A New Exploration On Murine Gammaherpesvirus 68(MHV68)

Murine Herpesvirus 68(MHV68) belongs to gamma-herpesvirus family. Gamma-herpesvirus is closely related to some malignant tumors. For example, EBV(Epstein-Barr virus) is related to nasopharyngeal carcinoma and Burkitt’s lymphoma. KSHV(Kaposi’s sarcoma-associated herpesvirus) is the direct agent of Kaposi’s sarcoma(KS) and its genome can also be detected in nearly all Kaposi’s sarcoma. EBV and KSHV rarely infect species other than primates, and there is no suitable cell line for infection and replication of these two viruses. So, finding an alternative viral model to study EBV and KSHV seems to be extremely necessary. Luckily, MHV68 properly follows up with the research model: Approximately 78% of the open reading frame of MHV68 is homologous with EBV and KSHV. It can infect experimental mice and many kinds of cells in vitro, including epithelial cells and fibroblast cells of various mammals.In recent years, zebrafish, as an important model organism,has been widely used in the study of the mechanism of embryonic development and the research of human diseases. Compared to the mice, the zebrafish has many unique advantages in scientific research, such as low cost, harmless to the human body and the environment, easy to obtain the embryos and easy to raise and breed in the laboratory and so on. However, there is no report on the use of zebrafish to study MHV68.In this study, we infected zebrafish embryos,ZF4 cells,MEF cells lack of IKKα(MEF/IKKα-/-) and BHK(Baby Hamster Syrian Kidney)cells with MHV68.The specific research contents and results are as follows:1.When the zebrafish embryos have been infected with MHV68, the embryonic developmental delay happened. When the infected embryos have matured, fragment of MHV68 genes were detected in genomic DNA of the embryos. The expression of genes related to embryonic development and immune-associated genes were examined by Q-PCR in each stage of embryonic development. Only the expression level of TGFβ1(Transforming growth factorβ1)in MHV68-treated group was lower than that in control group.There was no obvious difference in both group about other genes:FGF3、IFNθ1、IFNθ3、ISG15、TNFα and the DNA virus sensor:DDX41、DHX9、cGAS、MAVS.2.When MEF/IKKα-/-cell has been infected with MHV68,the size of virus plaque was compared with that in control group. We found that the plaque size in MEF/IKKα-/-cell was the smallest.Finally, a conclusion can be drew that IKKα has a certain promotion effect on MEF cells in MHV68 infection.3.BHK cells were infected with MHV68 after pre-treating with bcIFNa and used for plaque forming assay. The plaque assay data demonstrated that the number of virus plaque of 300 ul bcIFNa group is less than those of 100 ul bcIFNa group and control group.It is suggested that bcIFNa can help BHK cells to resist MHV68 infection.