The ideal vaccine induces a potent protective immune response, which should be rapidly induced, long-standing, and of broad specificity. Recombinant adenoviral vectors induce potent Ab and CD8+ T cell responses against transgenic Ags within weeks of administration, and they are among the most potent and versatile Ag delivery vehicles available. However, the impact of chronic infections like HIV and hepatitis C virus underscore the need for further improvements. In this study, we show that the protective immune response to an adenovirus-encoded vaccine Ag can be accelerated, enhanced, broadened, and prolonged by tethering of the rAg to the MHC class II-associated invariant chain (Ii). Thus, adenovirus-vectored vaccines expressing lymphocytic choriomeningitis virus (LCMV)-derived glycoprotein linked to Ii increased the CD4+ and CD8+ T cell stimulatory capacity in vitro and in vivo. Furthermore, mice vaccinated with a single dose of adenovirus-expressing LCMV-derived glycoprotein linked to Ii were protected against lethal virus-induced choriomeningitis, lethal challenge with strains mutated in immunodominant T cell epitopes, and systemic infection with a highly invasive strain. In therapeutic tumor vaccination, the vaccine was as efficient as live LCMV. In comparison, animals vaccinated with a conventional adenovirus vaccine expressing unmodified glycoprotein were protected against systemic infection, but only temporarily against lethal choriomeningitis, and this vaccine was less efficient in tumor therapy.

CD1 molecules play an important role in the immune system, presenting lipid-containing antigens to T and NKT cells. CD1 genes have long been thought to be as ancient as MHC class I and II genes, based on various arguments, but thus far they have been described only in mammals. Here we describe two CD1 genes in chickens, demonstrating that the CD1 system was present in the last common ancestor of mammals and birds at least 300 million years ago. In phylogenetic analysis, these sequences cluster with CD1 sequences from other species but are not obviously like any particular CD1 isotype. Sequence analysis suggests that the expressed proteins bind hydrophobic molecules and are recycled through intracellular vesicles. RNA expression is strong in lymphoid tissues but weaker to undetectable in some nonlymphoid tissues. Flow cytometry confirms expression from one gene on B cells. Based on Southern blotting and cloning, only two such CD1 genes are detected, located Ϸ800 nucleotides apart and in the same transcriptional orientation. The sequence of one gene is nearly identical in six chicken lines. By mapping with a backcross family, this gene could not be separated from the chicken MHC on chromosome 16. Mining the draft chicken genome sequence shows that chicken has only these two CD1 genes located Ϸ50 kb from the classical class I genes. The unexpected location of these genes in the chicken MHC suggests the CD1 system was present in the primordial MHC and is thus Ϸ600 million years old.evolution ͉ paralogy ͉ antigen presentation ͉ nonclassical ͉ avian M HC class I and II molecules play crucial roles in the immune system by presenting peptide antigen to T lymphocytes, as well as natural killer cells recognizing class I molecules. Both MHC class I and II genes have been described in all jawed vertebrates (including bony and cartilaginous fish) and are thought to have arisen at the same time as recombination activating, T cell receptor, and antibody genes Ϸ600 million years ago (1-3).CD1 molecules play an equally important role in the immune system, presenting lipid, glycolipid, and lipopeptide antigens to T and NKT cells (4-8). CD1 genes have long been thought to be as ancient as class I and II genes, based on several pieces of evidence, but thus far they have been described only in mammals (4, 9-11).That the CD1 system is related to MHC class I and II systems is clear, but the details of the evolutionary relationship are not (4 -8). By comparison of gene and protein sequences as well as 3D folds, CD1 is equally related to class I and II sequences and proteins. However, by intron͞exon structure and domain organization, CD1 is similar to class I genes and molecules, with a single transmembrane glycoprotein heavy chain of three extracellular domains that binds ␤ 2 -microglobulin (compared to class II genes and molecules, with two transmembrane glycoproteins, each of two extracellular domains). Conversely, CD1 molecules resemble class II molecules in terms of extensive intracellular trafficking, antigen loading in intracellu...

Antigen-specific immunotherapy is an attractive strategy for cancer control. In the context of antiviral vaccines, adenoviral vectors have emerged as a favorable means for immunization. Therefore, we chose a strategy combining use of these vectors with another successful approach, namely linkage of the vaccine antigen to invariant chain (Ii). To evaluate this strategy we used a mouse model, in which an immunodominant epitope (GP33) of the LCMV glycoprotein (GP) represents the tumor-associated neoantigen. Prophylactic vaccination of C57BL/6 mice with a replication-deficient human adenovirus 5 vector encoding GP linked to Ii (Ad-Ii-GP) resulted in complete protection against GP33-expressing B16.F10 tumors. Therapeutic vaccination with Ad-Ii-GP delayed tumor growth by more than 2 wk compared with sham vaccination. Notably, therapeutic vaccination with the linked vaccine was significantly better than vaccination with adenovirus expressing GP alone (Ad-GP), or GP and Ii unlinked (Ad-GP1Ii). Ad-Ii-GP-induced tumor control depended on an improved generation of the tumor-associated neoantigen-specific CD8 1 T-cell response and was independent of CD4 1 T cells. IFN-c was shown to be a key player during the tumor degradation. Finally, Ad-Ii-GP but not Ad-GP vaccination can break the immunological non-reactivity in GP transgenic mice indicating that our vaccine strategy will prove efficient also against endogenous tumor antigens. often a pre-established state of non-reactivity towards the tumor cells, which has to be broken [2,3]. CD8 1 T cells are believed to be particularly important for immune-mediated tumor degradation [4][5][6][7], and for this reason, a vaccine capable of inducing a strong CD8 1 T-cell response is a major goal in the field of tumor immunology. Replication-deficient adenoviruses have been found to be very effective vaccine vectors, as they mimic a natural infection and trigger the right kind of innate immune response, which is a pre-condition for the development of an effective Th1/Tc1 response to the vaccine-encoded antigen [1,8,9]. Moreover, we have recently shown that the adenovector-induced T-cell response can be even further augmented by linkage of the vaccine antigen to the invariant chain (Ii) [10]. The molecular mechanisms underlying the improved efficiency of this construction are yet to be worked out in detail; however, it is evident from our recent studies that tethering of an antigen to Ii leads to augmented antigen presentation on the surface of DC as evidenced both by T-cell stimulation in vitro and by direct cell-surface binding of an antibody with a specificity similar to that of a TCR (MHC plus peptide) [10,11]. Irrespective of the underlying molecular mechanism, the clinical effect is clear as illustrated by the rapid and very efficient protection of vaccinated mice against an otherwise lethal challenge with lymphocytic choriomeningitis virus (LCMV) [10]. Analysis of the immune response in mice receiving the linked vaccine revealed a remarkable increase in the induced CD8 1 T-cell re...

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