The antimicrobial peptide MetchnikowinII enhances Ptfa antigen immune responses against avian Pasteurella multocida
Niu Mingfu1, Gong Qiang1, Li Yang1
1Henan University of Science and Technology, Luoyang, China.
Abstract:
Immunostimulants and vaccines are the main means for controlling infectious diseases and searching highly effective and low toxic immunestimulants has always been the focus of researchers. The MetchnikowinII (MetII) had been expressed by us and exhibited both antibacterial and antifungal activities, in this study, we evaluated its potential for an adjuvant effect. In chickens, antigen-specific immunoglobulin Gs (IgGs) were increased after MetII adjuvanted vaccination using the Ptfa protein. Compared to group Ptfa + iFA, which was only adjuvanted with incomplete Freund's adjuvant (iFA), the antibody titers of the group Ptfa + iFA + Met20 μg·mL-1 (PFM20) and Ptfa + iFA + Propolis (PFP) significantly increased (P<0.05). Likewise, Interleukin-2 (IL-2) and Interferon-γ (IFN-γ) cytokines in group Ptfa + iFA + Met20 μg·mL-1 (PFM20) and Ptfa + iFA + Propolis (PFP) were significantly higher than those of the other three experimental groups (P<0.05). The stimulation index (SI) value in chickens of group PFM20 was significantly higher than that of the other four experimental groups (P<0.05). Chickens that received MetII adjuvanted vaccinations benefitted from higher protection rate (88%) when challenged with Pasteurella multocida (P. multocida), which was significantly higher than those of group PF and PFP (P<0.05). These results suggested that the antimicrobial peptide MetII may play an adjuvant role in the immune response in chickens but need a proper usage, because the higher usage of 40 μg·mL-1 and 60 μg·mL-1 resulted poor effect. Whether MetII could be a potential adjuvant or a biomolecule as part of a complex adjuvant for vaccines needs more experimental evidence, the study still provides an examples for understanding vaccine adjuvants.
Insights
The antimicrobial peptide MetchnikowinII (MetII) shows potential as a vaccine adjuvant in chickens, enhancing antibody and cytokine responses. Optimal dosage is crucial, as higher concentrations yielded reduced efficacy against Pasteurella multocida.
Area of Science:
- Veterinary Immunology
- Antimicrobial Peptides
- Vaccine Adjuvants
Background:
- Controlling infectious diseases relies on effective immunostimulants and vaccines.
- MetchnikowinII (MetII), a previously identified antimicrobial peptide, demonstrated antibacterial and antifungal properties.
- Research is ongoing to find highly effective, low-toxicity immunostimulants for vaccine development.
Purpose of the Study:
- To evaluate the adjuvant potential of MetchnikowinII (MetII) in chicken vaccination.
- To assess the impact of MetII on immune responses, including antibody titers and cytokine production.
- To determine the protective efficacy of MetII-adjuvanted vaccines against Pasteurella multocida challenge.
Main Methods:
- Chickens were vaccinated with the Ptfa protein, with or without MetII or incomplete Freund's adjuvant (iFA).
- Humoral and cellular immune responses were measured, including antigen-specific immunoglobulin G (IgG) titers, Interleukin-2 (IL-2), and Interferon-γ (IFN-γ) cytokine levels.
- Chickens were challenged with Pasteurella multocida to evaluate vaccine efficacy and protection rates.
Main Results:
- MetII-adjuvanted vaccination (20 μg·mL⁻¹) significantly increased antibody titers and cytokine levels (IL-2, IFN-γ) compared to controls.
- The MetII-adjuvanted group showed a significantly higher stimulation index (SI) value.
- Vaccination with MetII resulted in an 88% protection rate against Pasteurella multocida challenge, significantly higher than other groups.
- Higher concentrations of MetII (40 μg·mL⁻¹ and 60 μg·mL⁻¹) led to diminished efficacy.
Conclusions:
- The antimicrobial peptide MetII demonstrates significant adjuvant properties, enhancing immune responses in chickens.
- Optimal dosage of MetII is critical for effective adjuvant activity; higher doses may be detrimental.
- MetII shows promise as a potential adjuvant or component of complex adjuvants for vaccines, warranting further investigation.
