Immunity Elicited by an Experimental Vaccine Based on Recombinant Flagellin-Porcine Circovirus Type 2 Cap Fusion Protein in Piglets

PLoS One. 2016 Feb 5;11(2):e0147432. doi: 10.1371/journal.pone.0147432. eCollection 2016.

Abstract

In a recent study, we reported that a recombinant protein from fusion expression of flagellin to porcine circovirus type 2 (PCV2) Cap induced robust humoral and cell-mediated immunity that afforded full protection for PCV2 infection using BALB/c mice. Here, we further evaluated the immunogenicity and protection of the recombinant protein using specific pathogen free (SPF) pigs. Twenty-five 3-week-old piglets without passively acquired immunity were divided into 5 groups. All piglets except negative controls were challenged with a virulent PCV2 at 21 days after booster vaccination and necropsied at 21 days post-challenge. Vaccination of piglets with the recombinant protein without adjuvant induced strong humoral and cellular immune responses as observed by high levels of PCV2-specific IgG antibodies and neutralizing antibodies, as well as frequencies of PCV2-specific IFN-γ-secreting cells that conferred good protection against PCV2 challenge, with significant reduced PCV2 viremia, mild lesions, low PCV2 antigen-positive cells, as well as improved body weight gain, comparable to piglets vaccinated with a commercial PCV2 subunit vaccine. These results further demonstrated that the recombinant flagellin-Cap fusion protein is capable of inducing solid protective humoral and cellular immunity when administered to pigs, thereby becoming an effective PCV2 vaccine candidate for control of PCV2 infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Neutralizing / blood
  • Antibodies, Neutralizing / immunology
  • Antibodies, Viral / blood
  • Antibodies, Viral / immunology
  • Capsid Proteins / genetics
  • Capsid Proteins / immunology*
  • Circovirus / genetics
  • Circovirus / immunology*
  • Disease Models, Animal
  • Flagellin / genetics
  • Flagellin / immunology*
  • Immunity, Cellular
  • Immunity, Humoral
  • Interferon-gamma / metabolism
  • Kinetics
  • Lymph Nodes / immunology
  • Lymph Nodes / pathology
  • Mice
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology*
  • Swine
  • Swine Diseases / diagnosis
  • Swine Diseases / prevention & control*
  • Swine Diseases / virology
  • Viral Load
  • Viral Vaccines / immunology*

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • Capsid Proteins
  • Recombinant Fusion Proteins
  • Viral Vaccines
  • Flagellin
  • Interferon-gamma

Grants and funding

This work was supported by grants from the National Science Fund for Distinguished Young Scholars (31025028) and the Beijing Municipal Science and Technology Contract Project (Z07010501780701), People’s Republic of China. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.