| The emergence of new viruses and antibiotic-resistant bacteria has demonstrated the need for new vaccines. DNA vectors, when injected in mice, can elict strong cytotoxic T cell (CTL) responses when compared to peptide vaccines. I have constructed plasmids that express the H-2Dd-restricted CTL epitope HIV gp120(318–327) and the H-2Ad-restricted T H epitope ovalbumin OVA (323–339). In addition, they encode sorting sequences that direct these epitopes into the class I or class II antigen presentation pathways.; The goal of this dissertation was to enhance the gp120-specific CTL response elcited by the DNA plasmids, by examining three aspects affecting the CTL response. First, I wanted to determine whether the identity of the signal sequence can alter the cell-mediated response induced by a DNA epitope vaccine. Therefore, I replced the existing leader derived from the H-2Ld molecule with a leader from the rat KC chemokine, and showed this plasmid elicits an enhanced immune response.; Second, I replaced the OVA (323–339) epitope with variants of the same epitope that have different bidning affintites for the Ad molecule in order to assess the effect on the magnitude of the gp120-specific CTL response. In one RAOMLL, I replaced the wild type with a variant in which the anchor residue valine 327 has been either side of the core region, have been replaced with the sequences YTYT. The presence of the high affinity helper epitope enahcned the CTL response.; Finally, I introduced chemokine sequences to assess their effect on the CT responses generated by the DNA epitope vaccines. More specifically, I used the mouse KC chemokine, known to attract neutrophils, and a series of truncated variants and examined whether their use can improve the gp120-specific CTL response. The presence of these sequences did enhance the immunogenicity of the DNA vaccines. |
