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Volume 6 Supplement 3

AIDS Vaccine 2009

OA021-03. Design and development of DNA vaccines for the co-expression of micro-RNA and HIV-1 Env

Background

Small non-coding micro-RNAs (miRNA) are important post-transcriptional regulators of mammalian gene expression. More recently, miRNAs have been described that regulate key elements of the adaptive immune response, such as T-cell development and activation (miR-181) and antigen presentation and development in B-cells (miR-155. miR-150), and various aspects of innate immunity (miR-146). We examined whether DNA vaccine vectors co-expressing miRNA with Env antigen could influence the magnitude or quality of the immune responses to Env in mice.

Methods

Human miR-155 and flanking regions from the non-protein encoding gene microRNA host gene 2 (MIRHG2), were introduced into an artifical intron within an envelope expression vector. Expression of miR-155 and Env was examined by Northern and Western Blot respectively. Using miR-155 sequences as a scaffold, we incorporated novel miRNAs encoded to silence expression of host antiviral proteins, or alternatively, to mimic other endogenous, immunomodulatory miRNAs.

Results

The human miR-155 was efficiently expressed and correctly processed from an upstream intron within an Env-expressing DNA vaccine plasmid in human cell lines. Locating the miRNA expression sequences within the intron did not reduce Env expression. Substitution of the native miR-155 guide sequence enabled the targeting of exogenous marker genes, EGFP and ds-Red. Targeting of cellular genes thought to influence Env expression in vivo, such as PKR and SFRS1, significantly down-modulated expression of targeted genes but failed to increase Env expression in vitro. In an alternative strategy, vaccine vectors delivering immunomodulatory miRNAs such as miR-155 were used to vaccinate BALB/c mice and the generation of Env-specific T-cells and effective antibody responses was measured.

Conclusion

This study provides evidence that native and engineered miRNAs can be successfully co-expressed with HIV-1 Env antigens. The further characterisation of immunomodulatory miRNAs may enable the development of vaccine vectors better able to shape the immune responses to HIV-1 vaccines towards protective correlates of immunity.

Author information

Correspondence to AK Wheatley.

Rights and permissions

Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Keywords

  • Vaccine Vector
  • Guide Sequence
  • Mammalian Gene Expression
  • Exogenous Marker
  • Upstream Intron