【摘要】 用5株猪肺炎霉形体分别人工感染乳兔,仅济南株适应于乳兔。经过长期继代,培育出1株毒力显著减弱并保持良好免疫原性的兔化弱毒株。该株对乳兔的最佳接种部位是胸腔,最小感染量为0.5×10^-5克,在乳兔体内存活14天左右,在成兔体内可产生血凝抗体,其最小感染量为2×10^-5至2×10^-6克。扫描电镜观察表明,兔化弱毒株在乳兔支气管内繁殖,纤毛未见明显损伤。该株对猪的潜伏期的几何平均值为27.9天,对支气管纤毛损伤轻微,不发生同居感染,不影响增重,保护率为70-80%,免疫期6个月以上,最小免疫剂量为5×10^-2克,气管、胸腔、滴鼻、气溶胶接种均可产生免疫力。用免化弱毒株作种子制造大兔冻干苗15批,先后在北京、广东、福建、浙江、江西、湖南、宁夏、河北等8个省（市）自治区的30个猪场,接种20个不同品种、不同年龄的10363头猪,证明安全有效。兔化弱毒株的培养成功,为今后开展猜喘气病的预防工作创造了有利条件。更多还原

【Abstract】 Five strains of Mycoplasma hyopneumonia were experimently used for infecting suckling rabbits. The Z-strain of them was gradually attenuated through continuous passages in rabbits and finally became a lapinized strain with protective immunogenicity in pigs. The characteristics of the lapinized strain in rabbits were as follows. The optimal injection location was thoracic carity and the minimal infectious dose in suckling rabbits was 0.5 ×10^-5 g of infected lung tissue; The organisms could live in the tissue of rabbits approximately for 14 days and induce specific antibody responses in adult rabbits following injection of a minimal immune dose, 2×10⁵-2×10^-6g. The infected suckling rabbits did not show any clinical signs or death. The results of SEM observation demonstrated that the strain propagated in the bronchi of inoculated rabbits, but the cilia seemed to be normal. The mean value of the incubation periods of the lapinized strain in pigs was 27.9 days. This strain did not cause confluent pneumonia in pigs. Contact infection did not occur between inoculated pigs and uninoculated animals. It had no effect on weight gain of vaccinated pigs. 70-80% pigs were protected when they were experimently challenged with a pathogenic strain （Z-strain） of Mycoplasma hyopneumonia. A more than six month duration of immunity was detected. The minimal dose for producing immunity in pigs was 5×10²g of infected tissue. Various administration routes including intratracheal, intrapleural and intranasal could induce immunity in Fifteen batches of lyophilized vaccines consisting of infected adult rabbit lungs were prepared by using the lapinized strain as seeds. In field trials, 10 363 pigs of different breeds and ages from more than 30 pig farms in 8 Provinces, Municipal Cities and Autonomous Regions were inoculated with the vaccines. The results indicated that the lapinized strain was of safety and efficacy in MPS naturally occurring herds. The suc- cess in developing the lapinized strain provided seeds for production of the vaccines against MPS, and therefore an effective method for controlling the disease in pig farmas更多还原