USING LIVE GENETICALLY MODIFIED ACTINOBACILLUS PLEUROPNEUMONIAE STRAINS TO IMMUNISE AGAINST DISEASE

摘要

Actinobacillus pleuropneumoniae (App) is the etiologic agent of porcine pleuropneumoniae, which is responsible for large economic losses worldwide in the pig industry. Infection of a heard with App may be asymptomatic or may present with chronic or acute disease. Acute disease in a non-immune herd is often associated with high mortality. In contrast, chronic disease may be less obvious but still responsible for substantial losses due to poor weight gain and failure to thrive. The direct mode of transmission of App means that infection is more prevalent under intensive breeding conditions, with the introduction of asymptomatic carriers into a non-immune herd being an important cause of pleuropneumonia outbreaks. Acute disease is characterized by fibrinous adhesions in the pleural cavity and necrotic and hemorrhagic lesions in the lungs. Chronic lesions involve considerable fibrosis and purelent inflammation, while asymptomatic infections have few gross lesions other than convalescent chronic lesions.