Browsing by Author "Samudh, Nazia"

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    Characterisation of the murine immune response to self-amplifying mRNA sequences encoding Hepatitis B virus surface proteins
    (University of the Witwatersrand, Johannesburg, 2024) Samudh, Nazia; Bloom, Kristie
    Vaccination against Hepatitis B virus (HBV) remains the most effective means of preventing infection. However, approximately 10% of vaccinated individuals fail to develop neutralising antibodies necessitating the development of improved vaccines which target the more immunogenic large HBV surface antigen (L-HBsAg) and can elicit cell-mediated immunity. Although Africa bears a high burden of HBV infections, placing many individuals at risk of contracting the disease, we rely on imported vaccines for prophylactic vaccination programmes. The COVID-19 pandemic was a stark reminder of Africa’s vaccine dependence and since then great interest has been generated in establishing vaccine manufacturing capabilities on the African continent. Herein, we explored the Alphavirus-based self-amplifying RNA (saRNA) vaccine platform to produce dose-sparing HBV vaccines which could contribute to vaccine independence. saRNAs encoding reporter proteins, small HBV surface antigen (S-HBsAg) or L-HBsAg were synthesised by optimised in vitro transcription. Expression of reporter proteins from saRNAs was achieved even at low concentrations and was observed for extended periods of time in vitro. saRNAs encoding S-HBsAg were able to trigger the interferon response in a dose-response manner in vitro, however, this did not hamper antigen expression. Expression of L-HBsAg was achieved but restricted to the intracellular space and will require sequence modification to facilitate secretion. In vivo delivery of saRNAs by electroporation or commercially available cationic liposomes was found to be unsuccessful, and further optimisation of in vivo saRNA delivery is required before determining the prophylactic potential of candidate vaccines. This preliminary study has produced promising results demonstrating the dose-sparing properties and self-adjuvanting nature of the saRNA vaccine platform