摘要
Mycoplasma ovipneumoniae (M. ovipneumoniae) is a respiratory pathogen associated with mild to moderate respiratory disease in domestic lambs and severe pneumonia outbreaks in wild ruminants such as bighorn sheep. However, whether M. ovipneumoniae by itself causes clinical respiratory disease in domestic sheep in the absence of secondary bacterial pathogens is still unclear. The goal of our study was to better understand the role of M. ovipneumoniae as a respiratory pathogen in domestic sheep and to explore potential antibiotic treatment approaches. Therefore, we inoculated four 4-month-old, specific-pathogen-free lambs with fresh nasal wash fluids from M. ovipneumoniae-infected sheep. The lambs were monitored for M. ovipneumoniae colonization, M. ovipneumoniae-specific antibodies, clinical signs, and cellular and molecular correlates of lung inflammation for eight weeks. All lambs then were treated with gamithromycin and observed for an additional four weeks. M. ovipneumoniae inoculation resulted in stable colonization of the upper respiratory tract in all M. ovipneumoniae-inoculated, but in none of the four mock-infected control lambs. All M. ovipneumoniae-infected lambs developed a robust antibody response to M. ovipneumoniae within 2 weeks. However, we did not observe significant signs of respiratory disease, evidence of lung damage or inflammation in any of the infected lambs. Interestingly, treatment with gamithromycin, which blocked growth of the M. ovipneumoniae in vitro, failed to reduce M. ovipneumoniae colonization. These observations indicate that, in the absence of co-infections, M. ovipneumoniae caused asymptomatic colonization of the upper respiratory tract that was resistant to clearance by the host immune response and by gamithromycin treatment.
摘要译文
支原体Ovipneumoniae（M.Ovipneumoniae）是一种呼吸病原体，其在国内羊羔和野生反刍动物如大角羊等狂热的肺炎疫情中有呼吸道病原体。然而，在没有继发性细菌病原体的情况下，M. Ovipneumoniae是否本身导致家用绵羊的临床呼吸道疾病仍然不清楚。我们研究的目标是更好地了解M. Ovipneumoniae作为国内绵羊的呼吸道病原体的作用，并探索潜在的抗生素治疗方法。因此，我们接种了来自M. Ovipneumoniae感染绵羊的新鲜鼻腔洗液的四个4个月大的特定病原体的羊羔。监测羔羊的M.Ovipneumoniae殖民化，M.Ovipneumoniae特异性抗体，临床症状和细胞和分子相关的肺炎八周。然后将所有羔羊用Gamithromycin治疗并额外观察四周。 M. Ovipneumoniae接种导致所有M. ovipneumoniae接种的上呼吸道稳定定植，但在四种模拟的对照羔羊中没有。所有M. Ovipneumoniae感染的羔羊在2周内对M. Ovipneumoniae的鲁棒抗体反应开发出鲁棒抗体反应。然而，我们没有观察到呼吸系统疾病的重大迹象，肺部损伤的证据或任何受感染的羊羔中的炎症。有趣的是，用Gabithromycin治疗，其中含有M. Ovipneumoniae的生长，未能降低绵羊的植物殖民化。这些观察结果表明，在没有共感染的情况下，M.Ovipneumoniae引起了上呼吸道的无线性定植，其抵抗宿主免疫应答和通过Gamithromycin处理。
Thea Johnson[a];Kerri Jones[a];B. Tegner Jacobson[a];Julia Schearer[a];Noah Adams[b];Isaak Thornton[c];Cassie Mosdal[a];Steven Jones[a];Mark Jutila[a];Agnieszka Rynda-Apple[a];Thomas Besser[d];Diane Bimczok[a]. Experimental infection of specific-pathogen-free domestic lambs with Mycoplasma ovipneumoniae causes asymptomatic colonization of the upper airways that is resistant to antibiotic treatment[J]. Veterinary Microbiology, 2022,265