The W195 Residue of the Newcastle Disease Virus V Protein Is Critical for Multiple Aspects of Viral Self-Regulation through Interactions between V and Nucleoproteins.

The transcription and replication of the Newcastle disease virus (NDV) strictly rely on the viral ribonucleoprotein (RNP) complex, which is composed of viral NP, P, L and RNA. However, it is not known whether other viral non-RNP proteins participate in this process for viral self-regulation. In this study, we used a minigenome (MG) system to identify the regulatory role of the viral non-RNP proteins V, M, W, F and HN. Among them, V significantly reduced MG-encoded reporter activity compared with the other proteins and inhibited the synthesis of viral mRNA and cRNA. Further, V interacted with NP. A mutation in residue W195 of V diminished V-NP interaction and inhibited inclusion body (IB) formation in NP-P-L-cotransfected cells. Furthermore, a reverse-genetics system for the highly virulent strain F48E9 was established. The mutant rF48E9-VW195R increased viral replication and apparently enhanced IB formation. In vivo experiments demonstrated that rF48E9-VW195R decreased virulence and retarded time of death. Overall, the results indicate that the V-NP interaction of the W195 mutant V decreased, which regulated viral RNA synthesis, IB formation, viral replication and pathogenicity. This study provides insight into the self-regulation of non-RNP proteins in paramyxoviruses.

Cellular CARD11 Inhibits the Fusogenic Activity of Newcastle Disease Virus via CBM Signalosome-Mediated Furin Reduction in Chicken Fibroblasts.

Newcastle disease virus (NDV) causes an infectious disease that poses a major threat to poultry health. Our previous study identified a chicken brain-specific caspase recruitment domain-containing protein 11 (CARD11) that was upregulated in chicken neurons and inhibited NDV replication. This raises the question of whether CARD11 plays a role in inhibiting viruses in non-neural cells. Here, chicken fibroblasts were used as a non-neural cell model to investigate the role. CARD11 expression was not significantly upregulated by either velogenic or lentogenic NDV infection in chicken fibroblasts. Viral replication was decreased in DF-1 cells stably overexpressing CARD11, while viral growth was significantly increased in the CARD11-knockdown DF-1 cell line. Moreover, CARD11 colocalized with the viral P protein and aggregated around the fibroblast nucleus, suggesting that an interaction existed between CARD11 and the viral P protein; this interaction was further examined by suppressing viral RNA polymerase activity by using a minigenome assay. Viral replication was inhibited by CARD11 in fibroblasts, and this result was consistent with our previous report in chicken neurons. Importantly, CARD11 was observed to reduce the syncytia induced by either velogenic virus infection or viral haemagglutinin-neuraminidase (HN) and F cotransfection in fibroblasts. We found that CARD11 inhibited the expression of the host protease furin, which is essential for cleavage of the viral F protein to trigger fusogenic activity. Furthermore, the CARD11-Bcl10-MALT1 (CBM) signalosome was found to suppress furin expression, which resulted in a reduction in the cleavage efficiency of the viral F protein to further inhibit viral syncytia. Taken together, our findings mainly demonstrated a novel CARD11 inhibitory mechanism for viral fusogenic activity in chicken fibroblasts, and this mechanism explains the antiviral roles of this molecule in NDV pathogenesis.

Invariant set based distributed protocol for synchronization of discrete-time heterogeneous systems with nonlinear dynamics.

We in this paper propose an invariant set based distributed control protocol for synchronization of discrete-time heterogeneous multiagent systems. Starting with the assumption that the distributed control input will vanish once a multiagent system achieves synchronization, we attain an easily verifiable method for the nonexistence of synchronous trajectories through characterizing the vector fields of agents. Then, we introduce an invariant set to analyze the limit behaviors of all the synchronous trajectories. Afterwards, based on the assumption that the above invariant set can be characterized by the graph of a function, we design a distributed control protocol to transform the heterogeneous system into an equivalent one, which is composed of two lower dimensional systems. Moreover, for this equivalent system, we provide a synchronization criterion via constructing corresponding Lyapunov-type functions for these two lower dimensional systems, arriving at a synchronization criterion for the original heterogeneous system. Especially, we further improve the applicability of this synchronization criterion by using multiple Lyapunov-type functions. Finally, three examples are presented to demonstrate the validity of the corresponding theoretical results.

Synchronization of heterogeneous linear networks with distinct inner coupling matrices.

In this paper, we study synchronization of heterogeneous linear networks with distinct inner coupling matrices. Firstly, for synchronous networks, we show that any synchronous trajectory will converge to a corresponding synchronous state. Then, we provide an invariant set, which can be exactly obtained by solving linear equations and then used for characterizing synchronous states. Afterwards, we use inner coupling matrices and node dynamics to successively decompose the original network into a new network, composed of the external part and the internal part. Moreover, this new network can be proved to synchronize to the above invariant set by constructing the corresponding desired Lyapunov-like functions for the internal part and the external part respectively. In particular, this result still holds if the coupling strength is disturbed slightly. Finally, examples with numerical simulations are given to illustrate the validity and applicability of our theoretical results.