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In an attempt to improve immune responses and protective efficacy,we constructed tworecombinant bacille Calmette-Guérin(rBCG)strains expressing an 85B antigen(Ag85B)and early secretedantigenic target-6 kDa antigen(ESAT6)of M vcobacterium tuberculosis(MTB)fusion protein.Both rBCGstrains have the same protein insertion but in a different order(Ag85B-ESAT6 and ESAT6-Ag85B).Thecultured supernatant of rBCG strains and the sera from the mice immunized with the fusion protein Ag85B-ESAT6 or ESAT6-Ag85B formed a band with a fraction size of 37 kDa,equalivalent to the sum of Ag85B andESAT6.Six weeks after BALB/c mice were immunized with BCG or rBCG,spleen lymphocytes showedsignificant proliferation in response to culture filtrate protein of MTB.Compared with the BCG group,micevaccinated with rBCG elicited a high level increase of immunoglobulin G antibodies to culture filtrate proteinin the serum.The γ-interferon levels in the lymphocyte culture medium supernatants increased remarkably inthe rBCG1 group,significantly higher than that of the BCG immunized group(P<0.05).Four weeks aftervaccination,mice were infected with M.tuberculosis H37Rv and a dramatic reduction in the numbers ofMTB colony forming units in the spleens and lungs was observed in the two rBCG immunization groups.Although these rBCG strains were more immunogenic,their protective effect was comparable to the classicalBCG strain,and there were no significant differences between two rBCG groups(P>0.05).
In an attempt to improve immune responses and protective efficacy, we constructed tworecombinant bacille Calmette-Guérin (rBCG) expressing an 85B antigen (Ag85B) and early secretedantigenic target-6 kDa antigen (ESAT6) of M vcobacterium tuberculosis (MTB) fusion protein. Both rBCGstrains have the same protein insertion but in a different order (Ag85B-ESAT6 and ESAT6-Ag85B). The culture supernatant of rBCG strain and the sera from the mice immunized with the fusion protein Ag85B-ESAT6 or ESAT6-Ag85B formed a band with a fraction size of 37 kDa, equalivalent to the sum of Ag85B and ESAT6.Six weeks after BALB / c mice were immunized with BCG or rBCG, spleen lymphocytes showedsignificant proliferation in response to culture filtrate protein of MTB.Compared with the BCG group, micevaccinated with rBCG elicited a high level increase of immunoglobulin G antibodies to culture filtrate protein the the. The γ-interferon levels in the lymphocyte culture medium supernatants increased remarkably inthe rBCG1 group, significantly higher than that of the BCG immunized group (P <0.05). Fours weeks aftervaccination, mice were infected with M. tuberculosis H37Rv and a dramatic reduction in the numbers of MTB colony forming units in the spleens and lungs was observed in the two rBCG immunization groups. Although these rBCG strains were more immunogenic, their protective effect was comparable to the classical BCG strain, and there were no significant differences between the two rBCG groups (P> 0.05).