中文摘要：

目的：研究IL-2对肺炎支原体（Mycoplasma pneumoniae,Mp）P1C核酸疫苗经肌注免疫BALB/c小鼠后的免疫应答水平和免疫保护作用。方法：将P1C-IL-2核酸疫苗肌注免疫BALB/c鼠,ELISA检测疫苗免疫后56天小鼠血清IgG和IgG亚类、支气管灌洗液中SIgA、IFN-γ和IL-4的水平;用2×107 Mp菌落形成单位鼻饲感染BALB/c鼠,建立感染小鼠模型,病理切片检测Mp感染后小鼠肺部炎症病理改变;将系列10倍稀释的支气管灌洗液接种于SP4固体平板,并进行菌落计数。结果：P1C-IL-2核酸疫苗免疫组小鼠血清中的总IgG、IgG1、IgG2a、IFN-γ和IL-4水平均较P1C单基因疫苗组显著增高（P〈0.05）,但两组支气管灌洗液中SIgA差异无显著性（P〉0.05）。Mp感染后第1、3、6天P1C-IL-2双基因疫苗组小鼠肺组织病理评分（HPS）较P1C单基因疫苗免疫组显著增高,但支气管灌洗液中的Mp菌落数明显减少;第9天后两组HPS和Mp菌落数差异无显著性。结论：IL-2能显著增强P1C疫苗肌注的免疫保护作用和免疫应答水平,但同时在Mp感染早期激发了较重的肺组织炎症。

英文摘要：

Objective： To investigate the immune responses and immune protection of a Mycoplasma pneumoniae （ M. pneumoni- ae） P1C DNA vaccine fused with interleukin 2 gene by intramuscular immunization. Methods： BALB/c mice were immunized by in- tramuscular inoculation of PBS, control DNAs, PIC DNA vaccine, or P1C-IL-2 fusion DNA vaccine. Levels of the anti-Pl C protein serum IgG, IgG isotypes, BAL fluids IgA, IFN-γ and IL-4 were detected by ELISA. The mice were challenged intranasally with 2×10^7 CFU M. pneumoniae strain （M129） , and the histopathologic score （HPS） were obtained in a blind fashion. Serial 10-fold dilutions of BAL fluids were immediately cultured on SP4 agar plates, quantification was performed by counting colonies on plated specimens. Results： Serum total IgG, IgG! and IgG2a isotypes and levels of IFN-γand IL-4 in P1C-IL-2 fusion DNA vaccine immunized mice were increased significantly than those in P1C DNA vaccine immunized mice （ P 〈 0.05 ）, while there was no significant differences in BAL fluids IgA between these two immune groups （ P 〉 0.05 ）. The lung tissues inflammation was aggravated and the HPS of P1C-IL- 2 DNA vaccines immunized mice were significantly increased than those in P1C DNA immunized mice on day 1 to 6 after challenged with M. pneumoniae（ P 〈0. 05 ）, and the P1C-IL-2 fusion DNA vaccine conferred significantly better protection than P1C DNA vaccine characterized by lower detectable number of M. pneumoniae strains in BAL fluids. On day 9 to 12, the HPS and the number of M. pneu- moniae strains were no significant differences between these two groups （ P 〉 0.05 ）. Conclusion： The PIC-IL-2 fusion DNA vaccine can increase systemic immune responses and protective effects against M. pneumoniae infection, but mice pre-immunized with P1C-IL- 2 DNA vaccine can develop a severe histopathological change as early as 1 to 6 days.