NSW Department of Primary Industries, Elizabeth Macarthur Agricultural Institute, Woodbridge Road Menangle, NSW 2568, Australia.
Vet Microbiol. 2012 Dec 28;161(1-2):186-95. doi: 10.1016/j.vetmic.2012.07.025. Epub 2012 Jul 22.
Differences in Mycoplasma hyopneumoniae strain virulence and infection patterns will affect experimental challenge systems used to evaluate vaccine efficacy. Two strains (Hillcrest and Beaufort) were assessed by experimental pig challenge for their ability to induce clinical and pathological lesions and cytokine responses. Tracheobronchial lavage fluid (TBLF) was collected before and 17-18 days after challenge with Hillcrest (n=8), Beaufort (n=8) or no organisms (n=3). Coughing was assessed twice daily, and at slaughter 21 (n=9) or 28 (n=10) days post-challenge, gross and histopathology of lungs were quantified and a quantitative PCR (mhp183 qPCR) was applied to detect M. hyopneumoniae DNA in tissues and TBLF. Hillcrest was clearly superior to Beaufort in its ability to induce coughing and pneumonic lesions. At 17-18 days, interleukin (IL)-1β and IL-6 concentrations in TBLF were only significantly higher (8.7 and 5.1 fold respectively) than controls (P<0.001) in Hillcrest-challenged pigs. Lungs of all Hillcrest-challenged pigs were qPCR positive at either slaughter date, but only at day 28 in Beaufort-challenged pigs. M. hyopneumoniae DNA was highest in concentration in lungs 21 days after Hillcrest challenge, and was detected in the spleen, kidney and/or liver of Hillcrest-challenged pigs, but not in Beaufort pigs. While M. hyopneumoniae DNA concentration in TBLF was elevated following Hillcrest and Beaufort challenge, there was no significant difference in mean mycoplasmal DNA concentration detected in TBLF from pigs challenged with either isolate (P>0.05). Thus a suitable challenge strain, coupled with lung pathology and cytokine assays, are valuable in assessing post-challenge responses. Assessment of M. hyopneumoniae DNA in lung and abdominal tissues by mhp183 qPCR, in conjunction with histopathology, were valuable in confirming M. hyopneumoniae infection.
支原体肺炎菌株毒力和感染模式的差异将影响用于评估疫苗效力的实验性挑战系统。通过实验性猪挑战评估了两种菌株（希克里斯特和博福特）诱导临床和病理损伤以及细胞因子反应的能力。在希克里斯特（n=8）、博福特（n=8）或无生物体（n=3）攻毒前和攻毒后 17-18 天收集气管支气管灌洗液（TBLF）。每天评估两次咳嗽，在攻毒后 21 天（n=9）或 28 天（n=10）屠宰时，对肺进行大体和组织病理学量化，并应用定量 PCR（mhp183 qPCR）检测组织和 TBLF 中的支原体肺炎 DNA。希克里斯特明显优于博福特，能够诱导咳嗽和肺炎病变。在 17-18 天时，TBLF 中的白细胞介素（IL）-1β和 IL-6 浓度仅在希克里斯特攻毒猪中比对照（P<0.001）显著升高（分别为 8.7 和 5.1 倍）。在任何屠宰日期，所有希克里斯特攻毒猪的肺部均为 qPCR 阳性，但仅在博福特攻毒猪中在第 28 天为阳性。在希克里斯特攻毒后 21 天，肺部的支原体肺炎 DNA 浓度最高，在希克里斯特攻毒猪的脾脏、肾脏和/或肝脏中检测到，但在博福特猪中未检测到。虽然在希克里斯特和博福特攻毒后 TBLF 中的支原体肺炎 DNA 浓度升高，但攻毒猪的 TBLF 中支原体 DNA 平均浓度无显著差异（P>0.05）。因此，合适的攻毒菌株加上肺病理学和细胞因子检测对于评估攻毒后反应非常有价值。通过 mhp183 qPCR 结合组织病理学评估肺和腹部组织中的支原体肺炎 DNA，对于确认支原体肺炎感染非常有价值。
