Interferon-gamma response of PBMC indicates productive pseudorabies virus (PRV) infection in swine

In Chinese Meishan/German Landrace cross-bred swine F(2) generation interferon gamma (IFN-γ) production by peripheral blood mononuclear cells (PBMC) was determined directly ex vivo at different time points after survival of a virulent pseudorabies virus (PRV) infection. This reactivity was compared with the reactivity of naïve PBMC. Significant IFN-γ production was determined in ELISA and ELISPOT only after in vitro PBMC re-stimulation with PRV and not with the closely related bovine herpesvirus BHV-1. The PRV-specific IFN-γ secretion from re-stimulated PBMC showed high levels 6 days after infection, before the presence of serum antibodies, and it persisted at a high level over a 3 months period. The response of a group of eight piglets infected intranasally with PRV varied. Only two animals showed the expected typical fever response. PRV specific IFN-γ production by PBMC clearly indicated that infection had occurred. Early significant IFN-γ production by primed PBMC turned out to be a reliable and specific ex vivo marker for cellular response against productive PRV infection in swine before antibody formation.