Toward a Pan-Arenavirus T-cell Vaccine: Identification and Preclinical Evaluation of Conserved Epitope constructs

Introduction/Rationale: Arenaviruses represent a rapidly expanding group of rodent-borne emerging human pathogens with significant pandemic potential. Diseases caused by these viruses, such as the Old-World Arenavirus (OWA) Lassa virus (LASV), which causes Lassa Fever, and the New-World Arenavirus (NWA) Junin virus (JUNV), which causes hemorrhagic fevers, currently lack effective therapeutics or vaccines. Members of the Arenaviridae family possess bi- or tri-segmented genomes encoding three to four viral proteins: glycoprotein (GP), nucleoprotein (NP), RNA polymerase (L) and matrix protein (Z). A robust T-cell immune response is critical for viral clearance and for limiting disease severity during the early stages of the infection.

Methods: Using a primary in vitro immunogenicity assay, we identified Conserved T cell Epitope Regions (CTERs) derived from conserved sequences within OWA and NWA, using LASV and JUNV as respective prototypes. These CTER epitopes were strongly recognized by human CD4+ T cells in vitro and were predicted to provide broad population coverage across diverse ethnicities. CTER constructs were designed based on the number of viral proteins included (GP+N+L, N+L, or L) and were assembled using AlphaFold into stable and unstable forms. Plasmids for OWA and NWA were codon-optimized and subsequently packaged into mRNA constructs.

Results: Our ongoing BDF1 mouse studies demonstrate that the CTER-based T-cell vaccine is both safe and immunogenic, as assessed using a combined activation-induced marker (AIM) and intracellular cytokine (ICS) assay. AIM+ T cells isolated from the spleen and lymph nodes show strong cross-reactive potential across the Arenaviridae family.

Conclusion: With further in vitro and in vivo evaluation, this work represents an initial step toward the development of a pan-arenavirus T-cell vaccine.