Induction of Epstein-Barr Virus Lytic Replication
Beth Israel Deaconess Medical Center, Boston, Dr. Joyce Fingeroth
Student Presenter: Anastasia Hyrina Project Advisor: Craig Woodard
Epstein-Barr virus (EBV) is a member of the herpesvirus family and is one of the
most common human viruses. In the United States, 95% of adults between 35 and 40 years of age have been infected with EBV1. EBV is the etiological agent of infectious mononucleosis and is associated with a number of diverse lymphomas and epithelial cancers, including African Burkitt's lymphoma, nasopharyngeal carcinoma and gastric malignancies2.
Though EBV primarily infects B lymphocytes and epithelial cells, the sequence of
infection is not well understood. In infected B cells, EBV establishes persistent latent infections. The latent state of the virus in a cell is characterized by expression of a small subset of viral genes and the latent membrane proteins, which are essential for induction and maintenance of cellular proliferation and viral latency. Despite the fact that latency is a predominant state of the life cycle in the B cells and in virus-associated malignancies, the virus must replicate lytically in order to be passed from cell to cell and among individuals. Lytic reactivation of EBV from its latent state leads to expression of the majority of viral genes and release of the viral progeny that are capable of infecting new cells2.
The latent-to-lytic cycle switch has been extensively investigated because of its
obvious implications for EBV associated malignant diseases and a future therapy for EBV positive cancers. To my knowledge, previous studies on EBV induction have been investigated only in B cells and epithelial cells, which are types of cell lines that are naturally infected by the virus. In the present study, I proposed a novel method for EBV lytic induction in the virus infected erythroleukemic cell line, K562. K562 is a highly undifferentiated multipotent leukemia cell line that can be induced to differentiate to erythroid, myeloid or megakaryocytic lineages3. A previous study demonstrated that hydroxyurea, a ribonucleoside diphosphate reductase inhibitor, induces K562 cell differentiation through activation of p38 kinase, one of a group of MAP kinases4. Here, I hypothesized that induced differentiation of K562 EBV cells with hydroxyurea will stimulate the switch from latent-to-lytic cycle and lead to more efficient viral replication and production. The study has thus far shown there was no complete viral production induced by differentiation of K562 EBV infected cell lines but has not ruled out the initiation of abortive viral replication.
1Epstein-Barr Virus and Infectious Mononucleosis. Available from: www.cdc.gov/ncidod/diseases/ebv.htm 2 Rickinson, A.B., Kieff, E. Epstein-barr virus. In: Fields, B.N., Knipe, D.M., Howley, P.M., editor. Fields Virology. 5th ed. Philadelphia: Lippincott-Williams & Wilkins; 2007. p. 2655-2700 3 Yu G, Smithgall TE, Glazer RI. K562 leukemia cells transfected with the human c-fes gene acquire the ability to undergo myeloid differentiation. J Biol Chem. 1989 Jun 15;264(17):10276-81. 4 Park JI, Choi HS, Jeong JS, Han JY, Kim IH. Involvement of p38 kinase in hydroxyurea-induced differentiation of K562 cells. Cell Growth Differ. 2001 Sep;12(9):481-6.
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