The Preliminary Research On Mechanism Of Host Stress Granules Induced By Newcastle Disease Virus

Newcastle disease virus is a single strand of negative-stranded RNA structure virus, belong to the paramyxovirus family. Newcastle disease virus can cause severe avian respiratory system, nervous system and intestinal diseases, and is highly contagious and mortality, often resulting in significant economic losses, and thus, it becomes a serious threat to the livestock industry. Nevertheless, Newcastle disease virus has also been found to have a number of diseases to human therapeutic effects, most of which comes as Newcastle disease virus oncolytic properties. Newcastle disease virus as an oncolytic factor application has been used as adjuvant immunotherapy drugs achieved a certain effect in melanoma, colon cancer, kidney cancer treatment.Stress Granules(SGs) is a reversible dynamic structure which can quickly formed when the mammalian cell encountered ambient pressure, which contain stalled translation initiation complexes, thereby reducing the overall cell translation rate. Stress granules play a role as a temporary repository to store such complexes, when the pressure is released to stimulate these translation complexes can be quickly released and recovery of protein synthesis, thus restoring the cell homeostasis. The formation of SGs may promote cell survival under pressure, especially when the virus infects cells, the formation of stress granules can inhibit the replication of the virus particles, thereby preventing the other cells have been violated. However, as virus is all obligate parasitic, whose replication are relied entirely on the host system, there are many viruses have evolved mechanisms to resist stress corresponding granulosa cells regulate the level of translation. In addition to reducing stress granule cells play a role other than the translational level, has also been confirmed by innate immune cells associated with pattern recognition receptors and inhibition of tumor cell hyperactivation mTORC pathway exists in close contact.In this study, the two marker protein of stress granules were detected by indirect immunofluorescence, as well as ways in which the formation of protein phosphorylation levels of WB testing, designed to verify that the Newcastle disease virus can induce stress granules HeLa cells, and by detected at different time points to verify the relationship between stress granules and Newcastle disease virus. The results showed that NDV can induce stress granules in HeLa cells, and the stress granules are present in the cell being sustained in the process of viral infection, present only in the case of respiratory syncytial virus infection process has been reported. To further verify the impact of stress granules on Newcastle disease virus replication level, the study also inhibited the production of stress granules by RNA interference, thereby detecting the level of viral replication and viral protein expression at the mRNA level. The results show that afte knock-down the stress granules, the titer level of viral replication and viral protein expression level of viral protein mRNA was significantly decreased. Thus, the stress granules are conducive to the formation of Newcastle disease virus replication in HeLa cells.In addition, to further explore some of the composition of Newcastle disease virus-induced stress granules, in particular the relationship between some important pattern recognition receptors and adapter molecules associated with innate immunity. In this study, indirect immunofluorescence assay and fluorescence quantitative methods were used to detect the stress granules with RIG-I, MAVS and Astrin of localization as well as downstream interferon mRNA expression levels in order for the oncolytic properties of Newcastle disease virus the relationship between stress granules and give a reasonable explanation. The results of this study showed that stress not only wrapped virus NP protein, also wrapped RIG-I, MAVS, Astrin other innate immune-related proteins, and stress granules can also detect the colocalization with dsRNA. However, after knocking-down the stress granules, the expression level of IFN was significantly decreased.This experiment confirmed that NDV can induce stress granules in HeLa cells, and this is conducive to viral replication. Also some pattern recognition receptors and innate immune related molecules while being wrapped in the SGs, but its impact on the downstream production of interferon is not clear. SG is now known to be associated with mutual innate immunity on many levels, and play a crucial role in the survival and apoptosis of tumor cells, hence, in the study of stress granules may be found in some of the antiviral effect of the treatment site with a broad spectrum of values, and the recommendations made very favorable tumor therapy. Meanwhile, although Newcastle disease virus is a pathogenic of avian, but it’s able to effectively replicate in human tumor cells and it can be oncolytic, indicating its existence the mechanism of antagonism capacity in some tumor cells.