Development And Application Of The PCR Targeting System In Actinobacillus Pleuropneumoniae & Serologic Detection Of Actinobacillus Pleuropneumoniae In Swine By OmlA Enzyme-Linked Immunosorbent Assay

Porcine contagious pleuropneumonia (PCP) caused by Actinobacillus pleuropnermoniae (APP) is a severe, contagious pulmonary disease of pigs that cause important economic losses in industrialized pigs production worldwide.Immunization is the main method to prevent and control this disease. The current commercial vaccines are still primarity killed whole cell bacterins and subunit vaccines, which generally reduce mortality from APP infection but frequently fail to prevent serever morbidity and economic loss due to the chronic effects of the disease on growth rate and feed efficiency.In contrast, natural and experimental infection can induce protection against any heterologous serotype. Thus, live attenuated vaccines might be a viable approach to solve this problem. The methods described previously for the construction of mutant strains of A. pleuropneuminiae have some disadvantage.This respiratory disease can be acute, extensive, and respiratory hemorrhagic or chronic, localized and associated with pleuritis. The first observations of this disease was made by Pattison et al. (1957), now occurs in most pig-keeping countries. For example, mutagenesis using a chemical or a transposon mediated approaches present a random approach and allow for the selection of mutants with a distinct phenotype only; muttions not resulting in a distinct phenotype can not be constructed by these means. All these mutants, which is achieved by systems allowing targeted mutagenesis by homologous recombination, however, carry a permanent antibiotic resistance marker and, therefore, are not suitable as vaccine strains. Immunization is the major method to prevent and control of the disease, the commercial vaccines to prevent PCP in China is bacterin vaccine.The bacterin vaccine can only reduce the mortality, not morbidity and chronic infection against same serotype, little cross-protection against heterologous challenge. Therefore, the development of more safer and more effective vaccine against porcine pleuropneumonia has been required to prevent the disease and diminish the economic losses efficiently. From the study to the virulence factor of the APP, the exotoxins (Apx toxins) secreted by APP were proved to play an important role in the pathogenesis of porcine pleuropneumonia and were important protective antigens either, the vaccine with exotoxins toxoid improved protection markedly. The study includes: 1. The isolation of XT0404 and the animal regression trial...