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s Tuberculosis causes serious health problem for the world population. Antigenic peptides selected by pathogen-specific cytotoxic T lymphocytes (CTLs) are presented by major histocompatibility complex (MHC; or human leukocyte antigen [HLA] in humans) molecules, and HLA-A restricted responses may be of interest for vaccine development and the understanding of cellular immunity. A series of peptides derived from the 10-KDa culture filtrate protein (CFP10) and the 6 kDa early secretory antigenic target (ESAT-6) in the Mycobacterium tuberculosis (Mtb) have been screened and a CTL epitope restricted by the human leukocyte antigen HLA-A24, a common HLA allele in Asian people, has been identified. In this study, we studied a panel of CFP10 and ESAT-6-derived peptides to identify those with binding motifs for HLA-A24 molecules. The antigenicity of candidate peptides was assessed with in vitro refolding tests and an enzyme-linked immunospot (ELISPOT) assay, and by tetramer staining to determine the capacity to stimulate CTLs from peripheral blood mononuclear cells (PBMCs) of HLA-A24-positive TB Patients. We report that one novel candidate peptide at positions 5–14 of ESAT-6 of Mtb could induce peptide-specific CTLs from PBMCs of HLA-A24-positive patients, but not from HLA-A24-negative patients and HLA-A24-positive healthy controls. Identified epitope is a weak binder for HLA-A24 molecule in a mini MHC refolding assay. Since the peptide is presented by a common HLA class I molecule, it may be useful for immunotherapy against Mtb infection and vaccine development in the large population of Mtb-infected patients., Highlights ► We study a panel of Mtb-derived peptides to identify binders for HLA-A24. ► Peptide P5 significantly elicits IFN-producing CTLs from HLA-A24+ TB donors. ► Peptide P5 is a weak binder for HLA-A24 molecule in a mini refolding assay. ► The identified epitope may be useful for immunotherapy and vaccine development.

Rotavirus-naive and rotavirus-immune gnotobiotic calves were treated with high doses of dexamethasone (DX) to suppress the immune system. Calves were then infected with a virulent rotavirus inoculum, J-160, to investigate the role of immune responses both in recovery from primary rotavirus infection and in resistance to secondary rotavirus infection. Treatment of calves with DX markedly suppressed in vitro responsiveness of peripheral blood lymphocytes to mitogens within 48 h of the start of DX treatment. Suppression was similar in rotavirus-naive and rotavirus-immune calves. In contrast, the effect of DX treatment on specific antibody responses differed depending on when DX treatment started in relation to rotavirus infection. When DX treatment commenced prior to primary rotavirus infection both systemic and local specific antibody responses were inhibited. These calves, in which mitogen and antibody responses were suppressed, exhibited greater clinical signs than did control calves after infection with virulent rotavirus, but virus excretion was affected in only one of the two calves. When DX treatment was started after primary rotavirus infection but before secondary infection, systemic and local antibody responses to the primary infection and to the challenge infection were not affected. These calves resisted challenge with virulent virus as did DX-untreated rotavirus-immune calves, even though mitogen responses were suppressed. We conclude that in a primary rotavirus infection, virus excretion ceased when both antibody and mitogen responses were suppressed. Resistance to secondary rotavirus infection occurred when mitogen responsiveness was suppressed, but when antibody levels were normal. Thus, no evidence was obtained that fully functional cell-mediated immune mechanisms are essential for resistance to rotavirus infection. Evidence was provided for the ability of parenteral treatment with DX to suppress mucosal as well as systemic antibody responses.

Lack of genetic variability and apparent susceptibility of cheetahs (Acinonyx jubatus jubatus) to coronavirus infection has lead to speculation that this species may have immune system deficits. To establish a foundation for evaluation of the immune function, cheetah peripheral blood mononuclear cells (PBM) were stimulated by a panel of six mitogens, and responses compared with those of domestic cat PBM. Individual responses in both species were variable, but evenly distributed throughout the range of stimulation for each mitogen. Proliferation by PBM from domestic cats occurred within the same range as that of the cheetahs. However, a significantly lower response to peanut agglutinin (PNA) was observed with domestic cat PBM. Although responses varied between animals, certain individual cheetahs were consistent low responders. The decreased values could not be explained by lack of IL-2 responsiveness since exogenous IL-2 significantly enhanced mitogen-stimulated proliferation in 11 of 12 cheetahs tested. The phenotypic distribution of domestic cat and cheetah lymphocyte subpopulations was similar as assessed by immunofluorescence staining for surface immunoglobulin (sIg) and cytotoxic T (Tc) cells (using a specific monoclonal antibody, FT2). Values for B cells (31.2% sIg+) and Tc (28.7% FT2+) were slightly higher in domestic cats as compared with cheetah PBM (13.3% sIg+; 19.0% FT2+). Even though no species-specific deficits were detected, a significant negative correlation between PHA-stimulated proliferation and percent FT2+ (Tc) cheetah cells was observed. This indicates that proliferation can be used indirectly to assess relative numbers of functional T helper cells in cheetahs. Our studies suggest that these aspects of the cheetah's immune system are comparable with the domestic cat, and establish a basis for in vitro assays evaluating antigen-specific responses.