Immune responses of multi-epitope recombinant vaccine candidate strains against Fusobacterium nucleatum in mice

Fusobacterium nucleatum (F. nucleatum) harbors multiple virulence-associated factors, notably Fap2, FomA, and FadA, which collectively mediate its pathogenic potential through diverse mechanisms including host cell adhesion, tissue invasion, and immunomodulatory interactions.

This study was designed to construct and characterize recombinant vaccine candidates expressing multi-epitope antigens derived from these three virulence factors, followed by evaluation of their capacity to induce specific immune responses against F. nucleatum.

Computational prediction and screening of antigenic epitopes from Fap2, FomA, and FadA using the SVMTriP algorithm; Individual ligation of three synthesized multi-epitope-encoding sequences into the pGEX-1λT expression vector (with empty vector as negative control); Successful transformation of recombinant plasmids into Escherichia coli BL21 (DE3) competent cells; Expression analysis of recombinant multi-epitope proteins; Quantitative assessment of serum antigen-specific IgA and IgG levels in immunized C57BL/6 mice.

Molecular confirmation of recombinant strains through comprehensive validation including PCR amplification, restriction enzyme digestion, and DNA sequencing. Differential immune responses observed: Fap2-and FadA-based constructs preferentially stimulated IgA production, FomA-derived antigen predominantly elicited IgG responses.

We have successfully developed and verified recombinant vaccine strains expressing multi-epitope antigens from F. nucleatum virulence factors Fap2, FomA, and FadA. These constructs demonstrated the capacity to provoke distinct antigen-specific antibody responses in mice, highlighting their promising potential as vaccine candidates against F. nucleatum infections.