Mycobacterium tuberculosis HBHA protein reacts strongly with the serum immunoglobulin M of tuberculosis patients.
Identification and characterization of serologically active mycobacterial antigens are prerequisites for the development of diagnostic reagents. We examined the humoral immune responses of active tuberculosis (TB) patients against Triton-soluble proteins extracted from Mycobacterium tuberculosis by immunoblotting. A 29-kDa protein reacted with immunoglobulin M (IgM) in the pooled sera of the patients, and its N-terminal amino acid sequence matched that of the heparin-binding hemagglutinin (HBHA). Recombinant full-length HBHA was expressed in Escherichia coli (rEC-HBHA) and M. smegmatis (rMS-HBHA). In immunoblot analysis, the IgM antibodies of the TB patients reacted strongly with rMS-HBHA but not with rEC-HBHA, whereas the IgG antibodies of these patients reacted weakly with both recombinant HBHA proteins. In enzyme-linked immunosorbent assay analysis using rMS-HBHA and 85B as antigens, the mean levels and sensitivities of the anti-HBHA IgM antibodies of the TB patients were significantly higher than those of the anti-antigen 85B IgM antibodies, while the IgG antibodies showed the opposite results. Of interest in this respect, the pooled sera from the TB patients that contained anti-HBHA IgM antibodies neutralized the entry of M. tuberculosis into epithelial cells. These findings suggest that IgM antibody to HBHA may play a role in protection against extrapulmonary dissemination.
Shin
A-Rum
AR
Department of Microbiology, College of Medicine, Chungnam National University, 6 Muwha-Dong, Jung-Ku, Daejeon 301-747, Korea.
Lee
Kil-Soo
KS
Lee
Ji-Sook
JS
Kim
Su-Young
SY
Song
Chang-Hwa
CH
Jung
Saet-Byel
SB
Yang
Chul-Su
CS
Jo
Eun-Kyeong
EK
Park
Jeong-Kyu
JK
Paik
Tae-Hyun
TH
Kim
Hwa-Jung
HJ
D000818:Animals; D000937:Antigen-Antibody Reactions / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology / Q000378:metabolism; D001426:Bacterial Proteins / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D002460:Cell Line; D002908:Chronic Disease; D006801:Humans; D015151:Immunoblotting; D007075:Immunoglobulin M / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D008565:Membrane Proteins / Q000097:blood / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011994:Recombinant Proteins / Q000097:blood / Q000276:immunology / Q000378:metabolism; D014376:Tuberculosis / Q000276:immunology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C440647:HbhA protein, Mycobacterium tuberculosis; D007075:Immunoglobulin M; D008565:Membrane Proteins; D011994:Recombinant Proteins