Search

Porcine epidemic diarrhea virus (PEDV) first emerged in the United States in 2013 causing high mortality and morbidity in neonatal piglets with immense economic losses to the swine industry. PEDV is an alpha-coronavirus replicating primarily in porcine intestinal cells. PEDV vaccines are available in Asia and Europe, and conditionally-licensed vaccines recently became available in the United States but the efficacies of these vaccines in eliminating PEDV from swine populations are questionable. In this study, the immunogenicity of a subunit vaccine based on the spike protein of PEDV, which was directly targeted to porcine dendritic cells (DCs) expressing Langerin, was assessed. The PEDV S antigen was delivered to the dendritic cells through a single-chain antibody specific to Langerin and the targeted cells were stimulated with cholera toxin adjuvant. This approach, known as "dendritic cell targeting," greatly improved PEDV S antigen-specific T cell interferon-γ responses in the CD4 pos CD8 pos T cell compartment in pigs as early as 7days upon transdermal administration. When the vaccine protein was targeted to Langerin pos DCs systemically through intramuscular vaccination, it induced higher serum IgG and IgA responses in pigs, though these responses require a booster dose, and the magnitude of T cell responses were lower as compared to transdermal vaccination. We conclude that PEDV spike protein domains targeting Langerin-expressing dendritic cells significantly increased CD4 T cell immune responses in pigs. The results indicate that the immunogenicity of protein subunit vaccines can be greatly enhanced by direct targeting of the vaccine antigens to desirable dendritic cell subsets in pigs., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Porcine circovirus type-2b (PCV2b) is the primary global causative agent of porcine circovirus-associated disease (PCVAD). In this study, we first constructed a novel chimeric virus (PCV1-2b) with the PCV2b capsid gene cloned into the backbone of non-pathogenic PCV1. A pathogenicity study conducted in caesarean-derived colostrum-deprived pigs showed that pigs inoculated with PCV1-2b (n=10) had decreased lymphoid lesions and significantly lower viral load at 21 dpi, and significantly lower viremia starting at 14 dpi compared to pigs inoculated with PCV2b (n=10). All PCV1-2b infected pigs remained clinically healthy, while four of ten PCV2b-infected pigs died or were euthanized early due to clinical PCVAD. In a subsequent challenge study, conventional pigs were first vaccinated with PCV1-2b (n=20) or left unvaccinated (n=20), and 10 pigs in each group were then challenged with PCV2a and PCV2b, respectively. Vaccinated pigs had no detectable viremia and significantly decreased overall lymphoid lesion scores and lower viral loads compared to unvaccinated controls. The results indicate the chimeric PCV1-2b virus is a good candidate for a live-attenuated vaccine against both PCV2b and PCV2a subtypes., (Copyright © 2010 Elsevier Ltd. All rights reserved.)