The Role Of Avian Influenza Virus NS1 Protein Antagonistic Interferon Level Difference In The Process Of NDV-AIV Co-infection

Avian influenza virus(AIV)and Newcastle disease virus(NDV)are both of the most important viruses worldwide that damage poultry and have similar clinical symptoms causing subclinical infection and respiratory syndrome in poultry.The co-infection of AIV and NDV is common worldwide,and there is mutual inhibition when AIV and NDV co-infection,Although study in NDV and AIV infection in vivo and in vitro exists interfere with each other,but most of these results based on epidemiological data and preliminary validation of the genetic level,this study NDV(Herts/33)and H5N1(A/mallard/Huadong/S/2005),H9N2(A/Hong Kong/1073/99)as the research object,established the NDV and AIV in vitro infection model with NDV and AIV are discussed in A separate copy differences when infection and infection.The role and possible mechanism of Aivns1 protein in NDV and AIV co-infection were investigated strain.NDV and AIV may have antagonism when co-infected.In this experiment,an in vitro co-infection model of NDV and AIV was established,and the effects of AIV and NDV on virus replication were tested at different periods of NDV and AIV infection.The results showed that NDV pre-infected cells can significantly reduce the expression of H9N2 subtype AIV NP protein,but NDV pre-infected cells has no effect on the expression of H5N1 subtype AIV NP protein.Secondly,pre-infected cells with H9N2 subtype AIV and H5N1 subtype AIV can significantly reduce the expression of NDV NP protein.Finally,the TBK1 pathway and IFN measurement showed that H9N2 subtype AIV could not inhibit NDV's phosphorylation of TBK1 and the up-regulation of IFN expression,while H5N1 subtype AI could inhibit NDV's phosphorylation of TBK1 and up-regulation of IFN.It shows that NDV can effectively inhibit the replication of H9N2 subtype AIV but cannot inhibit the replication of H5N1 subtype AIV;the difference of NDV inhibiting the replication of different subtypes of AIV may be related to IFN.Both H9N2 subtype AIV and H5N1 subtype AIV can effectively inhibit NDV replication.The function of the AIV NS1 protein is mainly to antagonize the host's IFN to ensure its normal replication.In order to explore whether the NS1 protein plays an important role in NDV's inhibition of AIV infection,this experiment successfully constructed a highly and weakly virulent NS1 replacement AIV infectious clone,and compared the effects of NDV infection on wild-type AIV and replacement of NS1 AIV replication and NDV-induced the antagonism of IFN.The results showed that NDV can significantly reduce the expression of H9N2 and H5N1-s H9NS1 NP proteins and inhibit their replication.At the same time,NDV pretreatment can inhibit H9N2 replication and cause IFN up-regulation.La Sota and H5N1,H5N1H9NS1 in vivo co-infection experiments show that NDV cannot inhibit the replication of H5N1 in vivo but can inhibit the replication of NS1 replacement strain H5N1_H9NS1,and when NDV first infects the body,H5N1_H9NS1causes more significant interference than H5N1Therefore,the NS1 protein antagonizes the function of IFN is a key factor that affects NDV's inhibition of AIV replication.In order to explore the effect of H9N2 on NDV-induced stress particles,the aggregation of G3BP1 when NDV was co-infected with H9N2_WTand H9N2_H5NS1was compared and verified by H9N2 NS1 protein overexpression vector and NDV infection.The results showed that both H9N2 and H9N2_H5NS1significantly inhibited the expression of G3BP1 during co-infection,and the inhibition of H9N2_H5NS1was deeper.It is suggested that different subtypes of AIV NS1 protein affects the degree of aggregation of G3BP1 during co-infection.The overexpression results show that H9N2 NS1 protein has a significant antagonistic effect on the formation of G3BP1 induced by NDV.In summary,during the co-infection of NDV and AIV,NS1_H5has a stronger ability to antagonize IFN than NS1_H9,and has a stronger inhibitory effect on G3BP1.This study reveals for the first time that the AIV NS1 protein is a key factor in the process of mutual inhibition of NDV-AIV co-infection.This study will lay the foundation for a better understanding of NDV-AIV co-infection and provide theoretical support for future disease prevention and control.