A yeast-based assay identifies drugs that interfere with immune evasion of the Epstein-Barr virus

• Main Authors: Cécile Voisset (Author), Chrysoula Daskalogianni (Author), Marie-Astrid Contesse (Author), Anne Mazars (Author), Hratch Arbach (Author), Marie Le Cann (Author), Flavie Soubigou (Author), Sébastien Apcher (Author), Robin Fåhraeus (Author), Marc Blondel (Author)
• Format: Book
• Published: The Company of Biologists, 2014-04-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 1754-8403; 1754-8411; 10.1242/dmm.014308
• Keywords: EBV-associated cancers; Cell-based drug screening; EBNA1 GAr domain; Yeast-based models; Immune evasion; Doxorubicin; Daunorubicin; 5-fluorouracil; Medicine; R; Pathology; RB1-214
• Source: Disease Models & Mechanisms, Vol 7, Iss 4, Pp 435-444 (2014)

Epstein-Barr virus (EBV) is tightly associated with certain human cancers, but there is as yet no specific treatment against EBV-related diseases. The EBV-encoded EBNA1 protein is essential to maintain viral episomes and for viral persistence. As such, EBNA1 is expressed in all EBV-infected cells, and is highly antigenic. All infected individuals, including individuals with cancer, have CD8+ T cells directed towards EBNA1 epitopes, yet the immune system fails to detect and destroy cells harboring the virus. EBV immune evasion depends on the capacity of the Gly-Ala repeat (GAr) domain of EBNA1 to inhibit the translation of its own mRNA in cis, thereby limiting the production of EBNA1-derived antigenic peptides presented by the major histocompatibility complex (MHC) class I pathway. Here we establish a yeast-based assay for monitoring GAr-dependent inhibition of translation. Using this assay we identify doxorubicin (DXR) as a compound that specifically interferes with the GAr effect on translation in yeast. DXR targets the topoisomerase-II-DNA complexes and thereby causes genomic damage. We show, however, that the genotoxic effect of DXR and various analogs thereof is uncoupled from the effect on GAr-mediated translation control. This is further supported by the observation that etoposide and teniposide, representing another class of topoisomerase-II-DNA targeting drugs, have no effect on GAr-mediated translation control. DXR and active analogs stimulate, in a GAr-dependent manner, EBNA1 expression in mammalian cells and overcome GAr-dependent restriction of MHC class I antigen presentation. These results validate our approach as an effective high-throughput screening assay to identify drugs that interfere with EBV immune evasion and, thus, constitute candidates for treating EBV-related diseases, in particular EBV-associated cancers.