Abstract
BackgroundPorcine 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.MethodsChitosan 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.ResultsFeeding 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.ConclusionChitosan 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.
Highlights
Porcine circovirus type 2 (PCV2)-associated diseases are a major problem for the swine industry worldwide
These diseases are known as Porcine circovirus-associated diseases (PCVAD) or PCV2-associated diseases, a name that the American Association of Swine Veterinarians (AASV) uses to group together all diseases attributed to PCV2, including post-weaning multisystemic wasting syndrome (PMWS) [4]
Encapsulating the PCV2 cap protein into chitosan microparticles Crude yeast extracts containing approximately 10% p/p PCV2 virus-like particles (VLPs) were encapsulated with low molecular weight (LMW) chitosan, which improves both permeability and stability
Summary
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. PCV2 is associated with many other conditions, including respiratory disease complex, reproductive failure, porcine dermatopathy and nephropathy syndrome (PDNS), congenital tremor, necrotizing tracheitis, and exudative epidermitis [3]. These diseases are known as PCVAD or PCV2-associated diseases, a name that the American Association of Swine Veterinarians (AASV) uses to group together all diseases attributed to PCV2, including PMWS [4]. In addition to improved management and husbandry (e.g., better hygiene, less overcrowding, and better ventilation), anti-PCV2 vaccines are an efficient method of reducing both the impact of the disease and the subsequent economic costs; the worldwide demand for anti-PCV2 vaccines is high [5]
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