Molecular vaccine linking intercellular spreading protein to an antigen

Abstract

Superior molecular vaccines comprise nucleic acids, including naked DNA and replicon RNA, that encode a fusion polypeptide that includes an antigenic peptide or polypeptide against which an immune response is desired. Fused to the antigenic peptide is an intercellular spreading protein, in particular a herpes virus protein VP22 or a homologue or functional derivative thereof. Preferred spreading proteins are VP22 from HSV-1 and Marek's disease virus. The nucleic acid can encode any antigenic epitope of interest, preferably an epitope that is processed and presented by MHC class I proteins. Antigens of pathogenic organisms and cells such as tumor cells are preferred. Vaccines comprising HPV-16 E7 oncoprotein are exemplified. Also disclosed are methods of using the vaccines to induce heightened T cell mediated immunity, in particular by cytotoxic T lymphocytes, leading to protection from or treatment of a tumor.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention in the fields of molecular biology, immunology and medicine relates to a chimeric nucleic acid, including DNA and viral RNA encoding a fusion protein and its use as a vaccine to enhance immune responses, primarily cytotoxic T lymphocyte (CTL) responses to specific antigens such as tumor or viral antigens. The fusion protein comprises an antigenic polypeptide fused to a protein that promotes intercellular transport and processing via the MHC class I pathway, such as the VP22 protein from herpes simples virus and related herpes viruses.[0003]2. Description of the Background Art[0004]Naked DNA vaccines have emerged as attractive approaches for vaccine development (for review, see (1-3)). Intradermal administration of DNA vaccines via gene gun represents a convenient way of delivering DNA vaccines into professional antigen presenting cells (APCs) in vivo. Professional APCs are a superior candidate for ...

AI Technical Summary

Benefits of technology

[0010]The potency of naked DNA vaccines is limited by their inability to amplify and spread in vivo. VP22, a herpes simplex virus type 1 (HSV-1) protein and its “homologues” in other herpes viruses, such as the avian Marek's Disease Virus (MDV) have the property of intercellular transport that provide an approach for enhancing vaccine potency. The present inventors created novel fusions of VP22 with a model antigen, human papillomavirus type 16 (HPV-16) E7, in a DNA vaccine which generated enhanced spreading and MHC class I presentation of antigen. These properties led to a dramatic increase in the number of E7-specific CD8+ T cell precursors in vaccinated mice (at least 50-fold) and converted a less effective DNA vaccine into one with significant potency against E7-expressing tumors. In comparison, a non-spreading mutant, VP22(1-267), failed to enhance vaccine potency. Results presented in the Examples show that the potency of DNA vaccines is dramatically improved through enhanced intercellular spreading and MHC class I presentation of the antigen.

[0011]A similar study linking MDV-1 UL49 to E7 also led to a dramatic increase in the number of E7-specific CD8+ T cell precursors and potency response against E7 expressing tumors in vaccinated mice. Mice vaccinated with a MDV-1 UL49 DNA vaccine stimulated E7-specific CD8+ T cell precursor at a level comparable to that induced by HSV-1 VP22 / E7. Thus, fusion of MDV-1UL49 DNA to DNA encoding a target antigen gene significantly enhances the DNA vaccine potency.

[0012]The present invention is also directed to RNA replicon vaccine vaccines, preferably one based on a Sindbis virus RNA replicon. The present inventors tested E7 in the context of such a vaccine and showed (see Examples) that a Sindbis virus RNA vaccine encoding HSV-1 VP22 linked to E7 significantly increased activation of E7-specific CD8 T cells, resulting in potent antitumor immunity against E7-expressing tumors.

[0047](2) the antigen comprises an epitope that binds to, and is presented on the cell surface by, MHC class I proteins, thereby increasing the numbers or activity of the CTLs.

Problems solved by technology

The potency of naked DNA vaccines is limited by their inability to amplify and spread in vivo.

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