Abstract: The invention concerns the optimisation of the wild R9M peptide and the use of the resulting peptides for therapeutic vaccination and/or preventive vaccination against leukemia in humans. More particularly, the invention concerns mutated immunogenic peptides derived from the human TEL/AML1 fusion protein comprising the wild R9M peptide sequence Arg-Ile-Ala-Glu-Czs-Ile-Leu-Gly-Met. The invention also concerns polynucleotides coding for the mutated R9M immunogenic peptides, cellular expression vectors comprising nucleic acid sequences expressing the mutated R9M immunogenic peptides and polyclonal or monoclonal antibodies capable of being fixed on at least one of said peptides/polynucleotides. The invention further concerns the use of said peptides, polynucleotides and/or antibodies for preparing vaccines, anti-tumoral medicines and compositions and for in vitro and in vivo stimulation of the immune response in humans.

Abstract: H-2 class I negative, HLA-A2.1 transgeniic HHD mice were used for a comparative evaluation of the immunogenicity of HLA-A2.1 restricted human tumor-associated CTL epitopes. A hierarchy was established among these epitopic peptides injected into mice in IFA which correlates globally with their capacity to bind and stabilize HLA-A2.1 molecules. Co-injection of a helper peptide enhanced most CTL responses. In contrast, classical HLA class I transgenic mice which still express their own class I molecules did not, in most cases, develop H.A.-A2.1-restricted CTL responses under the same experimental conditions. Different monoepitopic immunization strategies of acceptable clinical usage were compared in HHD mice. Recombinant Ty-virus-like particles, or DNA encoding epitopes fused to the hepatitis B virus middle envelope protein gave the best results. Using this latter approach and a melanoma-based polyepitope construct, CTL responses against five distinct epitopes could be elicited simultaneously in a single animal.

Abstract: A recombinant vector comprising a polynucleotide containing a cis-acting central initiation region (cPPT) and a cis-acting termination region (CTS) is disclosed. These regions are of retroviral or retroviral-like origin. The vector further comprises a defined nucleotide sequence (transgene or sequence of interest) and regulatory signals for reverse transcription, expression, and packaging, wherein the regulatory signals are of retroviral or retroviral-like origin. In some embodiments the vector is incorporated into compositions for therapeutic purposes. In other embodiments the vector is incorporated into immunogenic compositions, The vector is also useful for methods such as ex vivo transfection or ex vivo transduction of non-mitotic differentiated cells.