Research Project 2: Antigen design and immunological evaluation

In Project 2 (P2) we will use cutting-edge antigen engineering to refine vaccine antigen design strategies through iterative assessments of immunogenicity and protective efficacy to generate optimized vaccine immunogens against nairo-, hanta-, and paramyxoviruses. Our approach will establish a protective antigen engineering

blueprint for emerging bunyaviruses and paramyxoviruses with pandemic potential. We will interact with the other PROVIDENT projects and cores for antigen production (CC), animal efficacy testing (CD), mRNA vaccines (P3, CE), and sharing knowledge and resources (CB, P1, P3, P4). Aim P2.1: Structure-based antigen design. We

will utilize an in-depth understanding of structural biology of viral surface proteins to design and express recombinant viral antigens from a prototype nairovirus (Crimean-Congo hemorrhagic fever virus, CCHFV), hantavirus (Andes virus, ANDV), and paramyxovirus (Menangle virus). Following optimization of antigen designs

for prototype viruses, design strategies will be applied to related but genetically distant outgroup viruses (nairoviruses: Hazara virus; hantaviruses: Sin Nombre virus and Hantaan virus; paramyxoviruses: Sosuga virus and Nipah virus) to validate that our vaccine design approach is applicable within virus families. Aim P2.2:

Antigenicity and protective efficacy of engineered antigens. We will vaccinate animals with recombinant antigens designed in P2.1 and produced by CC and evaluate immunogenicity and in vivo efficacy against viral infection. Following down-selection, lead antigens will be incorporated into mRNA vaccine platforms optimized by P3.

Comparative immunogenicity and in vivo efficacy studies will evaluate recombinant- and mRNA-based vaccine platforms head-to-head. Based on results obtained using prototype viruses from each family, we will apply antigen design strategies to outgroup viruses and evaluate immunogenicity and protective efficacy of lead

candidates in existing and/or novel animal models being developed by CD. Aim P2.3: Characterization of humoral immune responses to engineered antigens. We will evaluate humoral immune responses to engineered antigens using samples collected from animal studies (P2.2) using high-throughput, well-characterized assays.

We will use authentic and surrogate virus assays to rapidly evaluate neutralization potential and Fc-mediated activity of vaccine-elicited polyclonal antibodies. VH-VL antibody repertoires encoded by peripheral B cell subsets will be identified using novel multivalent BCR-seq methodologies. We will also investigate correlates of

protection for lead CCHFV and ANDV vaccine antigens from P2.2 by executing B cell depletion studies with support from CD. Aim P2.4: Evaluations of T cell responses to engineered antigens. We will perform in-depth analyses of peripheral, tissue resident, and follicular memory T cell responses in vaccinated animals and will

conduct T cell receptor sequencing to identify the breadth and diversity of T cell responses post-vaccination. To assess the role of T cells in protective efficacy, T cell depletion studies will be completed with support from CD. This project will provide a roadmap to optimize vaccine immunogens for nairo-, hanta-, and paramyxoviruses.