Expression and immunogenicity of recombinant Mycobacterium bovis Bacillus Calmette-Guérin strains secreting the antigen ESAT-6 from Mycobacterium tuberculosis in mice

Background Tuberculosis remains the leading cause of human death. Currently, Bacillus Calmette-Guerin （BCG） is the only available vaccine against tuberculosis but its efficacy is highly variable. Thus, developing new tuberculosis vaccines becomes an urgent task. In this study, we evaluated in BALB/c mice the humoral and cellular immune responses of recombinant BCG expressing the antigen ESAT-6 from Mycobacterium tuberculosis. Methods Escherichia coli-BCG shuttle plasmid named pDE22-esat-6 was constructed by inserting the BamHI/EcoRI digested esat-6 gene PCR product into the similarly digested parental plasmid pDE22. BCG cells were transformed with pDE22-esat-6, which was named recombinant BCG （rBCG）. BALB/c mice were immunized subcutaneously on the back with 100 μl normal saline containing 106 CFU of BCG or rBCG. They were sacrificed after 4 weeks to detect their humoral and cellular responses. Results There was no any significant differences in the growth characteristics between the conventional BCG and rBCG. In immunized mice, the IgG antibody titres of rBCG group were as high as 1：8000, which was significantly higher than that in BCG group （1：1400, P〈0.05）. The elicited IFN-γ, level of rBCG group was （1993 ± 106） pg/ml, which was also significantly higher than that in BCG group （（1463 ± 105） pg/ml, P〈0.05）. The splenocyte proliferation index of rBCG group reached 4.34 ± 0.31, which was higher than that of BCG group （3.79 ±0.24, P〈0.05）. Conclusion rBCG secreted expressing antigen ESAT-6 stimulated stronger humoral and cellular immune responses than BCG did, and, therefore may be the better vaccine against mycobacterium tuberculosis.     

New insights into the effects of Mycobacterium bovis Bacillus Calmette-Guérin on asthma

Allergic asthma has been defined as a disease of immunodysregulation, where the pathology is a direct consequence of excessive T-helper type 2 immune responses （Th2） to allergens in the lungs. Disease is associated with increased secretion of type-2 cytokines such as interleukin （IL）-4, IL-5 and IL-13 which, among other things,     

Cloning and expression of the fusion protein of interleukin-2 and ESAT6 in Mycobacterium bovis Bacillus Calmette Guérin strain

Tuberculosis(TB)isthemostcommoncauseofdeathininfectiousdiseases; itisestimatedthatapproximately2millionpeopleperyeardieofTB ThepresentavailableTBvaccineisaliveattenuatedstrain,MycobacteriumbovisBacillusCalmetteGuérin (BCG) However, ithasbeenshownthatBCGhasvariableprotectiveefficacy, rangingfrom 0 to85% indifferentclinicalexperiments 1 Therefore, anewTBvaccineisurgentlyneeded Manytrialshavebeendonetodevelopthesecond generationTBvaccinesinrecentyears; candidatesincludeavirulent, auxotro…     

Detection of the mutations in katG315 and inhA-15 of Mycobacterium tuberculosis strains isolated from Chinese patients

The situation of tuberculosis and M. tuberculosis （MTB） drug resistance is severe in China.Among the MTB isolates, 27.8% were resistant to one primary antituberculosis drug at least. Isoniazid （INH） is one of the first-line anti-TB drugs. The rates of primary resistance and acquired resistance to INH were 11.0% and 31.0%, respectively. MTB strains resistance to INH is mainly caused by the alterations in several genes encoding the molecular targets as follows： catalase peroxidase （katG）,