Proteins and Peptides Encoded by M. tuberculosis-Specific Genomic Regions for Immunological Diagnosis of Tuberculosis

Abstract

Copyright: © 2012 Mustafa AS. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Tuberculosis (TB) is a major global health problem with about 9 million new cases and 1.7 million deaths annually [1]. The world-wide problem of TB is expected to worsen in the future due to many reasons, including the spread of drug-resistant strains of Mycobacterium tuberculosis, and TB-HIV co-infection [1]. In addition to new drugs at affordable prices, the global control of TB requires cost-effective reagents for specific diagnosis and protective vaccines [2]. At present, among the commonly used strategies to control TB in the world are the diagnoses of TB using the purified protein derivative (PPD) of M. tuberculosis in delayed-type hypersensitivity (DTH) skin responses, and immunization with Mycobacterium bovis BCG as a vaccine. However, the current data demonstrates that both of these modalities have failed to control the world-wide problem of TB [1].The major limitation of PPD is its inability to differentiate between individuals vaccinated with BCG, infected with M. tuberculosis and exposed to environmental non-tuberculous mycobacteria [3]. This is because PPD is a crude mixture of hundreds of proteins present in the culture supernatant of in vitro grown M. tuberculosis and contains both species-specific as well as crossreactive antigens [3]. On the other hand, BCG vaccination imparts inconsistent protection against TB in different parts of the world, in people of various age groups and against different clinical manifestations of the disease, which suggest that BCG may be lacking in some important antigens of M. tuberculosis required for optimal induction of protective immunity [3]. Therefore, for diagnostic as well as vaccine applications, the identification of M. tuberculosis-specific antigenic proteins may be essential [4].