关键词: 结核, 疫苗, 结核菌苗, 卡介苗, T淋巴细胞, 免疫, 细胞

Abstract: Background　Tuberculosis（TB） is a global chronic infectious disease with the highest mortality caused by an infective agent.But there is a lack of safe and effective vaccines to prevent adult tuberculosis.Vaccination mainly uses body's immune memory to prevent the re-invasion of pathogens.Therefore，studying the immune memory and proliferation capacity of T cells is crucial for the development of new tuberculosis vaccines.Objective　To investigate the effects of a new tuberculosis vaccine strain（B/R strain） on T cell immune memory and proliferation capacity.Methods　In January 2019，48 SPF female C57BL/6 mice aged 6-8 weeks were randomly divided into PBS group，BCG group，H37Ra group and B/R strain group，with 12 mice in each group，and were subcutaneously inoculated，respectively.At 8，12，and 16 weeks after immunization，the splenic lymphocytes of three mice in each group were extracted and cultured in vitro，and the levels of central memory lymphocytes（TCM） and effector memory lymphocytes（TEM） were detected by flow cytometry.ELISA was used to detect antigen-specific Th1/Th2 cytokines（IL-2，IFN-γ and IL-4） levels secreted by splenic lymphocytes.CFSE labeling method was used to detect the proliferation of CD4+ and CD8+ T lymphocytes.Results　At 8，12，and 16 weeks after immunization，the TCM and TEM levels of CD4+ in BCG，H37Ra，and B/R strain groups were higher than those of PBS group（P<0.05）.At 8 weeks post-inoculation，the level of CD4+ TEM in B/R group was lower than that in H37Ra group（P<0.05）.At 16 weeks post-inoculation，B/R strain group showed higher level of TCM of CD4+ than H37Ra and BCG groups（P<0.05），and higher level of TEM of CD4+ than BCG group（P<0.05）.At 8，12，and 16 weeks after immunization，the TCM and TEM levels of CD8+ in BCG，H37Ra，and B/R strain groups were higher than those of PBS group（P<0.05）.At 12 weeks post-inoculation，the level of TEM of CD8+ in B/R strain group was higher than that in H37Ra and BCG groups（P<0.05）.At 16 weeks post-inoculation，the TCM and TEM levels of CD8+ in B/R strain group were higher than those of BCG group（P<0.05）.At 8，12，and 16 weeks post-inoculation，IL-2 and IFN-γ levels in PBS group were lower than those of other three groups（P<0.05）.At 12 weeks post-inoculation，the level of IFN-γ in B/R strain group was higher than that of BCG group（P<0.05）.At 16 weeks post-inoculation，IFN-γ and IL-2 levels in B/R strain group were higher than those of BCG and H37Ra groups（P<0.05）.The proliferation rates of CD4+ and CD8+ T lymphocytes in BCG，H37Ra and B/R strain groups were higher than those of PBS group（P<0.05）.The proliferation rates of CD4+ and CD8+ T lymphocytes in B/R strain group were higher than those of BCG and H37Ra groups（P<0.05）.Conclusion　The immunizing with the B/R strain in mice could awake up the body to produce higher levels of protective immune memory cells，mainly Th1 type immune responses，and enhance the proliferation capacity of T cells.

Key words: Tuberculosis；Vaccines；Tuberculosis vaccines；BCG Vaccine；T-Lymphocytes；Immunity, cellular