Identification of HLA-A2-Restricted Mycobacterial Lipoprotein Z Peptides Recognized by T CellsFrom Patients With ActiveTuberculosis Infection

Abstract

Identification of HLA-restricted peptides derived from mycobacterial antigens that are endowed with high affinity and strong antigenicity is not only of interest in tuberculosis (TB) diagnostics and treatment efficacy evaluation, but might also provide potential candidates for the development of therapeutic vaccines against drug-resistant TB. Our previous work demonstrated that lipoprotein Z (LppZ) displayed high immunogenicity and antigenicity in active TB patients. In the present study, ten HLA-A2-restricted LppZ peptides (LppZp1-10) were predicted by bioinformatics, among which LppZp7 and LppZp10 were verified to possess high affinity to HLA-A2 molecules using T2 cell-based affinity binding assay. Moreover, results from ELISpot assay showed that both LppZp7 and LppZp10 peptides were able to induce more IFN-γ producing cells upon ex vivo stimulation of PBMC from HLA-A2+ active TB (ATB) patients as compared to those from healthy controls (HCs). Also, the numbers of LppZp7 and LppZp10-specific IFN-γ producing cells exhibited positive correlations with those of ESAT-6 peptide (E6p) or CFP-10 peptide (C10p) in ATB. Interestingly, stimulation with LppZp7/p10 mixture was able to induce higher intracellular expression of IFN-γ and IL-2 cytokines in CD8+ and CD4+ T cells from ATB as compared to HC, associated with lower expression of TNF-α in both CD8+ and CD4+ T cells. Taken together, HLA-A2-restricted LppZp7 and LppZp10 peptides display high immunoreactivity in HLA-matched ATB patients demonstrated by high responsiveness in both CD8+ and CD4+ T cells. With the ability to induce strong antigen-specific cellular responses, LppZp7 and LppZp10 are of potential value for the future applications in the prevention and control of TB.

Age-Related Immunoreactivity Profiles to Diverse Mycobacterial Antigens in BCG-Vaccinated Chinese Population

“…Different immunological patterns were revealed under either M.tb infection or neonatal BCG vaccination among E6C10 -, E6C10 + HDs and TB cohorts. Consistent with previous studies (11,12,14,15), Rv3006 is of high immunogenicity upon M.tb infection, with the most IFN-g specific SFUs in TB patients (Figure S1B). However, BCG vaccination does not induce strong immunoreactivity to Rv3006 in E6C10and E6C10 + adults (Figure S1B).…”

“…Rv3006 (also known as lipoprotein Z, LppZ) is both a cell-wall component and a secreting protein (13). Studies from our own and other groups demonstrate that it is of high immunogenicity during M.tb infection triggering both innate and adaptive immunity (11,12,14,15). Rv3841 (also known as BfrB, a ferritin-like protein) is reported to be an iron-storage protein (16).…”

“…However, whether the dominant antigen profiles shift along with the age is not well investigated. In this study, three M.tb and BCG-shared mycobacterial antigens, Rv3006, Rv3841 and Rv0934, were subjected to the investigation due to their different immunogenicity and immunoreactivity upon M.tb infection based on our previous studies (11,12). Rv3006 (also known as lipoprotein Z, LppZ) is both a cell-wall component and a secreting protein (13).…”