Chicken galectin-1B inhibits Newcastle disease virus adsorption and replication through binding to hemagglutinin-neuraminidase (HN) glycoprotein.

Galectin-1 is an important immunoregulatory factor and can mediate the host-pathogen interaction via binding glycans on the surface of various viruses. We previously reported that avian respiratory viruses, including lentogenic Newcastle disease virus (NDV), can induce up-regulation of chicken galectin (CG)-1B in the primary target organ. In this study, we investigated whether CG-1B participated in the infectious process of NDV in chickens. We demonstrated that velogenic NDV induced up-regulation of CG-1B in target organs. We also found that CG-1B directly bound to NDV virions and inhibited their hemagglutination activity in vitro We confirmed that CG-1B interacted with NDV hemagglutinin-neuraminidase (HN) glycoprotein, in which the specific G4 N-glycans significantly contributed to the interaction between CG-1B and HN glycoprotein. The presence of extracellular CG-1B, rather than the internalization process, inhibited adsorption of NDV. The interaction between intracellular CG-1B and NDV HN glycoproteins inhibited cell-surface expression of HN glycoprotein and reduced the titer of progeny virus in NDV-infected DF-1 cells. Significantly, the replication of parental and HN glycosylation mutant viruses in CG-1B knockdown and overexpression cells demonstrated that the replication of NDV was correlated with the expression of CG-1B in a specific glycan-dependent manner. Collectively, our results indicate that CG-1B has anti-NDV activity by binding to N-glycans on HN glycoprotein.

Induction of Avian ß-Defensin 2 Is Possibly Mediated by the p38 MAPK Signal Pathway in Chicken Embryo Fibroblasts After Newcastle Disease Virus Infection.

The study was conducted to evaluate whether avian ß-defensins (AvBDs) could be induced by Newcastle disease virus (NDV) infection, and to investigate the potential signaling pathway of AvBD2 induction in response to NDV infection as well. First, mRNA expression of AvBDs (1-14) was evaluated in the chicken embryo fibroblasts (CEFs) infected with NDV strain F48E9 at 6, 12, 24, 36, and 48 h post-inoculation (hpi), respectively. The results demonstrated a significant induction of AvBD2 in CEFs elicited by the NDV strain. Then, we expressed and purified the AvBD2 proteins in both eukaryotic cells and prokaryotic cells. Of the two recombinant AvBD2 proteins, only the protein expressed in eukaryotic cells showed directly antiviral activity against NDV strain F48E9 in vitro. Ligands of toll-like receptors (TLRs) were chosen as alternatives to NDV to further study signaling pathway of AvBD2 induction here, due to insufficient upregulation of AvBD2 expression elicited by NDV. We found that the mRNA expression of AvBD2 was highly upregulated by Pam3CSK4, FLA-ST, and ODN-M362. Then, four inhibitors of signaling pathway, including inhibitors of JNK, ERK1/2, p38 MAPK, and NF-κB, were used in this study. Of the four inhibitors, only inhibition of the p38 MAPK signaling pathway significantly reduced AvBD2 expression after stimulation with Pam3CSK4, FLA-ST and ODN-M362, respectively. Taken together, these results revealed that AvBD2 play a pivotal role in host innate immunity response to NDV infection. The mRNA expression of AvBD2 might be regulated in a p38 MAPK-dependent manner.

Recombinant Newcastle disease virus expressing the infectious bronchitis virus S1 gene protects chickens against Newcastle disease virus and infectious bronchitis virus challenge.

The recombinant LaSota strain expressing a chimeric IBV S1 gene (rLaSota-S1) was constructed with the S1 gene of the LX4 type IBV ck/CH/LDL/091022. The expression of the S1 protein was detected by an indirect immunofluorescence assay and Western blotting. The rLaSota-S1 strain was slightly attenuated, and its growth dynamics were similar to that of the parental LaSota strain. Vaccination of specific pathogen-free chickens with the rLaSota-S1 strain induced NDV hemagglutination inhibition antibodies, and it protected chickens from challenge with virulent NDV. In addition, vaccination with the rLaSota-S1 strain induced IBV-specific IgG antibodies and cellular immunity; however, a single vaccination provided partial protection with reduced virus shedding. Better protection efficiency was observed after a booster vaccination, which resulted in higher antibody titers, significantly fewer disease symptoms, and reduced virus replication and shedding. Our results suggest that the rLaSota-S1 strain is a bivalent vaccine candidate against both NDV and IBV.

Infection of Goose with Genotype VIId Newcastle Disease Virus of Goose Origin Elicits Strong Immune Responses at Early Stage.

Newcastle disease (ND), caused by virulent strains of Newcastle disease virus (NDV), is a highly contagious disease of birds that is responsible for heavy economic losses for the poultry industry worldwide. However, little is known about host-virus interactions in waterfowl, goose. In this study, we aim to characterize the host immune response in goose, based on the previous reports on the host response to NDV in chickens. Here, we evaluated viral replication and mRNA expression of 27 immune-related genes in 10 tissues of geese challenged with a genotype VIId NDV strain of goose origin (go/CH/LHLJ/1/06). The virus showed early replication, especially in digestive and immune tissues. The expression profiles showed up-regulation of Toll-like receptor (TLR)1-3, 5, 7, and 15, avian ß-defensin (AvBD) 5-7, 10, 12, and 16, cytokines [interleukin (IL)-8, IL-18, IL-1ß, and interferon-γ], inducible NO synthase (iNOS), and MHC class I in some tissues of geese in response to NDV. In contrast, NDV infection suppressed expression of AvBD1 in cecal tonsil of geese. Moreover, we observed a highly positive correlation between viral replication and host mRNA expressions of TLR1-5 and 7, AvBD4-6, 10, and 12, all the cytokines measured, MHC class I, FAS ligand, and iNOS, mainly at 72 h post-infection. Taken together, these results demonstrated that NDV infection induces strong innate immune responses and intense inflammatory responses at early stage in goose which may associate with the viral pathogenesis.