Title
Identification of a novel protein antigen encoded by a Mycobacterium tuberculosis-specific RD1 region gene
Author
Ahmad, S.
Amoudy, H.A.
Thole, J.E.R.
Young, D.B.
Mustafa, A.S.
TNO Preventie en Gezondheid
Publication year
1999
Abstract
A genomic DNA region, designated RD1, that is present in virulent and clinical strains of Mycobacterium tuberculosis and M. bovis, has been shown to be deleted in bacillus Calmette Guerin (BCG). The DNA segments corresponding to three open reading frames (ORFs: ORF-10, ORF-14 and ORF-15) of the RD1 region, that are deleted in BCG strains, were amplified from M. tuberculosis genomic DNA by polymerase chain reaction (PCR), subcloned into pGEX-4T vector system and expressed in Escherichia coli as fusion proteins with glutathione-S-transferase (GST). The recombinant proteins appeared as major cellular proteins in SDS-PAGE gels at the expected molecular mass. The identity of each fusion protein was confirmed by reactivity with anti-GST antibodies in Western immunoblots. When pooled human sera from 11 tuberculosis (TB) patients were used as the source of antibodies, only GST- ORF-14 fusion protein reacted in Western immunoblots. The protein corresponding to ORF-14 was then purified to near homogeneity and isolated free of its fusion partner (GST) by treating the purified GST-ORF-14 fusion protein with thrombin protease. In Western immunoblots, the purified ORF-14 protein reacted with antibodies in 26 of 57 human sera (46%) from TB patients while no reactivity was seen with 11 sera from M. bovis BCG-vaccinated healthy subjects. Interestingly, sera from nine of 15 (60%) long-term contacts of TB patients also had antibodies reactive to the ORF-14 protein. These results suggest that the ORF-14 protein in combination with other immunodominant proteins could be useful in the serodiagnosis of individuals infected with M. tuberculosis.
Subject
Health
BCG vaccine
Antibodies, Bacterial
Antigens, Bacterial
Bacterial Proteins
Cloning, Molecular
Escherichia coli
Gene Expression
Genes, Bacterial
Humans
Immunoblotting
Mycobacterium tuberculosis
Open Reading Frames
Recombinant Fusion Proteins
Tuberculosis
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DOI
https://doi.org/10.1046/j.1365-3083.1999.00531.x
TNO identifier
235020
ISSN
0300-9475
Source
Scandinavian Journal of Immunology, 49 (5), 515-522
Document type
article