Cytokine expression in chicken embryo fibroblasts in response to infection with virulent or lentogenic avian avulavirus 1 (AAvV-1).

To investigate cytokine expression in chicken embryo fibroblast (CEF) cells, a virulent avian avulavirus 1 (AAvV-1) strain called SG10 that rapidly causes 100% mortality in its host, and a vaccine strain (La Sota) were characterized. Real-time quantitative PCR was performed on RNA samples from CEF cells, which were collected at 0, 24, 48 and 72 h post-infection. The dynamic expression patterns of ten cytokines (TNF-α, IFN-α, IFN-β, IL-1β, IL-2, IL-6, IL-10, IL-13, IL-15 and IL-18) were investigated. The results showed that infection with lentogenic La Sota induced significantly higher levels of the antiviral cytokines IFN-α and IFN-β, proinflammatory cytokines IL-2, IL-15 and IL-18, and the anti-inflammatory cytokine IL-10, than did infection with virulent SG10. Furthermore, the SG10 strain induced dramatically higher levels of the inflammatory cytokine IL-6 than those observed in cells infected with La Sota. However, the expression patterns of the other cytokines that were tested did not show any obvious trends or statistically significant differences between cells infected with the virulent and avirulent strains. These data show that infection with lentogenic La Sota induced more effective immune responses and anti-viral effects than did infection with virulent SG10 in CEFs. Our data provide distinct expression patterns of IFNs and proinflammatory and anti-inflammatory cytokines to AAvV-1 by virulence in CEF cells.