Anti-IgG2b polyclonal antibody [Cy3]

Tuberculosis (TB) remains an enormous global health problem, and a new vaccine against TB more potent than the current inadequate vaccine, the Bacille Calmette-Guerin (BCG), is urgently needed. BCG has proven to be an effective recombinant delivery vehicle for foreign antigens because of its ability to induce long-lived specific humoral and cellular immunity. Experimental evidences have revealed that Ag85B, ESAT-6 and Rv2608 are important immunodominant antigens of Mycobacterium tuberculosis and are all promising vaccine candidate molecules. In this study, we have constructed a novel recombinant BCG (rBCG) expressing fusion protein Ag85B-ESAT6-Rv2608 and evaluated the immunogenicity of rBCG in C57BL/6 mice. Results show there is strong TB-specific CD4+ and CD8+ T lymphocytes proliferative response in mice immunized with rBCG vaccine, especially the cytotoxic CD8+ T cells playing an important role in protection against TB. And rBCG immunization has induced a significantly strong Th1 immune response, characterized by the increased ratio of IgG2b/IgG1. Results also show that rBCG immunization could increase the secretion of Th1 cytokines such as TNF-a and IL-2 and could decrease the secretion of Th2 cytokine IL-10. Moreover, it was shown that rBCG immunization induced a strong humoral response in mice, characterized by the elevated IgG titre. Therefore, we conclude that this rBCG immunization could increase both cellular immune response and antigen-specific humoral response significantly as compared to BCG immunization in mice. The above results illustrated that rBCG::Ag85B-ESAT6-Rv2608 is a potential candidate against M. tuberculosis for further study.

Elderly organisms are more susceptible to infectious diseases. However, the impact of aging on antiparasitic mechanisms, especially the nitric oxide pathway, is poorly understood. Using an integrated in vivo and in vitro model, we compared the severity of Trypanosoma cruzi infection in young and elderly (8 or 72 weeks old) mice. Forty C57BL/6 mice were randomized into four groups: Y-inf, young infected; Yn-inf, young uninfected; A-inf, aged infected; An-inf, aged uninfected. Parasitemia was measured daily, and animals were euthanized after 15 days of infection. Trypanosoma cruzi-induced inflammatory processes were analyzed in blood and heart samples, as well as in bone marrow-derived macrophages (BMDMs) co-cultured with splenocytes isolated from young or elderly mice. Our results indicated upregulated IgG2b and IL-17 production in elderly animals, which was not sufficient to reduce parasitemia, parasitic load and myocarditis to levels observed in young animals. The higher susceptibility of elderly mice to T. cruzi infection was accompanied by reduced cardiac inducible nitric oxide synthase (iNOS) gene expression, nitric oxide (NO) and IFN-gamma levels, as well as an antagonistic upregulation of arginase-1 expression and arginase activity. The same responses were observed when BMDMs co-cultured with splenocytes from elderly mice were stimulated with T. cruzi antigens. Our findings indicate that elderly mice were more susceptible to T. cruzi infection, which was potentially related to an attenuated response to antigenic stimulation, inhibition of iNOS gene expression and NO production, and antagonistic upregulation of arginase gene expression and activity, which created favorable conditions for heart parasitism and myocarditis development.