Pro-inflammatory cytokine and apoptotic gene mRNA levels against lentogenic and velogenic Newcastle disease virus pathotypes in in-vivo and in-vitro biological systems

Abstract

Knowledge on the influence of pro-inflammatory cytokine and apoptotic gene mRNA levels in the pathogenesis of Indian field isolates of Newcastle disease virus (NDV) is little. In this study, cytokine mRNA levels were elucidated in spleen of chickens (in-vivo) and chicken embryo fibroblast cells (in-vitro) infected with lentogenic D58 strain and viscerotropic velogenic D165 isolate until five days post infection (dpi). In spleen of chickens infected with D165, maximum upregulation of pro-inflammatory cytokines (IL-1b, IL-6, TNF-a), chemokine (IL-8) and apoptotic gene (Caspase-8) at 3dpi correlated with the onset of severe clinical signs and necrotic histopathological lesions in spleen, proventriculus, intestine and caecal tonsil of chickens. Similarly, in CEF cells infected with D165, upregulation of pro-inflammatory cytokine and apoptotic gene mRNA levels correlated with the appearance of CPE. In spleen of chickens and CEF cells infected with D58, there was comparatively minimal upregulation of pro-inflammatory cytokine and apoptotic gene mRNA levels which did not cause histopathological changes in tissues and CPE formation in CEF cells. In both in-vivo and in-vitro systems, upregulation of anti-inflammatory cytokine IL-10 showed inhibitory effects on the mRNA levels of pro-inflammatory cytokines. Thus, this study reports variation in the cytokine mRNA levels elucidated in response to two different pathotypes isolated from India and associates the same with the clinical signs and pathological lesions produced during the course of ND.