Enhanced immunogenicity following miR-155 incorporation into the influenza A virus genome

•Incorporation of miR-155 into the influenza A virus genome highlights the potential of this technology to create self-adjuvanting live vaccines.•miRNA-155 expression enhanced influenza-specific CD8+ T cell responses.•miRNA-155 expression enhanced influenza-specific antibody responses.

Influenza A vaccine efficacy in the elderly is generally poor and so identification of novel molecular adjuvants to improve immunogenicity is important to reduce the overall burden of disease. Short non-coding RNAs, known as microRNAs (miRNAs) are known to regulate gene expression and have the potential to influence immune responses. One such miRNA, miR-155, has been shown to modulate T and B cell development and function. We incorporated miR-155 into the influenza A virus (IAV) genome creating a self-adjuvanting 'live vaccine' with the ability to modify immunogenicity. Infection of mice with a recombinant influenza virus encoding miR-155 in the NS gene segment altered epitope-specific expansion of influenza-specific CD8+ T cells and induced significantly higher levels of neutralising antibody.

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