Mannheimia haemolytica and the pathogenesis of enzootic bronchopneumonia

摘要: Mannheimia (M.) haemolytica (formerly Pasteurella [P.] haemolytica) is the primary aetiological agent of pneumonic pasteurellosis--one most important respiratory diseases in cattle and sheep. While bovine pasteurellosis regarded to be mainly caused by M. serotype A1, Germany during last years also A6, sheep can infected all serotypes although there an increased prevalence A2 A5-7. The obligate pathogenicity proven isolation pure cultures from lungs as well infection studies. Knowledge about virulence mechanisms their molecular basis are fragmentary, probably due complex gene regulation associated factors lung tissues. This review summarizes current literature covering substantiate a model pathogenesis. After A1 strains have colonized upper tract they replace other unknown date. fulminant proliferation microorganisms colonize lower tract, finally entering alveolar spaces. An inflammatory cascade initiated LPS Leukotoxin, causing activation complement system release cytokines. Pathognomonic for strong influx neutrophiles accompanied accumulation fibrin, necrosis Depending on lesion size this fibronecrotizing pneumonia result death animals. In addition, possible protective antigens discussed. There still great effort development efficacious vaccines against various worldwide. scarce knowledge concerning presence distribution role pathogenesis made it difficult determine suitable vaccine candidate past. lack variability individual isolates. Genome sequence analysis haemolytica, enabling proteomics transciptomics, hopefully will give new insight into pasteurellosis.