Downregulation of IL-15 and IL-18 in chicken embryo fibroblasts in response to virulent or lentogenic Newcastle disease virus infection

Abstract

Newcastle disease virus (NDV) is an important pathogen hazardous to poultry industry, and the pathogenicity of NDV strains varies with different virulence. Chicken Embryo Fibroblasts can serve as a laboratory host systems for NDV, and cytopathic effects (CPE) has some relationship to the strain's virulence. In order to explore the rhythm of cytokine expression in CEF following velogenic or lentogenic strain infection, NDV virulent strain F48E9 and vaccine strain Lasota were used to infect CEF separately, and cells were collected at 0, 4, 8, 12, 24, 36 hours post-infection (h.p.i.). The total RNA was isolated and real-time quantitative RT-PCR was used to detect the expression of interleukin (IL)-15 and IL-18 gene. The results showed that the expression of both IL-15 and IL-18 gene of F48E9 and Lasota groups were significantly lower than the control group at 4 h, 8 h, 12 h, 24 h.p.i.. But at 36 h.p.i., the expression level of both IL-15 and IL-18 gene of F48E9 group increased rapidly to the level higher than that of control group, while in the Lasota group, the picture was quite different, the expression level of both IL-15 and IL-18 are still lower than that of the control group. The expression change of other cytokines showed no clear regularity in F48E9 or Lasota group. Expression of IL-15 and IL-18 may play an important role in mediation of NDV pathogenesis in CEF. © 2012 Springer-Verlag GmbH.