Expression of NRAMP1 and iNOS in Mycobacterium avium subsp. paratuberculosis naturally infected cattle

Paratuberculosis (PTB) is a chronic disease caused by M. avium subsp. paratuberculosis (MAP) that affects several animal species, and some studies have suggested that there may be a relationship between Crohn's disease and PTB. Significant aspects of PTB pathogenesis are not yet completely understood, such as the role of macrophages. Natural resistance-associated macrophage protein 1 (NRAMP1) and the inducible nitric oxide synthase (iNOS) molecules have shown nonspecific effects against several intracellular pathogens residing within macrophages. However, these molecules have been scarcely studied during natural infection with MAP. In this work, changes in NRAMP1 and iNOS expression were surveyed by immunohistochemistry in tissue samples from MAP-infected cattle and healthy controls. Our findings show strong specific immunolabeling against both NRAMP1 and iNOS molecules, throughout granulomatous PTB-compatible lesions in ileum and ileocaecal lymph nodes from paratuberculous cattle compared with uninfected controls, suggesting a relationship between the expression of these molecules and the pathogenesis of PTB disease.

Efficacy of florphenicol premix in weanling pigs experimentally infected with Actinobacillus pleuropneumoniae

The efficacy of a florfenicol premix was studied in weaning pigs experimentally inoculated with Actinobacillus pleuropneumoniae. Twenty five clinically healthy pigs were distributed into 3 groups; group A non-medicated, groups B and C orally medicated with 20 and 40 ppm of florfenicol respectively. The pigs were fed during 12 consecutive days and on day 5 all the groups were challenged with A. pleuropneumoniae serotype 1. All the animals in Group A developed clinical signs. Most of the pigs in the medicated groups maintained a good health status. Postmortem examination revealed severe pleuropneumonia in pigs from the control group and pneumonic lesions in 40% of the animals treated with 20 ppm of florfenicol. Development of pleuropneumonia was prevented in all the pigs medicated with 40 ppm of florfenicol. Actinobacillus pleuropneumoniae was recovered from the lungs of all control animals and from one pig of each of the medicated groups, however, the avidin biotin peroxidase (ABC-P) method detected the presence of the microorganism in all the animals. We demonstrated that medication with feed containing 40 ppm of florfenicol blocked efficiently the signs and lesions caused by A. pleuropneumoniae and increased the daily body weight gain.