Six ferritin nanoparticles carrying potential antigen candidates of African swine fever virus induces robust humoral and cellular immune responses in pigs

Inadequate characterization of protective antigens poses a significant challenge in the development of vaccines for African swine fever (ASF), particularly for antigen-dependent formulations such as subunit, mRNA, and recombinant viral vector vaccines. In this study, we identified and evaluated six antigens of African swine fever virus (ASFV), the causative agent of ASF, namely p30, p54, E120R, H124R, E184L, and CD2v with potential protective capacities. Antibodies derived from pigs that were generated against p30, p54, E120R, H124R, and E184L after immunization demonstrated a significant capacity to inhibit viral replication in primary porcine alveolar macrophages (PAMs), whereas antibodies against CD2v specifically obstructed the hemadsorption of ASFV. Based on the six antigens mentioned above, we engineered antigen-conjugated ferritin nanoparticles using the SpyTag/SpyCatcher system to enhance the immunogenicity of antigen candidates. Notably, immunizing pigs with a mixture of nanoparticles, as opposed to using monomers with mixed antigens, resulted in an enhanced ability of antibodies to inhibit ASFV, with inhibition rates reaching 70.9% in PAMs. Regarding cellular immunity, the production of characterized by elevated serum IFN-γ levels, increased ASFV-specific IFN-γ-secreting effector cells, and higher CD8+ T cell proportions in pigs of nanoparticle mixed immunization. This study identifies potential antigen candidates and delivery strategies that elicit robust humoral and cellular immune responses for the development of a novel vaccine against ASFV.