The Role Of Exosomes In MDV Infection

Chicken Marek's disease(MD)is a malignant lymphoproliferative neoplasm disease caused by Marek's disease virus(MDV),which seriously endangers the development of the poultry industry.There are 3 serotypes of MDV,of which type 1 is tumorigenic and mainly T cells.Domestic and foreign scholars have done a lot of research on the tumorigenic mechanism of MDV,but the specific mechanism is not very clear.Exosomes are a kind of extracellular small vesicles secreted by cells between 30nm and 150nm in diameter.They can carry proteins,microRNAs and other components,and play an important role in intercellular substance exchange and signal transmission.miRNA is a non-coding small RNA with a length of only 19-25 nt.Its own production and processing mechanism and function have obtained great research results.Particularly in human cancer diseases,miRNAs can be used not only as oncogenes but also as tumor suppressors in cancer diseases,and also as cancer markers.When it targets tumor suppressor,it can inhibit the targeted tumor suppressor gene and promote the development of cancer.In recent years,studies have also found that exosomes can affect tumor development and tumor cell migration through direct or indirect effects.PTEN is an important tumor suppressor gene discovered in recent years and is a negative regulator of the signaling pathway P13K/Akt/mTOR.Over the years,it has been found that PTEN affects the differentiation,proliferation,growth,migration and apoptosis of tumor cells.PTEN is very common in human disease research,but research on poultry cancer is extremely rare.Then MD is a model of poultry tumors.What role does exosomes and their components play in the development of MD during MDV infection?What are the miRNAs that target to PTEN,and how do they work?In this study,MDV was used as the research object to isolate and purify exosomes from chicken embryo fibroblasts(CEF)infected with Marek's virulent strain MD5 and uninfected CEF culture supernatants.Mass spectrometry(MS)and Western blot analysis showed that MDV-infected exosomes contain MDV viral proteins VP22,PP38,gB and other components.Cell proliferation tests have found that exosomes can stimulate chicken spleen cell proliferation of high-dose exosomes can induce lymphocyte IFN-y secretion;flow cytometry detection of MDV-infected exosomes inhibited CD4+,CD8+ T lymphocytes.The high-throughput sequencing of exosomes showed that 26 miRNAs were up-regulated and 257 miRNAs were down-regulated in MDV-infected compared with uninfected viral cell supernatants,of which 3 were predicted to target to PTEN,respectively miR-74.miR-72 and miR-43,further experiments found that miR-43 may target PTEN.After overexpression of miR-43,the mRNA level of PTEN was down-regulated,inhibiting apoptosis and promoting cell proliferation,which laid a foundation for determining the targeting relationship between miR-43 and PTEN,and also provided a new direction for the tumorigenic mechanism of MDV.