猪支原体肺炎活疫苗（168株）气溶胶免疫后呼吸道sIgA分泌及抗原存留规律

KINETICS OF SIGA SECRETION AND BACTERIN PROLIFERATION IN RESPIRATORY TRACTS AFTER AEROSOL VACCINATION OF ATTENUATED MYCOPLASMA HYOPNEUMONIAE VACCINE(168 STRAIN)

猪支原体肺炎是由猪肺炎支原体(Mycoplasma hyopneumoniae ,Mhp)引起的猪的一种慢性呼吸道疾病,严重影响养猪业发展,活疫苗气溶胶免疫是防治该病的新措施。为研究猪肺炎支原体活疫苗(168株)经气溶胶免疫后,疫苗株在免疫猪肺内的占位存留规律,选用3周龄不吃初乳猪27头,随机分为3组,G1气溶胶免疫组12头,G2肺内免疫组12头,同时设立阴性对照3头。分别于免疫后第2 h、7 d、14 d及28 d进行鼻拭子Mhp sIgA检测以及血清抗体检测。另外在上述时间点分别宰杀G1和G2组各3头,对照组在实验组免疫后第28 d宰杀,采集肺泡灌洗液,分别进行Mhp sIgA检测及Mhp疫苗株含量检测。结果显示:(1)所有试验猪至实验结束,Mhp血清抗体未出现转阳现象;(2)鼻拭子sIgA水平G1组在免疫后第14 d与对照组相比上升,差异具有显著统计学意义(p <0.05);G2组在免疫后第7 d和14 d与相应的对照组相比上升,差异具有显著统计学意义(p <0.05),各时间点G1组与G2组sIgA水平差异不具备统计学意义(p >0.05);(3)G1组肺泡灌洗液中的 sIgA在免疫后14 d部分转阳(阳性率33.33%),28 d全部转阳(阳性率100%);G2组在免疫14 d时已全部转阳(阳性率100%),各时间点G1组与G2组sIgA水平差异不具备统计学意义(p >0.05);(4)气溶胶免疫组肺泡灌洗液内Mhp疫苗株浓度在免疫后第2 h、7 d、14 d和28 d分别是相应肺内免疫组的0.37倍、1.01倍、0.88倍以及0.52倍。猪支原体肺炎活疫苗(168株)经气溶胶免疫后,和肺内免疫一样可以诱导免疫猪的局部黏膜免疫以及具有同等的占位效应,且经气溶胶免疫的疫苗株在免疫仔猪体内的增殖水平可能与其诱导的黏膜免疫水平相关。

Enzootic pneumonia (EP) is a chronic respiratory disease of swine caused by Mycoplasma hyopneumoniae (Mhp),leading to significant economic losses to the pig industry globally.Aerosol vaccination is a new strategy for the prevention of the disease.In this study,we examined the retention rules of the attenuated Mhp vaccine (168 strain) in swine lungs after aerosol immunization.Total 27 snatch-farrowed,colostrum-deprived (SF-pCD) pigs at 3 weeks old were randomly divided into three groups.There were 12 pigs in both group 1 and group 2 and 3 pigs in control group.Pigs in group 1 were vaccinated with attenuated Mhp vaccine (168 strain) via aerosol.Pigs in group 2 were vaccinated via intrapulmonary injection.Nasal swabs and serum samples were collected for detecting sIgA and serum antibodies at 2 h,7,14 and 28 d post vaccination.At the same time,3 pigs in group 1 and group 2 were euthanized to collect bronchoalveolar lavage fluids (BALFs) for detecting sIgA and live Mhp.There were 4 important findings:(1) Serum antibodies were not detected in all 3 groups during the whole experiment.(2) As compared to the control group,sIgA level in nasal swabs of group 1 on 14 dpi,and group 2 on 7 and 14 dpi increased significantly (p <0.05).However,there was no obvious difference (p >0.05) in sIgA levels between group 1 and group 2.(3) The positive rate of sIgA in BALFs of group 1 was 33.33% and 100% on 14 and 28 dpi,respectively.In group 2,the positive rate of sIgA in BALFs was 100% for both 14 and 28 dpi.However,there was no significant difference (p >0.05) between group 1 and group 2 at these points.(4) Ratios of live Mhp vaccine titers in BALFs in group 1/group 2 were 0.37 at 2 h,1.01 on 7 d,0.88 on 14 d and 0.52 on 28 d post vaccination.In conclusion,both aerosol and intrapulmonary vaccinations induced mucosal immunity and had equivalent vaccine occupancy effect in immunized pigs.The replication/survival of live Mhp vaccine in lungs was possibly related to mucosal immunity level.