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Immuno-stimulatory class I-restricted cytotoxic T lymphocytes (CTL) epitopes of porcine reproductive and respiratory syndrome virus (PRRSV) are important for vaccine development. In this study we first determined the expression frequency of swine leukocyte antigen (SLA) class I alleles in commercial pigs in the United States. The SLA genotyping result allowed us to predict potential CTL epitopes from a contemporary strain of PRRSV (RFLP 1-7-4) by using bioinformatic tools. The predicted epitopes were then evaluated in an ex vivo stimulation assay with peripheral blood mononuclear cells isolated from pigs experimentally-infected with PRRSV. Using flow-cytometry analysis, we identified a number of immuno-stimulatory CTL epitopes, including two peptides from GP3 and two from Nsp9 that significantly improved both degranulation marker CD107a and IFN-γ production in cytotoxic CD4+CD8+ T cells, CD8+ T cells, and γδ T cells, and two peptides that inhibited IFN-γ production. These CTL epitopes will aid future vaccine development against PRRSV. [ABSTRACT FROM AUTHOR]

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated disease (PCVAD). Available commercial vaccines all target PCV2a subtype, although the circulating predominant subtype worldwide is PCV2b, and the emerging PCV2d subtype is also increasingly associated with PCVAD. Here we molecularly bred genetically-divergent strains representing PCV2a, PCV2b, PCV2c, PCV2d, and “divergent PCV2a” subtypes by DNA-shuffling of the capsid genes to produce a chimeric virus representing PCV2 global genetic diversity. When placed in the PCV2a backbone, one chimeric virus (PCV2-3cl14) induced higher neutralizing antibody titers against different PCV2 subtypes. Subsequently, a candidate vaccine (PCV1-3cl14) was produced by cloning the shuffled 3cl14 capsid into the backbone of the non-pathogenic PCV1. A vaccine efficacy study revealed that chimeric virus PCV1-3cl14 induces protective immunity against challenge with PCV2b or PCV2d in pigs. The chimeric PCV1-3cl14 virus is a strong candidate for a novel vaccine in pigs infected with variable PCV2 strains. [ABSTRACT FROM AUTHOR]