL; 42 dpi: 7.0 %-3.2 × 10 copies∕μL and 56 dpi: 6.3 %-1.11 × 10 copies∕μL; Significant and positive correlations between macroscopic lung lesion and the pathogen load were found (coefficient range: 0.77-0.99). The cytokine's IL-6 (0.73) and INF-γ (-0.69) gene expression were significantly (p < 0.05) correlated to macroscopic lung lesion score while IL-8, TNF- α, IL-1α and IL-1β were associated to other pathological effects such as losses in average daily weight gain and microscopic lesion score. The results provide a better understanding about the pathogenicity of M. hyo strain 232 and the host-pathogen interactions, which may be helpful for the development of new treatments or control measures.
本研究旨在评估实验感染猪后四个时间点的免疫病理学因素和支原体（M. hyopneumoniae，M. hyo）负荷与宏观病变形成的关系。为此，将 24 头无支原体感染的猪分为两组：未接种对照组（n = 8）和接种组（n = 16）。在感染后 0 天（day 0 post-infection，dpi），感染组动物经气管内接种含有 10 CCU（Color Changing Units）/mL M. hyo 株 232 的肺接种物 5 mL，而对照组则用 5 mL 无菌 Friis 培养基进行模拟感染。在 14、28、42 和 56 dpi，每组分别处死 4 头感染动物和 2 头对照动物，进行剖检。肉眼评估肺叶宏观病变的严重程度并评分，收集病变样本（qPCR、组织病理学和基因表达）。不同时间点的宏观病变评分和估计的 M. hyo 负荷（以拷贝/μL 计）为：14 dpi：18.5%-1.55×10 拷贝/μL；28dpi：15.8%-8.4×10 拷贝/μL；42 dpi：7.0%-3.2×10 拷贝/μL；56 dpi：6.3%-1.11×10 拷贝/μL；在宏观肺病变与病原体负荷之间发现了显著的正相关关系（相关系数范围：0.77-0.99）。细胞因子 IL-6（0.73）和 INF-γ（-0.69）的基因表达与宏观肺病变评分显著相关（p < 0.05），而 IL-8、TNF-α、IL-1α 和 IL-1β与平均日增重和微观病变评分的其他病理效应相关。结果提供了对 M. hyo 株 232 的致病性和宿主-病原体相互作用的更好理解，这可能有助于开发新的治疗或控制措施。
