Deoxyribonucleic acid (DNA) damage response (DDR) is the fundamental cellular response for maintaining genomic integrity and suppressing tumorigenesis. The activation of ataxia telangiectasia-mutated (ATM) kinase is central to DNA double-strand break (DSB) for maintaining host-genome integrity in mammalian cells. Oncolytic Newcastle disease virus (NDV) can selectively replicate in tumor cells; however, its influence on the genome integrity of tumor cells is not well-elucidated. Here, we found that membrane fusion and NDV infection triggered DSBs in tumor cells. The late replication and membrane fusion of NDV mechanistically activated the ATM-mediated DSB pathway via the ATM-Chk2 axis, as evidenced by the hallmarks of DSBs, i.e., auto-phosphorylated ATM and phosphorylated H2AX and Chk2. Immunofluorescence data showed that multifaceted ATM-controlled phosphorylation markedly induced the formation of pan-nuclear punctum foci in response to NDV infection and F-HN co-expression. Specific drug-inhibitory experiments on ATM kinase activity further suggested that ATM-mediated DSBs facilitated NDV replication and membrane fusion. We confirmed that the Mre11-RAD50-NBS1 (MRN) complex sensed the DSB signal activation triggered by NDV infection and membrane fusion. The pharmacological inhibition of MRN activity also significantly inhibited intracellular and extracellular NDV replication and syncytia formation. Collectively, these data identified for the first time a direct link between the membrane fusion induced by virus infection and DDR pathways, thereby providing new insights into the efficient replication of oncolytic NDV in tumor cells. Various viruses have evolved a plethora of strategies to manipulate DNA damage machinery and commandeer cells to maximize their own replication. On the contrary, host cells have also evolved to maintain cellular genomic stability and suppress carcinogenesis through multifaceted cellular DNA damage response (DDR). Most studies have focused on the relationship between DNA virus replication and the host DDR pathway, but few have investigated the interface between the DDR pathway and ribonucleic acid (RNA) viruses, such as oncolytic Newcastle disease virus (NDV). In the present study, we report for the first time that F-HN co-expression and NDV infection trigger ataxia telangiectasia-mutated (ATM)-dependent DSB lesions in tumor cells to promote viral replication and syncytium formation, respectively. We found that late NDV infection and membrane fusion activated the ATM-Chk2 axis in tumor cells, which expands prior understanding of the membrane fusion process and NDV infection. Our findings reveal new links among oncolytic NDV replication, membrane fusion, and DDR and deepen insights into NDV replication.

The fusogenically activated F and HN proteins of virulent NDV induce complete autophagic flux in DF-1 and A549 cells. However, the effect of both glycoproteins on mitochondria remains elusive. Here, we found that F and HN cooperation increases mitochondrial biogenesis but does not cause the mitochondria damage. We observed that both glycoproteins change the morphological characteristics and spatial distribution of intracellular mitochondria. F and HN cooperate cooperatively to induce ER stress and UPRmt. Our preliminary data suggested that F and HN cooperatively disturb mitochondrial fusion–fission homeostasis to enhance mitochondrial biogenesis, and eventually meet the energy demand of syncytium formation.

Newcastle disease (ND), which is caused by Newcastle disease virus (NDV), can cause heavy economic losses to the poultry industry worldwide. It is characterised by extensive pathologies of the digestive, respiratory, and nervous systems and can cause severe damage to the reproductive system of egg-laying hens. However, it is unknown whether NDV replicates in the male reproductive system of chickens and induces any pathologies. In this study, we selected a representative strain (i.e. ZJ1) of the most common genotype (i.e. VII) of NDV to investigate whether NDV can induce histological, hormonal, and inflammatory responses in the testes of specific pathogen free (SPF) roosters. NDV infection increased the expression of toll like receptor TLR3, TLR7, MDA5, IFN-α, IFN-β, IFN-γ, IL-8, and CXCLi1 in the testes of NDV-infected roosters at 5 days post-infection (dpi). Severe histological changes, including decrease in the number of Sertoli cells and individualized, shrunken spermatogonia with pyknotic nuclei, were observed at 3 dpi. At 5 dpi, the spermatogenic columns were disorganized, and there were fewer cells, which were replaced by necrotic cells, lipid vacuoles, and proteinaceous homogenous material. A significant decrease in the plasma concentrations of testosterone and luteinizing hormone (LH) and the mRNA expression of their receptors in the testes, steroidogenic acute regulatory protein, cytochrome P450 side-chain cleavage enzyme, and 3β-hydroxysteroid dehydrogenase in the NDV-infected group was observed relative to those in the control group (P < 0.05). Collectively, these results indicate that NDV infection induces a severe inflammatory response and histological changes, which decrease the steroidogenesis.

Newcastle disease virus (NDV) which is pathogenic to chickens is characterized by dyspnea, diarrhea, nervous disorder and hemorrhages. However, the influence of different virulent NDV strain infection on the host gut microbiota composition is still poorly understood. In this study, twenty 21-day-old specific pathogen free (SFP) chickens were inoculated with either the velogenic Herts33 NDV strain, lentogenic La Sota NDV strain or sterile phosphate buffer solution (PBS). Subsequently, the fecal samples of each group were collected for 16S rRNA sequencing. The results showed that the gut microbiota were mainly dominated by Firmicutes, Bacteroidetes and Proteobacteria in both healthy and NDV infected chickens. NDV infection altered the structure and composition of gut microbiota. As compared to the PBS group, phylum Firmicutes were remarkably reduced, whereas Proteobacteria was significantly increased in the velogenic NDV infected group; the gut community structure had no significant differences between the lentogenic NDV infected group and the PBS group at phylum level. At genus level, Escherichia-Shigella was significantly increased in both the velogenic and lentogenic NDV infected groups, but the lactobacillus was only remarkably decreased in the velogenic NDV infected group. Collectively, different virulent strain NDV infection resulted in a different alteration of the gut microbiota in chickens, including a loss of probiotic bacteria and an expansion of some pathogenic bacteria. These results indicated that NDV strains with different virulence have different impacts on chicken gut microbiota and may provide new insights into the intestinal pathogenesis of NDV.

Viruses have evolved different strategies to hijack subcellular organelles during their life cycle to produce robust infectious progeny. Successful viral reproduction requires the precise assembly of progeny virions from viral genomes, structural proteins, and membrane components. Such spatial and temporal separation of assembly reactions depends on accurate coordination among intracellular compartmentalization in multiple organelles. Here, we overview the rearrangement and morphology remodeling of virus-triggered intracellular organelles. Focus is given to the quality control of intracellular organelles, the hijacking of the modified organelle membranes by viruses, morphology remodeling for viral replication, and degradation of intracellular organelles by virus-triggered selective autophagy. Understanding the functional reprogram and morphological remodeling in the virus-organelle interplay can provide new insights into the development of broad-spectrum antiviral strategies.