Analysis of Immune Responses against a Wide Range of Mycobacterium tuberculosis Antigens in Patients with Active Pulmonary Tuberculosis

Abstract

e Characterizing host immune responses to molecular targets of Mycobacterium tuberculosis is essential to develop effective immunodiagnostics and better vaccines. We investigated the immune response against a large series of M. tuberculosis antigens, including 5 classical and 64 nonclassical (39 DosR regulon-encoded, 4 resuscitation-promoting factor [RPF], and 21 reactivation-associated) antigens in active-pulmonary-tuberculosis (TB) patients. Whole blood from TB patients (n ‫؍‬ 34) was stimulated in vitro with M. tuberculosis antigens. Gamma interferon (IFN-␥) was measured after 7 days of stimulation, using an enzyme-linked immunosorbent assay (ELISA). The majority of the study participants responded to the classical M. tuberculosis antigens TB10.4 (84.8%), early secreted antigenic target-6 kDa (ESAT-6)/CFP-10 (70.6%), and purified protein derivative (PPD) (55.9%). However, only 26.5% and 24.2% responded to HSP65 and Ag85A/B, respectively. Of the 64 nonclassical antigens, 23 (33.3%) were immunogenic (IFN-␥ levels, >62 pg/ml) and 8 were strong inducers of IFN-␥ (IFN-␥ levels, >100 pg/ml). The RPF antigens were the most immunogenic. In addition, we observed distinct cytokine expression profiles in response to several M. tuberculosis antigens by multiplex immunoassay. Tumor necrosis factor alpha (TNF-␣), interleukin 10 (IL-10), and IL-6 were commonly detected at high levels after stimulation with 4/15 latency antigens (Rv0081, Rv2006, Rv2629, and Rv1733c) and were found especially in supernatants of the three strong IFN-␥ inducers (Rv2629, Rv1009, and Rv2389c). IL-8, IL-6, and IL-17 were exclusively detected after stimulation with Rv0574c, Rv2630, Rv1998, Rv054c, and Rv2028c. In conclusion, in active-pulmonary-TB patients, we identified 23 new immunogenic M. tuberculosis antigens. The distinct expression levels of IFN-␥, TNF-␣, IL-6, and IL-10 in response to specific subsets of M. tuberculosis antigens may be promising for the development of immunodiagnostics.

Tuberculosis vaccine with high predicted population coverage and compatibility with modern diagnostics

“…Combined, these results suggest that an Ag85-specific adaptive immune response primed by vaccination should be effective in the early stage of infection but of relative low value during the later stages of infection. In support of this, a recent study showed that in patients with active pulmonary TB, less than 25% of the patients responded to Ag85A/B proteins, and that these responses in general were very modest (8). In contrast, more than 70% of the patients responded to the early secretory antigenic target-6 and culture filtrate protein 10 (ESAT-6-CFP10) fusion protein and the TB10.4 protein with overall strong Agspecific responses.…”

Evaluation of cytokine and chemokine response elicited by Rv2204c and Rv0753c to detect latent tuberculosis infection

“…Further studies involving functional genomic analysis have shown, it as one of the highly expressed genes during the log phase growth of M. tb [13] and so far there are no notable immunological studies on this protein. The other selected antigen, Rv0753c is one of the reactivation proteins, which might be involved in reactivation of dormant M. tb to active form [14] and is also predicted as a probable methyl melonate semialdehyde dehydrogenase (mmsA) involved in the intermediate respiratory metabolism.…”

Resuscitation-promoting factors are important determinants of the pathophysiology inMycobacterium tuberculosisinfection

“…Studies have confirmed that Rpf are immunogenic in humans generating significant immune responses in both patients with active and latent disease (Chegou et al, 2012;Kassa et al, 2012;Riano et al, 2012). All Rpf proteins appear to be immunogenic with significant Tcell responses demonstrable in LTBI patients using interferon gamma release assays (IGRAs) (Commandeur et al, 2011;Geluk et al, 2014;Huang et al, 2013;Riano et al, 2012;Schuck et al, 2009).…”