Objective To investigate the immunological properties of Rv1009 domain. Methods BALB/c mice were immunized with Rv1009 domain three times at 2-week interval. ELISA was used to detect the antiRv1009 domain antibody titer in the sera of immunized mice sera. The spleen lymphocytes of the immunized mice were separated and the stimulation index (SI) was measured by MTT colorimetry. Levels of secreted IFN-γ, IL-10 and IL-12 upon specific antigen stimulation were detected by ELISA. The BALB/c mice immunized with Rv1009 domain were intravenously infected with MTB H37Rv. Four weeks after the final injection, the number of CFU in spleens was determined. Results The titer of the specific antibody in sera of the immunized BALB/c mice was 1:12 800. The SI of Rv1009 domain immunized group (2. 40±0. 18) was significantly higher than that of saline immunized group (0.90±0.21). The IFN-γ,IL-10 and IL-12 levels in culture supematant of spleen lymphecytes from the fusion proteins immunized mice was (1 432±30) ng/L, (503±11) ng/L and (311±11) ng/L respectively, significant different from that of saline immunized group[(256±20) ng/L, (76±6) ng/L and(56±8) ng/L,P<0.01]. Four weeks after the final injection,compared with normal saline immunized mice (6.64±0.13), dramatic reduction in MTB replication was observed in the spleen (4.86±0.14) from BALB/c mice immunized with fusion proteins following a subsequent MTB H37Rv challenge, but the protection efficacy of mice immunized with Rv1009 domain was not as good as that of BCG vaccination group (3.81±0.16). Conclusion Rv1009 domain can be used as a candidate for the new TB vaccine.

Objective To purify Micrococcus luteus Rpf and Rpf domain fusion protein, and to in-vestigate its effects on growth of Mycobacterium tuberculosis. Methods The recombinant plasmids pPro-EXHT-Rpf and pPro-EXHT-Rpf domain were expressed in E. Coli DHSa and then purified under denaturing condition via Ni-NTA purification system and confirmed by Western blot. The biochemical property of the M. Luteus Rpf and Rpf domain was analyzed by stimulating the resuscitation of M. Tuberculosis H37Ra which were in non-culturable' condition. Results The Rpf and Rpf domain products achieved 95% and 93% pure respectively, and the molecular weight was 30 x 103 and 12 x 103, the yield of purification was about 471 mg/L and 337 mg/L of the culture. The M. Luteus Rpf and Rpf domain from the E. Coli showed activity of stimulating the resuscitation of M. Luteus and M. Tuberculosis H37Ra in non-cuhurable' condition which could be inhibited by monoclonal antibodies of M. Luteus Rpf domain remarkably. Conclusion It was dem-onstrated that the purification of Rpf and Rpf domain have high biological activity for further functional, pharmacological and clinical investigations, and M. Luteus Rpf domain protein is fully active as M. Lateus full-length Rpf.

To prepare a lipid nanoparticle (LNP)-based subunit vaccine of Mycobacterium tuberculosis (Mtb) antigen EsxV and study its immunological characteristics, the LNP containing EsxV and c-di-AMP (EsxV: C: L) was prepared by thin film dispersion method, and its encapsulation rate, LNP morphology, particle size, surface charge and polyphase dispersion index were measured. BALB/c mice were immunized with EsxV: C: L by nasal drops. The levels of serum and mucosal antibodies, transcription and secretion of cytokines in lung and spleen, and the proportion of T cell subsets were detected after immunization. EsxV: C: L LNPs were obtained with uniform size and they were spherical and negatively charged. Compared with EsxV: C immunization, EsxV: C: L mucosal inoculation induced increased sIgA level in respiratory tract mucosa. Levels of IL-2 secreted from spleen and ratios of memory T cells and tissue-resident T cells in mice were also elevated. In conclusion, EsxV: C: L could induce stronger mucosal immunity and memory T cell immune responses, which may provide better protection against Mtb infection.
Animals ; Mice ; Mycobacterium tuberculosis ; Antigens, Bacterial ; Immunization ; Nanoparticles ; Vaccines, Subunit ; Mice, Inbred BALB C