Background: Porcine circovirus and Mycoplasma hyopneumoniae can cause respiratory
diseases in pigs, which cause serious economic loss in the worldwide pig industry. Currently, these
infections are mainly prevented and controlled by vaccination. The new vaccines on the market are
mainly composed of subunits and inactivated vaccines but usually have lower antigenicity than
traditional live vaccines. Thus, there is an increasing need to develop new adjuvants that can cause
rapid and long-lasting immunity to enhance the antigenic efficacy for vaccines. Studies have shown
that meningococcal porin PorB can act as a ligand to combine with Toll-like receptors to activate
the production of immunological projections and act as a vaccine immunological adjuvant.
Objective: In this article, we expressed and purified the recombinant PorB protein and verified its
immunogenicity against porcine circovirus type 2 and Mycoplasma hyopneumoniae genetically
Methods: In this article, we used prokaryotic expression to express and purify recombinant PorB
protein, four different concentrations of PorB protein, Freund's adjuvant with two genetically
engineered vaccines were combined with subcutaneous immunization of mice.
Results: Our study shows that the appropriate dose of the recombinant protein PorB can enhance
the levels of humoral and cellular responses induced by two genetically engineered vaccines in a
short period of time in mice. The PorB adjuvant group may cause statistically higher antibody titers
for both genetically engineered vaccines compared to Freund's commercial adjuvant (P<0.001).
Conclusion: The recombinant protein PorB may be a good candidate adjuvant for improving the
protective effect of vaccines against porcine circovirus type 2 and Mycoplasma hyopneumoniae,
and the protein can be used for future practical applications.