Comparative analysis of early immune responses induced by two strains of Newcastle disease virus in chickens

Abstract

Newcastle disease, caused by virulent strain of Newcastle disease virus (NDV), is an acute, highly contagious disease that is prevalent worldwide and is responsible for serious economic losses to the poultry industry. In the current study, we compared the early immune responses in chickens infected with two strains of velogenic NDV, a duck origin, named GD strain (Md/CH/LGD/1/2005, genotype VIId), and an chicken origin, F48E9 strain (genotype IX). The viral RNA level of GD strain was significantly higher than those of F48E9 in most tissues of chicken. Furthermore, the high level of viral RNA of the GD strain was associated with a stronger immune response compared to that of F48E9, characterized by upregulated expression of some of avian β-defensins and cytokines, most of toll-like receptors, and some of the other immune-related genes investigated. This study thus demonstrated differences in host early immune responses to the two NDV strains. Further studies are needed to characterize the basic molecular mechanisms involved in the host responses in chickens infected by the two NDV strains.

Pathologic Mechanisms of the Newcastle Disease Virus

“…Meanwhile, the geese-origin genotype VII virulent go/CH/LHLJ/1/06 strain did not stimulate IL-6 expression in geese [45]. The genotype VII virulent GD strain elevated IL-6 mRNA levels in the lung and Harderian gland of one-day-old SPF chickens at 48 h after infection [44]. However, the velogenic strain F48E9 only increased IL-6 expression slightly both in the CEFs and BF of SPF chickens, and the lentogenic LaSota strain did not alter IL-6 levels [43,47,50].…”

“…Compared with the F48E9 strain, the genotype VIId GD strain induced a fiercely robust IFN-γ expression in the spleen at 48 h, but other cytokines such as IL-6, AvBD2, and AvBD3 did not significantly change. As for other tissues, in the lung and Harderian glands, IFN-γ, IL-6, iNOS, AvBDs, TLRs, and MHCII were expressed at significantly higher levels in chickens challenged with the GD strain rather than with the viruses of the F48E9 strain group [44]. Additionally, the genotype VIId go/CH/LHLJ/1/06 strain is also an efficient stimulator of IFN-γ in geese, which is accompanied by an intense innate immune response [45].…”

Pathogenicity and innate immune responses induced by fowl adenovirus serotype 8b in specific pathogen-free chicken

“…For example, AvBDs exhibited antiviral activities against PPMV ( Li et al, 2015 ) and infectious bronchitis virus ( Xu et al, 2015 ). Meanwhile, AvBDs expression was upregulated in chickens’ tissues following infection with these viruses, as well ( Ikezawa et al, 2012 ; Li et al, 2015 ; Zhang et al, 2019 ). Besides, host defense peptides have been shown to exhibit strong adjuvant potential ( Sarfraz et al, 2017 ).…”

“…At each time point, total RNA was extracted from tissue samples using TRIzol reagent (Invitrogen, Beijing, PR China) according to the manufacturer's protocol. The mRNA expression levels of the target genes were measured using One-step Real-time PrimeScript RT-PCR (Takara Biotechnology, Dalian, China) with specific primers, as described previously ( Li et al, 2015 ; Xu et al, 2016 ; Zhang et al, 2019 ). The mRNA levels of the selected genes were quantified by using standard curves generated by a serial dilution of plasmids as described previously ( Zhang et al, 2019 ).…”