Abstracts Category : Other

Moving towards an improved experimental model for reproduction of pneumonia induced by Mycoplasma hyopneumoniae

by Morante Beatriz Garca

The infection with Mycoplasma hyopneumoniae is widespread in almost all pig producing countries. Despite its importance, there are still relevant points to be resolved; some of them concern the complex pathogenesis of the infection as well as the resultant pneumonia outcome. For instance, M. hyopneumoniae experimental models are a good starting point for addressing some of these unresolved matters, although wide inconsistencies are seen in reproducibility, prevalence and severity of pneumonia. Among others, the latter is a major concern in the case of veterinary medicine product efficacy compliance, especially in vaccinology, where a significant reduction in the lung lesion score is required compared to non-vaccinated pigs. Thus, a validated M. hyopneumoniae experimental model enhancing severe pneumonia reproduction is of interest. Therefore, the present thesis was raised to provide insights into this matter through the identification and optimization of experimental conditions playing a role in pneumonia outcome. Furthermore, evaluation of ante-mortem parameters that would serve to foresee such outcome was also addressed. The first study aimed to identify determinants for the successful reproduction of pneumonia under experimental conditions. To reach this goal, a systematic review of the literature followed by a multivariable statistical analysis, named recursive partitioning, was done. The results obtained constitute the first insight into those conditions supporting pneumonia development under experimental settings. M. hyopneumoniae experimental models pursuing reproduction of severe pneumonia should assess lung lesions within a study period of 8 weeks and include inoculation of M. hyopneumoniae-free pigs older than 3.5 weeks of age and co-infected with another swine respiratory pathogen. Besides, other two experimental conditions were further investigated individually into the following chapters. In the second study, pneumonia outcome consequence of M. hyopneumoniae inoculation by means of three inoculation routes (endotracheal, intranasal and aerosol) was compared. As a result, the endotracheal was the most optimal route of inoculation to induce severe pneumonia within a period of 4 weeks after inoculation. On the other side, in the third study, the growth in culture of M. hyopneumoniae strains differing in pathogenicity was daily followed by different techniques, which were evaluated as putative titration methodologies. Results obtained proved that real-time culture titration assays can be used to describe the in vitro growth of M. hyopneumoniae and to standardise M. hyopneumoniae culture protocols in the laboratory as well as inoculum production for experimental applications. The last study evaluated different humoral immune response parameters, both at local and systemic levels, as ante-mortem predictors of occurrence and severity of lung lesions associated with M. hyopneumoniae. Such an evaluation was done either in experimentally and naturally infected pigs. Overall, results indicated that humoralAdvisors/Committee Members: [emailprotected] (authoremail), true (authoremailshow), Sibila Vidal, Marina (director), Segals Coma, Joaquim (director), true (authorsendemail).