title: Chitosan microparticles loaded with yeast-derived PCV2 virus-like particles elicit antigen-specific cellular immune response in mice after oral administration.
abstract: BACKGROUND
  Porcine circovirus type 2 (PCV2)-associated diseases are a major problem for the swine industry worldwide. In addition to improved management and husbandry practices, the availability of several anti-PCV2 vaccines provides an efficient immunological option for reducing the impact of these diseases. Most anti-PCV2 vaccines are marketed as injectable formulations. Although these are effective, there are problems associated with the use of injectable products, including laborious and time-consuming procedures, the induction of inflammatory responses at the injection site, and treatment-associated stress to the animals. Oral vaccines represent an improvement in antigen delivery technology; they overcome the problems associated with injection management and facilitate antigen boosting when an animals' immunity falls outside the protective window.
  
  
  METHODS
  Chitosan microparticles were used as both a vehicle and mucosal adjuvant to deliver yeast-derived PCV2 virus-like particles (VLPs) in an attempt to develop an oral vaccine. The physical characteristics of the microparticles, including size, Zeta potential, and polydispersity, were examined along with the potential to induce PCV2-specific cellular immune responses in mice after oral delivery.
  
  
  RESULTS
  Feeding mice with PCV2 VLP-loaded, positively-charged chitosan microparticles with an average size of 2.5 μm induced the proliferation of PCV2-specific splenic CD4+/CD8+ lymphocytes and the subsequent production of IFN-γ to levels comparable with those induced by an injectable commercial formulation.
  
  
  CONCLUSIONS
  Chitosan microparticles appear to be a safe, simple system on which to base PCV2 oral vaccines. Oral chitosan-mediated antigen delivery is a novel strategy that efficiently induces anti-PCV2 cellular responses in a mouse model. Further studies in swine are warranted.
authors.affiliation: Centro Biotecnológico Veterinario, Biovetec, Departamento de Ciencias Biológicas Animales, Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, La Pintana, Santiago, Chile. sbucarey@uchile.cl.
authors.forename: Sergio A
authors.initials: SA
authors.lastname: Bucarey
authors.forename: Myriam
authors.initials: M
authors.lastname: Pujol
authors.forename: Joaquín
authors.initials: J
authors.lastname: Poblete
authors.forename: Ignacio
authors.initials: I
authors.lastname: Nuñez
authors.forename: Cecilia V
authors.initials: CV
authors.lastname: Tapia
authors.forename: Andrónico
authors.initials: A
authors.lastname: Neira-Carrillo
authors.forename: Jonatán
authors.initials: J
authors.lastname: Martinez
authors.forename: Oliver
authors.initials: O
authors.lastname: Bassa
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D000917:Antibody Formation / Q000276:immunology; D000956:Antigens, Viral / Q000737:chemistry / Q000276:immunology*; D036022:Capsid Proteins / Q000235:genetics / Q000276:immunology; D048271:Chitosan / Q000737:chemistry*; D018173:Circoviridae Infections / Q000517:prevention & control* / Q000821:virology; D017925:Circovirus / Q000145:classification* / Q000502:physiology*; D005786:Gene Expression Regulation / Q000276:immunology; D007111:Immunity, Cellular / Q000502:physiology*; D007371:Interferon-gamma; D051379:Mice; D008810:Mice, Inbred C57BL; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D036022:Capsid Proteins; D014765:Viral Vaccines; D007371:Interferon-gamma; D048271:Chitosan