| Enzootic Pneumonia, the respiratory disease caused by M. hyopneumoniae is one of the most prevalent ones in the swine industry worldwide, affecting pigs of all ages and all types on swine farm or in swine production systems. Mycoplasma is also considered to play a central role in Porcine Respiratory Disease Complex (PRDC) with other pathogen. Vaccination is one of the effective methods for mycoplasma prevention and control. To date, inactivated and attenuated mycoplasma hyopneumoniae vaccine are the two main vaccines against M. hyopneumomiae. Compared with the inactivated vaccine, attenuated mycoplasma hyopneumoniae vaccine has more advantages, for its efficacy are not affected by maternal antibody and wild mycoplasma hyopneumoniae infection. In order to explore the protective immunity of Mycoplasma hyopneumoniae vaccine, attenuated mycoplasma hyopneumoniae 168 strain vaccine was selected as the subject of this study, the research compared the immune efficacy and evaluated the clinical effect of immune. Based on this, a mycoplasma hyopneumoniae eradication program with vaccine immunity at its core was designed and the Mycoplasma hyopneumoniae was succefully eradicated in a pig farm. The main contents of the study are as follows:Content 1:Comparison of the immune efficacy on Mhp vaccines. This research carried out an experiment on the immune efficacy, three kinds of commercial vaccines against Mhp were selected. They are intrapulmonary live vaccine, intranasal attenuated live vaccine and intramuscular killed vaccine. The results showed that the group immunized with intrapulmonary live vaccine had the highest sIgA level at day 7 post immunization, furthermore, the antibody remained at a high level for at least 42 days post immunization. Meanwhile, the protective rate of intrapulmonary vaccine was 100%. From the point of daily weight gain, the three pigs in intrapulmonary vaccine group gained 2.4kg,2.7kg and 3.8kg respectively at day 28 post Mhp challenge, which was the highest compared with other two groups. Conclusion:Among the three vaccines, intrapulmonary attenuated live vaccine Mhp (168) is the best one for Mph cleaning-up in pig farms.Content 2:Evaluation of the clinical immunization effect of attenuated live vaccine Mhp (168) strain. Piglets at 5-7 days from three farms at different sizes without Mhp vaccination were selected for Mhp (168) strain immunization. The vaccine efficacy was evaluated by important index including mortality rate, morbidity of fattening pigs between 13 and 18 weeks, the average of cough index and lung lesion of slaughter pig. Results:The mortality rate from the three farms had decreased 1.8%,7.3% and 14.2% respectively. In addition, the morbidity of Mph at half or one year post immunization of fattening pigs between 13 to 18 weeks decreased significantly. The average of cough index of fattening pigs between 13 and 18 weeks had decreased remarkablely at both excited and quiet status. And the lung lesion of slaughter pigs was under 10%. Conclusion:The Mhp live vaccine (168 strain) has a good protective immunity.Content 3:Technology application and effect assessment of the eradication of mycoplasma hyopneumoniae. In this study 430 back-up sows from a new pig farm was selected to undertake an eradication programme based on attenuated mycoplasma hyopneumoniae 168 strain vaccine immunization in piglets, supplemented by closed herd, drug control, the Swiss method and so on. Through clinical symptoms observation, the average cough index, serology, SIgA and pathogen monitoring (every three month, a total of 9 months), the eradication efficacy was evaluated. Results:No clinical symptoms of mycoplasma pneumonia of swine was observed within 9 months of eradication programme, the average cough index of sows and fattening pig were all 0. Serological monitoring showed that the positive rate of mycoplasma hyopneumoniae antibody in sows decreased gradually, all Ab became negative 9 months later. The same trend was observed in fattening pig at the age of 21 and 60 days, at the age of 120 days, the antibody remained negative. The OD of SIgA was between 0.4 and 0.5 at the age of day 21. There was no difference of the OD of SIgA in the pig at the age of 60 days compared with 21 days of age when the programe was implemented three months, however there was significantly higher SIgA level when the programe was implemented six months and nine months compared with 21 days (p<0.01).In the first three month, the OD of SIgA of 120 days of age pigs was significantly higher than that of 21 and 60 days of age. Pathogen monitoring showed that the nasal swab positive rate of sows decreased gradually, and nine months later, all the swab was negative. the positive rate of finishing pigs remained 10%-40%. Used PCR (P380 primers) to differential diagnosis of Mycoplasma were found in live vaccine, and not the wild strains of mycoplasma. Conclusion: Taken the Mhp living vaccine(168) as the core of the Mhp cleaning-up program, the Mycoplasma hyopneumoniae was succefully eradicated in a pig farm.To sum up, the purpose of the research is to explore the technology on cleaning-up Mhp in domestic swine farms, and provide a theoretical basis and practical experience of eradication for the future research. In this study, three experiments were conducted, the following conclusions were drawn:1. Comparison of the immune efficacy of different pig mycoplasma pneumonia vaccines proved that the attenuated mycoplasma hyopneumoniae 168 strain vaccine has a better protective immunity.2. The Mhp vaccine (168 strains) field experiment showed that the vaccine could significantly drop the incidence of swine enzootic pneumonia in clinical application.3. By using the Mhp cleaning-up program developed by the research with the Mhp living vaccine(168) as its core, the Mycoplasma hyopneumoniae was succefully eradicated in a pig farm. |
PDF Full Text Request