Interaction Of P10/p27 And Macrophage Migration Inhibitory Factor Promotes Avian Leukosis Virus Subgroup J Replication

Avian leukosis virus subgroup J（ALV-J）is an avian oncogenic retrovirus that induces myelocytoma and various other tumors in broilers and laying hens.It is widely popular in China,causing huge economic losses to my country’s poultry farming industry.Macrophage migration inhibitory factor（MIF）is a cytokine with various biological activities.It can not only inhibit the migration of macrophages and directly or indirectly participate in immune responses and enhance cell proliferation and viability,but also involved in the pathogenesis of the variety of pathogenic microbial infections.In recent years,more and more studies have demonstrated that ALV-J can hijack host factors to enhance its infection ability during its infection process.However,the specific role of MIF in this process is still unclear.This study found that ALV-J can activate the expression of MIF in host cells at the early stage of infection,and MIF is involved in the pathogenesis of various pathogenic microorganisms,which indicates that MIF may be involved in the process of ALV-J infection of host cells.In order to clarify the relationship between MIF expression and ALV-J infection,this study constructed a eukaryotic expression plasmid for MIF and an interference plasmid targeting MIF.Through overexpression and interference with MIF,it was found that the m RNA and protein levels of ALV-J were significantly rise and fall accordingly,demonstrating that MIF can promote the replication of ALV-J.The adsorption and internalization experiments of the virus demonstrated that MIF played a role in the internalization rather than adsorption stage of ALV-J infection.Furthermore,it was proved by ISO-1,a specific antagonist of MIF,that MIF participates in ALV-J infection process in the cytoplasm,and MIF participates in ALV-J replication through its activity as an enzyme.Subsequently,in order to determine whether MIF promotes its infection by interacting with ALV-J structural proteins,eukaryotic expression plasmids encoding ALV-J structural proteins Gag,Pol,and Env were constructed.Interacting ALV-J structural proteins,it was found that MIF interacted with ALV-J Gag protein in the cytoplasm.In order to further clarify the Gag subunit proteins that interact with MIF,the eukaryotic expression plasmid encoding six subunit proteins of Gag protein were constructed,including the encoding matrix protein p19（MA）,capsid protein p27（CA）,nucleocapsid protein p12（NC）,enzymatic protein p15,and two small peptides p2 and p10 with unknown functions were detected by laser confocal and co-immunoprecipitation techniques to detect the Gag subunit protein interacting with MIF.p10/p27 were detected and this process takes place in the cytoplasm.These results suggest that the subunit proteins p10 and p27 in the ALV-J Gag protein can recruit MIF,thereby promoting ALV-J infection.This study revealed for the first time the roles of subunit proteins p10/p27 of ALV-J Gag and host factor MIF in ALV-J infection,revealing a novel mechanism by which ALV-J recruits host factors to promote its infection through its own structural proteins.It provides a new theoretical support for in-depth understanding of the pathogenic mechanism of ALV-J and retrovirus.