Recombinant adenovirus expressing type Asia1 foot-and-mouth disease virus capsid proteins induces protective immunity against homologous virus challenge in mice

Foot-and-mouth disease (FMD) is a highly contagious disease worldwide affecting cloven-hoofed animals that is caused by foot-and-mouth disease virus (FMDV). The FMDV capsid polyprotein and 3C proteinase are required for capsid precursor processing and assembly. The FMDV capsid protein, which contains the entire repertoire of immunogenic sites, can stimulate both humoral immunity and T-cell-mediated immune responses. In this study, we constructed a recombinant adenovirus, rAdV-Asi-05, that expresses the P1-2A and 3C genes of the type Asia1 FMDV strain Asia1/YS/CHA/05. The humoral immune responses elicited by the Ad5-vectored capsid protein of type Asia1 FMDV in BALB/c mice and the ability of rAdV-Asi-05 to rapidly induce protection against challenge with FMDV Asia1/YS/CHA/05 in C57BL/6 mice were evaluated. The processing of polyprotein P1 into the structural proteins VP0, VP3, and VP1 in rAdV-Asi-05-infected HEK 293 cells was detected by Western blotting. BALB/c mice immunised with rAdV-Asi-05 produced type Asia1 FMDV-specific neutralising antibodies, and the neutralisation titres increased significantly after the boost. Importantly, C57BL/6 mice immunised with a single 107 PFU dose of rAdV-Asi-05 exhibited protective immunity against challenge with 100 times the lethal dose of FMDV Asia1/YS/CHA/05. In summary, rAdV-Asi-05 elicited a high titre of neutralising antibodies against type Asia1 FMDV in BALB/c mice. Moreover, rAdV-Asi-05 provided complete protection against FMDV Asia1/YS/CHA/05 challenge in C57BL/6 mice. This study highlights the potential of rAdV-Asi-05 to serve as a type Asia1 FMDV vaccine.