[Immune response and protective efficacy induced by fusion protein ESAT6-CFP10 of M.tuberculosis in mice].
OBJECTIVE
To study murine humoral and cellular immune response induced by fusion protein ESAT6-CFP10 and to examine its protective efficacy against M. tuberculosis (MTB) in mice.


METHODS
BALB/c mice were immunized subcutaneously on the back with fusion protein ESAT6-CFP10 that was transferred to nitro cellulose (NC) membrane beforehand. Stimulation index (SI) of the spleen lymphocytes of the immunized mice was measured by MTT colorimetry. The level of IFN-gamma and IL-2 and CTL upon antigen-specific stimulation were detected. The vaccinated BALB/c mice were intravenously infected with MTB H37Rv (10(5) CFU/mouse). Four weeks later the number of CFU in spleens was determined.


RESULTS
The titer of serum specific antibody in BALB/c mice immunized with fusion protein ESAT6-CFP10 was 1:6,400. The SI of fusion protein immunized group (1.90+/-0.15) was significantly higher than that of saline-immunized group (0.9+/-0.15). The level of IFN-gamma and IL-2 induced by the fusion protein was 1.792+/-19 ng/L and 0.211+/-11 ng/L respectively, which was significantly higher than that of saline-immunized group and lower than that of BCG-immunized group. The specific killing activity of splenocytes was 36%. Compared with the saline-immunized mice (bacterial load was 6.51+/-0.13), MTB number (bacterial load was 5.24+/-0.15) was reduced dramatically in the spleens of BALB/c mice immunized with the fusion protein, but the protective efficacy of the mice immunized with BCG was higher than that of ESAT6-CFP10 vaccinated group.


CONCLUSIONS
Fusion protein ESAT6-CFP10 can be used as a candidate for novel vaccines.
Zhang
Hai
H
Laboratory Animal Research Center, Fourth Military Medical University, Xi'an 710032, China. hzhang1971@yahoo.com.cn
Shi
Chang-hong
CH
Xue
Ying
Y
Bai
Yin-lan
YL
Wang
Li-mei
LM
Xu
Zhi-kai
ZK
D000818:Animals; D000917:Antibody Formation; D000942:Antigens, Bacterial / Q000235:genetics / Q000276:immunology*; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology*; D049109:Cell Proliferation; D007114:Immunization; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008214:Lymphocytes / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000276:immunology*; D013154:Spleen / Q000166:cytology / Q000378:metabolism
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C117940:CFP-10 protein, Mycobacterium tuberculosis; C093276:ESAT-6 protein, Mycobacterium tuberculosis; D007376:Interleukin-2; D011993:Recombinant Fusion Proteins; D007371:Interferon-gamma