Open Access
Identification of Mycobacterium tuberculosis Ornithine Carboamyltransferase in Urine as a Possible Molecular Marker of Active Pulmonary Tuberculosis
Author(s) -
Danielle R. Napolitano,
Nira R. Pollock,
Suely S. Kashino,
Virmondés Rodrigues,
Antônio Campos-Neto
Publication year - 2008
Publication title -
clinical and vaccine immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.649
H-Index - 77
eISSN - 1556-6811
pISSN - 1556-679X
DOI - 10.1128/cvi.00010-08
Subject(s) - tuberculosis , mycobacterium tuberculosis , antigen , antibody , western blot , tuberculin , latent tuberculosis , urine , biology , immunology , medicine , microbiology and biotechnology , virology , pathology , biochemistry , gene
Although the antigen detection assay has the potential to discriminate active tuberculosis from latent infection, development of such a test for the accurate diagnosis of this serious disease has only recently become a matter of interest. Here we present evidence that aMycobacterium tuberculosis protein (ornithine carboamyltransferase, coded for by MT_1694; Rv1656 [argF ]) is an interesting candidate molecule for this test development. The protein was initially discovered by mass spectroscopy in urine of patients with pulmonary tuberculosis and shown by Western blot analysis to be present inM. tuberculosis crude cell extract as well as in the culture supernatant (“secreted” protein). In addition, a recombinant ornithine carboamyltransferase (rMT1694) produced inEscherichia coli was recognized by immunoglobulin G (IgG) antibodies from patients with active tuberculosis but not by IgG from uninfected healthy subjects. Moreover, rMT1694 was strongly recognized by peripheral blood mononuclear cells from both healthy tuberculin purified protein derivative (PPD)-positive individuals and patients with pulmonary tuberculosis. More importantly, a capture enzyme-linked immunosorbent assay formatted with rabbit IgG antibodies specific to rMT1694 was able to identify the presence of this antigen in urine samples from 6 of 16 patients with pulmonary tuberculosis and in none of 16 urine samples collected from healthy PPD+ controls. These results indicate that an improved antigen detection assay based onM. tuberculosis ornithine carboamyltransferase may represent an important new strategy for the development of a specific and accurate diagnostic test for tuberculosis.