Mildenberg, B. | Search bioRxiv

bioRxiv2026

Impact of RNA modification and IL-12 boosts on mRNA-LNP vaccine-elicited CD8+ T cell responses

Development of effective HIV-1 vaccines requires strategies for inducing both CD8+ T cell and neutralizing antibody responses. Nucleoside-modified mRNA-lipid-nanoparticles (LNP) induce more potent antibody responses than unmodified mRNA-LNP vaccines, while unmodified mRNA is typically employed for CD8+ T cell-inducing vaccines. Here, we compared the abilities of differing ratios of unmodified versus modified mRNA expressing a SIV conserved-region CD8+ T cell immunogen co-administered with IL-12-encoding mRNA-LNP during boosting to induce CD8+ T cell and humoral responses in non-human primates, assessing responses in ChAdOx1-primed controls in parallel. Serial priming and boosting with fully-unmodified mRNA elicited higher-magnitude, more CD8-biased T cell responses than fully-modified mRNA, that were durably maintained after the IL-12-encoding mRNA boosts. Inclusion of 30% nucleoside-modified mRNA enhanced antibody titers, suggesting potential benefits to a mixed-composition vaccine.

immunology↗

bioRxiv2020

Immunogenicity, safety and efficacy of sequential immunizations with an SIV-based IDLV expressing CH505 Envs

A preventative HIV-1 vaccine is an essential intervention needed to halt the HIV-1 pandemic. Neutralizing antibodies protect against HIV-1 infection in animal models, and thus an approach toward a protective HIV-1 vaccine is to induce broadly cross-reactive neutralizing antibodies (bnAbs). One strategy to achieve this goal is to define envelope (Env) evolution that drives bnAb development in infection and to recreate those events by vaccination. In this study we report the immunogenicity, safety and efficacy in rhesus macaques of an SIV-based integrase defective lentiviral vector (IDLV) expressing sequential gp140 Env immunogens derived from the CH505 HIV-1-infected individual who made the CH103 and CH235 bnAb lineages. Immunization with IDLV expressing sequential CH505 Env induced higher magnitude and more durable binding and neutralizing antibody responses compared to protein or DNA +/- protein immunizations using the same sequential envelopes. Compared to monkeys immunized with vector expressing Envs alone, those immunized with the combination of IDLV expressing Env and CH505 Env protein demonstrated improved durability of antibody responses at six month after the last immunization as well as lower peak viremia and better virus control following autologous SHIV-CH505 challenge. There was no evidence of vector mobilization or recombination in the immunized and challenged monkeys. Our results show that while IDLV proved safe and successful at inducing higher titer and more durable immune responses compared to other vaccine platforms, the use of non-stabilized sequential envelope trimers did not induce broadly neutralizing antibody responses.

immunology↗