The phenotype and function of antigen-specific CD8 T cells are closely associated with the efficacy of a therapeutic vaccination.Here we showed that multiple immunizations with LCMV gp33-41 peptide(KAV)in Freund's adjuvant could induce KAV-specific CD8 T cells with low expression of CD127 and CD62L molecules.The inhibitory receptor PD-1 was also expressed on a substantial part of KAV-specific CD8 T cells,and its expression level on KAV-specific CD8 T cells in spleen and lymph nodes was much higher when compared to those in peripheral blood.Furthermore,KAV-specific CD8 T cells could specifically kill KAV-pulsed target cells in vivo but the efficiency was low.These data suggest that prime-boost vaccination schedule with peptide in Freund's adjuvant can elicit antigen-specific CD8 T cells of effector-like phenotype with partial functional exhaustion,which may only provide short-term protection against the pathogen.
Chinese-descent rhesus macaques have become more prevalent for HIV infection and vaccine investigation than Indian-origin macaques. Most of the currently available data and reagents such as major histocompatibility complex (MHC) class I tetramers, however, were derived from Indian-origin macaques due to the dominant use of these animals in history. Although there are significant differences in the immunogenetic background between the two macaque populations, they share a few of common MHC class I alleles. We reported in this study the procedure for preparation of a soluble Mamu-B*1703 (a MHC class I molecule of Chinese macaques) monomer and tetramer loaded with a dominant simian immunodeficiency virus (SIV) epitope IW9 (IRYPKTFGW) that was identified to be Mamu-B*1701-restricted in Indian macaques. The DNA fragment encoding the Mamu-B*1703 extracellular domain fused with a BirA substrate peptide (BSP) was amplified from a previously cloned cDNA and inserted into a prokaratic expression vector. In the presence of the antigenic peptide IW9 and light chain β2-microglobulin, the expressed heavy chain was refolded into a soluble monomer. After biotinylation, four monomers were polymerized as a tetramer by phycoerythrin-conjugated streptavidin. The tetramer, having been confirmed to have the right conformation, was a potential tool for investigation of antigen-specific CD8+ T-lymphocytes in SIV vaccine models of Chinese macaques. And our results also suggested that some antigenic peptides reported in Indian-origin macaques could be directly recruited as ligands for construction of Chinese macaque MHC tetramers.
