Abstract：
This study was designed to characterize the dynamics of infection of Mycoplasma hyopneumoniae in naïve replacement gilts after introduction to positive systems. Ninety-eight naïve gilts were monitored in three positive commercial farms (A, B, and C). The näive gilts were housed for 21 days in pens adjacently located to older gilt cohorts (named seeders), which have been naturally exposed to the positive farms. The infection dynamics was evaluated by PCR and ELISA, from laryngeal swabs and serum samples, respectively. Samples were collected at 150 (arrival), 165, 180, 210, 240, 270, 300 days of age (doa), and pre-farrowing. Infection occurred rapidly on farms A and B, taking 25.2 and 23.9 days for 95% of gilts to be PCR positive, respectively. There was no influence on the number of seeders at the time of exposure, but their absence (farm C) could explain the extended period it took for gilts to get infected (69.4 days). On average, it took 162.2 days after the first PCR detection for 85% of gilts to stop shedding the bacterium. The serology results were consistent with the herd infection curve. At pre-farrowing, 100% of gilts seroconverted and 36.7% remained PCR positive. A total of 1.33% of piglets were positive at weaning. Fifteen variants were detected among the three farms by MLVA. The acclimation protocol was efficient and easy to perform, and the presence of seeders was likely critical for early acclimation for M. hyopneumoniae.
摘要：
这项研究旨在描述引入阳性系统后，幼稚替代后备母猪的猪肺炎支原体感染动力学。在三个积极的商业农场中监测了98只幼稚的后备母猪(A，B,andC).näive后备母猪在邻近较老的后备母猪（称为播种机）的围栏中饲养了21天，自然地暴露于积极的农场。通过PCR和ELISA评估感染动态，喉拭子和血清样本，分别。样本在150（到达）时收集，165、180、210、240、270、300日龄(doa)，分娩前。A和B农场感染迅速发生，95%的后备母猪PCR阳性需要25.2天和23.9天，分别。暴露时对播种机的数量没有影响，但是他们的缺席（农场C）可以解释后备母猪被感染的时间延长（69.4天）。平均而言,第一次PCR检测后，85%的小母猪需要162.2天才能停止脱落细菌。血清学结果与畜群感染曲线一致。在分娩前，100%的后备母猪血清转化和36.7%保持PCR阳性。共有1.33%的仔猪断奶时呈阳性。MLVA在三个农场中检测到15种变体。适应协议高效且易于执行，播种机的存在可能对猪肺炎支原体的早期适应至关重要。
