g. PIM2), mycolyl arabinogalactan–peptidoglycan complex, phospholipase 17-AAG mw C and lipoproteins, also have the potential to induce iNOS expression.23,26 The hypothetical protein coded by M. tuberculosis open reading frame (ORF) Rv2626c has been shown to elicit a high serum antibody response in patients with active TB, suggesting that this antigen is important in immunoprofiling of disease states.27Rv2626c expression was up-regulated in hypoxic conditions28 and found in culture filtrates as well as in lysates in peptide mass fingerprinting and immune detection studies using an in vitro latency

model. 29 Further studies in mice showed increased expression of Rv2626c at the terminal stages of infection in the lungs. Rv2626c and other M. tuberculosis ORFs encoding α-crystallin (acr), Rv2623, sodC, sodA and fbpB were found to be differentially expressed in IFN-γ deleted mice. An increase in T helper type 1 (Th-1)-mediated immune responses (IFN-γ/iNOS induction) correlated well with increased mRNA synthesis of Rv2626c in M. tuberculosis, suggesting its up-regulation

under stress conditions.30 Studies selleck products using real-time reverse transcription–polymerase chain reaction (RT-PCR) to monitor Rv2626c mRNA synthesis just prior to stress-induced reduction of bacterial multiplication have suggested a role of Rv2626c as a transcription signature for non-replicating persistence.30 In another study where the eight DosR regulon-encoded antigens (Rv1733c, Rv1738, Rv2029c, Rv2031c, Rv2032, Rv2627c, Rv2628 and Rv2626c) were analysed for their immunogenicity in BALB/c and C57BL/6 mice following vaccination with DNA constructs, it appeared that Rv2626c and Rv2031 could provide strong humoral and/or cellular Th-1 responses.31 Furthermore, peripheral blood mononuclear cells (PBMCs) from M. tuberculosis-infected patients recognize Rv2626c and induce major Th-1 cytokines such as IFN-γ.32 A correlation between increased expression of Rv2626c (and the other M. tuberculosis ORFs Rv3286c, Rv2031 and Rv3133c) and phenotypical tolerance of Mycobacterium bovis BCG to rifampicin and metronidazole under anaerobic growth conditions has been

SPTLC1 found.33 In the present study we describe the immunostimulatory role of the secretory 16-kDa conserved hypothetical protein coded by the M. tuberculosis ORF Rv2626c. Our study shows that recombinant Rv2626c (rRv2626c) binds to the surface of murine macrophages and up-regulates NO production and iNOS expression. In addition, we report that rRv2626c induces the expression and secretion of pro-inflammatory as well as Th-1 type cytokines such as TNF-α, IL-12 and IFN-γ as well as the up-regulation of various costimulatory molecules such as B7-1, B7-2 and CD40. We further show that the induction of iNOS expression and NO production by rRv2626c is mediated through the nuclear factor (NF)-κB-dependent pathway. The ORF encoding the hypothetical protein Rv2626c of M.