Plasmid having three complete transcriptional units and immunogenic compositions for inducing an immune response to hiv

Abstract

The invention provides a DNA plasmid comprising: (a) a first transcriptional unit comprising a nucleotide sequence that encodes a first polypeptide operably linked to regulatory elements including a first promoter and a first polyadenylation signal; (b) a second transcriptional unit comprising a nucleotide sequence that encodes a second polypeptide operably linked to regulatory elements including a second promoter and a second polyadenylation signal; (c) a third transcriptional unit comprising a nucleotide sequence that encodes a third polypeptide operably linked to regulatory elements including a third promoter and a third polyadenylation signal; and wherein said first, said second and said third promoters are each derived from different transcriptional units; and wherein said first, said second and said third polyadenylation signals are each derived from different transcriptional units. The invention further relates to immunogenic compositions for inducing an immune response to HIV comprising combinations of two, three, or four plasmids, where each plasmid is expressing a defined antigen, which may be a single antigen or a fusion of two or three antigens.

Description

FIELD OF THE INVENTION [0001] This invention relates to plasmids, immunogenic compositions and methods to improve prophylactic and therapeutic immune responses to antigens. BACKGROUND OF THE INVENTION [0002] Immunization using plasmid DNA-based immunogenic compositions is a powerful tool that is useful for developing approaches to prevent or treat infectious diseases or in the treatment of ongoing disease processes. Plasmid DNA immunization has been extensively tested in animal models where it has been found to be effective in inducing both cellular and humoral immune responses against a wide variety of infectious agents and tumor antigens. See Donnelly J J, et al., Ann. Rev. Immunol.; 15: 617-48 (1997); Iwasaki A, et al., J Immunol 158 (10): 4591-601 (1997); Wayne, C. L. and Bennett M., Crit. Rev. Immunol., 18: 449-484 (1998). [0003] An important advantage of plasmid DNA immunization is that genes can be cloned, modified and positioned into a potential plasmid DNA expression vector...

AI Technical Summary

Benefits of technology

[0036] In a particular embodiment, the present invention provides an immunogenic composition for inducing an immune response to HIV in a vertebrate host, where the immunogenic composition comprises five plasmids as described above, and where each plasmid further comprises a selectable marker selected from the group con

Problems solved by technology

While, viral regulatory elements are advantageous for use in plasmid DNA vectors, the use of unmodified viral vectors to express the relevant genes may raise safety and technical issues not encountered with plasmid DNA.

Current plasmid DNA designs, however, limit the expression of multiple genes from one vector backbone in a single target cell.

When cells must be co-transfected with multiple plasmids, it is difficult to achieve optimal expression of all encoded genes, especially when the plasmid is being used in vivo.

None of the existing plasmid designs have solved the problem of providing a DNA plasmid suitable for expressing more than two independent open reading frames in human immunogenic compositions.

The presence of homologous sequences within a plasmid renders that plasmid unsuitable for use in DNA immunogenic compositions, because the presence of homologous sequences within the plasmid backbone increases the possibility of recombination between the repeated sequences and results in vector instability.

As transcriptional units are added to a plasmid, interference between transcriptional units can arise, for example in the form of steric hindrance.

Simply making the plasmid bigger is not necessarily the best solution for several reasons including plasmid instability, difficulty in plasmid manufacture and, most importantly, dosing considerations.

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