**8. Hsps in TB diagnosis**

In high-TB incidence countries, TB control relies on diagnosis which is mainly based on clinical symptoms or laboratory diagnosis using sputum smear microscopy. TB smear microscopy is highly insensitive for HIV-co-infected individuals and for children due to the reduced pulmonary bacillary loads in these patients. TB diagnosis by smear microscopy is usually further confirmed by culture. However, this requires extended incubation times and is significantly more expensive than smears, requiring specialized equipment and highly trained personnel (Parsons et al., 2004; Storla et al., 2008). Thus, there is a basic need for the development of fast and inexpensive ways of TB diagnosis.

Using recombinant DNA techniques, synthetic peptides, antigen-specific antibodies and T cells, several major antigens of *M. tuberculosis* have been identified which include hsp60, hsp70, Ag85, ESAT-6 and CFP10 (Mustafa, 2001). In addition, Hsp65, Hsp71, 14-kDa Hsp and GroE proteins can play an important role in the diagnosis of TB. The identification of these markers can contribute to the clinical diagnosis of TB and may also provide additional insight into the pathogenesis of TB (Kashyap et al., 2010). sHsp18 has been shown to be a major immunodominant antigen of *M. leprae* (Lini et al., 2008). Hsp65 has been shown to be an attractive marker for TB (Bothamley et al., 1992; Haldar et al., 2010; Lee et al., 1994; Rambukkana et al., 1991). The 65 kDa heat shock protein is detected even in the cerebrospinal fluid of tuberculous meningitis patients, indicating its potential use as a diagnostic marker for tuberculous meningitis (Mudaliar et al., 2006). In case of TB ascites, the ascitic fluid has shown the presence of Hsp65, Hsp71 and Hsp14 as very useful diagnostic markers (Kashyap et al., 2010). A multiplex PCR against Hsp65 gene coding for 65 kDa antigen for early detection has been tested. The technique was able to distinguish between strains of the *M. tuberculosis* complex and non-tuberculous mycobacteria (Bhattacharya et al., 2003).

The response to recombinant 10-kDa heat shock protein of *M. leprae* was evaluated by indirect ELISA in sera from leprosy patients, household contacts, tuberculosis patients and healthy controls. However, this test seems to have a low sensitivity and specificity for leprosy detection and tuberculosis patients sera cross-reacted with *M. leprae* antigen as well (Rojas et al., 1997).
