Immunogenicity of the Mycobacterium tuberculosis PPE55 (Rv3347c) Protein during Incipient and Clinical Tuberculosis

Clinical tuberculosis (TB), whether noncavitary or cavitary, is the late stage of a chronic disease process, since Mycobacterium tuberculosis is a slowly growing organism. Our studies have shown that the profiles of antigenic proteins expressed by the in vivo bacteria that elicit antibodies differ i...

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Bibliographic Details
Published in:Infection and Immunity 2005-08, Vol.73 (8), p.5004-5014
Main Authors: Singh, Krishna K, Dong, Yuxin, Patibandla, Sai A, McMurray, David N, Arora, Vijay K, Laal, Suman
Format: Article
Language:English
Subjects:
Animals
Antibodies - blood
Antibody Formation - immunology
Bacterial diseases
Bacterial Infections
Bacterial Proteins - genetics
Bacterial Proteins - immunology
Biological and medical sciences
Fundamental and applied biological sciences. Psychology
Gene Library
Guinea Pigs
Human bacterial diseases
Humans
Infectious diseases
Medical sciences
Microbiology
Mycobacterium tuberculosis - genetics
Mycobacterium tuberculosis - immunology
Tuberculosis - blood
Tuberculosis - diagnosis
Tuberculosis - immunology
Tuberculosis and atypical mycobacterial infections
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Summary:Clinical tuberculosis (TB), whether noncavitary or cavitary, is the late stage of a chronic disease process, since Mycobacterium tuberculosis is a slowly growing organism. Our studies have shown that the profiles of antigenic proteins expressed by the in vivo bacteria that elicit antibodies differ in cavitary and noncavitary TB (K. Samanich, J. T. Belisle, and S. Laal, Infect. Immun. 69:4600-4609, 2001). To gain insight into antigenic proteins expressed during incipient, subclinical TB, an expression library of M. tuberculosis genomic DNA was screened with sera obtained during subclinical TB from guinea pigs infected with aerosols of M. tuberculosis H37Rv. One of the proteins recognized by antibodies elicited during subclinical TB infection of guinea pigs is the 309-kDa PPE55 (Rv3347c) protein. Genomic hybridization studies suggest that the PPE55 gene is specific to the M. tuberculosis complex and is present in a majority of clinical isolates tested. Antibodies to the C-terminal, [approximately]100-kDa fragment of PPE55 (PPE-C) were detectable in sera from 29/30 (97%) human immunodeficiency virus-negative/TB-positive (HIV⁻ TB⁺) patients and 17/24 (71%) HIV⁺ TB⁺ patients tested but not in sera from purified-protein derivative-positive healthy controls, suggesting that the in vivo expression of PPE55 protein correlates with active M. tuberculosis infection. Anti-PPE-C antibodies were also detected in retrospective sera obtained months prior to manifestation of clinical TB from 17/21 (81%) HIV⁺ TB⁺ individuals tested, providing evidence that the protein is expressed during incipient, subclinical TB in HIV-infected humans. Thus, PPE55 is a highly immunogenic protein that may be useful for differentiating between latent TB and incipient, subclinical TB.
ISSN:0019-9567
1098-5522
DOI:10.1128/IAI.73.8.5004-5014.2005