CD8+ T cell response in HLA-A*0201 transgenic mice is elicited by epitopes from SARS-CoV S protein

Abstract

Cytotoxic CD8(+) T lymphocytes (CTLs) play an important role in antiviral immunity. Several human HLA-A*0201 restricted CTL epitopes of severe acute respiratory syndrome (SARS) spike (S) protein have been identified in HLA-A*0201 transgenic (Tg) mice, but the mechanisms and properties of immune responses are still not well understood. In this study, HLA-A*0201 Tg mice were primed intramuscularly with SARS S DNA and boosted subcutaneously with HLA-A*0201 restricted peptides. The lymphocytes from draining lymph nodes, spleens and lungs were stimulated with the cognate peptides. Three different methods (ELISA, ELISPOT and FACS) were used to evaluate the immune responses during short and long periods of time after immunization. Results showed that peptide-specific CD8(+) T cells secreted IFN-γ, TNF-α and IL-2 and expressed CD107a/b on cell surface. IFN-γ(+)CD8(+) T cells and CD107a/b(+)CD8(+) T cells distributed throughout the lymphoid and non-lymphoid tissues, but the frequency of peptide-specific CD8(+) T cells was higher in lungs than in spleens and lymph nodes. The phenotype of the CD8(+) T cells was characterized based on the expression of IFN-γ. Most of the HLA-A*0201 restricted peptide-specific CD8(+) T cells represented a memory subset with CD45RB(high) and CD62L(low). Taken together, these data demonstrate that immunization with SARS S DNA and HLA-A*0201 restricted peptides can elicit antigen-specific CD8(+) T cell immune responses which may have a significant implication in the long-term protection. We provide novel information in cellular immune responses of SARS S antigen-specific CD8(+) T cells, which are important in the development of vaccine against SARS-CoV infection.

The immune responses of HLA-A*0201 restricted SARS-CoV S peptide-specific CD8+ T cells are augmented in varying degrees by CpG ODN, PolyI:C and R848

“…In our previous studies, we have shown that peptide-specific IFN-␥-producing cells induced by peptides19-23 belonged to CD8 + T cells but not CD4 + T cells. Peptide19-23 as HLA-A*0201 restricted peptides could act as stimulators to elicit a striking peptide-specific CTL response [13]. In the present study, we still found that there was no cytokine production in CD4 + T cells following cognate peptides stimulation, which were consistent with the previous results (data not shown).…”

“…(Shanghai, China). These five peptides were named as P19 (S1042-1050 VVFLHVTYV), P20 (S787-795 ILPDPLKPT), P21 (S1167-1175 RLNEVAKNL), P22 (S958-966 VLNDILSRL) and P23 (S411-420 KLPDDFMGCV) were identified by us and other groups before [13,14,[16][17][18]. Peptides were purified to >98% by reverse phase HPLC, as confirmed by mass spectrometry, which were dissolved in PBS at 2 mg/ml and stored in aliquots at −80 • C.…”

“…tive approaches [9][10][11][12]. With regard to SARS-CoV, there have been many T cell epitopes identified by us and other groups [13][14][15][16][17][18]. In our previous study, we have identified five epitopes for CD8 + T cells in HLA-A*0201 transgenic mouse by "DNA prime, peptide boost" strategy [13].…”

“…With regard to SARS-CoV, there have been many T cell epitopes identified by us and other groups [13][14][15][16][17][18]. In our previous study, we have identified five epitopes for CD8 + T cells in HLA-A*0201 transgenic mouse by "DNA prime, peptide boost" strategy [13]. However, their poor immunogenicity emphasizes a major unmet need for immunostimulatory adjuvants to safely boost cellular immune responses.…”

T-cell immunity of SARS-CoV: Implications for vaccine development against MERS-CoV

“…Different adjuvants have been investigated to increase the efficacy of peptide vaccines. Surface-linked liposomal peptide ), muramyl dipeptide derivative adjuvant (Chen et al, 2010b), and CpG oligodeoxynucleotide (CpG ODN) (Zhao et al, 2010b can augment peptidespecific T-cell responses, some of the which are protective (Du et al, 2010(Du et al, , 2009b(Du et al, , 2008Zhao et al, 2010a) and durable (Du et al, 2008;Kohyama et al, 2009;Yang et al, 2009). Virus-like particle (VLP) vaccines containing S protein as the dominant immunogen and adjuvanted with aluminum provided protection against mice challenged with SARS-CoV (Liu et al, 2011c;Lokugamage et al, 2008).…”