Abstract: Mannheimia haemolytica is a commensal of cattle, sheep and other ruminants, but it can also cause bovine and ovine pneumonic Pasteurellosis (infecting the respiratory tract), which is responsible for considerable economic losses in cattle and sheep industries. M. haemolytica shows different antigens. Each one of these antigens could also contribute to the development of disease and induce a specific immune response by the host. Gram negative bacteria contain outer membrane vesicles that are secreted into the medium under certain growth conditions. These vesicles retain outer membrane and cell wall constitutive components such as proteins, Lipo-Polysaccharides (LPS), muramic acid, capsule, fimbria and others. These components play a crucial role in the development of the illness as well as in the immune response activation. Antigens of immunological interest could be inside of the small Microvesicles (MVs) released by M. haemolytica under stress conditions. The immunogenicity of these MVs could stimulate an adequate humoral response, in the defense of individuals exposed to virulent strains and prevent animals from developing pathological signs. The importance of obtaining an effective immunogen lays in the prevention and control of pneumonic ovine Pasteurellosis. The objective of this study was to obtain and characterize antigens from Microvesicles (MVs) of Mannheimia haemolytica A1 and A2 serotypes, grown under stress conditions using gentamycin during logarithmic growth. In this study 2 strains of M. haemolytica were used: Strain ATCC A1 and the second strain was the A2 serotype obtained from a pneumonic lung. Characterization of M. haemolytica MVs allows recognition of the main bacterial antigens in these structures, which makes them candidates for immunological evaluation in animal models.
Cynthia Gonzalez-Ruiz , Victor Tenorio-Gutierrez , Francisco Trigo-Tavera , Magda Reyes-Lopez , Nidia Leon-Sicairos , Delfino Godinez-Vargas and Mireya de la Garza-Amaya , 2007. Characterization of Microvesicles of Mannheimia haemolytica Serotype A1 (Reference Strain) and Serotype A2 (Field Isolate) . Journal of Animal and Veterinary Advances, 6: 1172-1182.