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Cell specific internal translation efficiency of Epstein–Barr virus present in solid organ transplant patients
Author(s) -
Isaksson Åsa,
Berggren Malin,
EkelandSjöberg Kerstin,
Samuelsson Tore,
Ricksten Anne
Publication year - 2007
Publication title -
journal of medical virology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 121
eISSN - 1096-9071
pISSN - 0146-6615
DOI - 10.1002/jmv.20854
Subject(s) - internal ribosome entry site , biology , untranslated region , messenger rna , microbiology and biotechnology , translation (biology) , virology , gene , genetics
The U leader exon in the 5′ untranslated region of the Epstein–Barr virus nuclear antigen 1 (EBNA1) gene contains an internal ribosome entry site, the EBNA internal ribosome entry segment (IRES), which promotes cap‐independent translation and increases the expression level of the EBNA1 protein. It was previously reported that immunosuppressed organ transplanted patients showed an alternatively spliced EBNA1 transcript, excluding the EBNA IRES element. To further investigate the function of the EBNA IRES, sequence analysis of the EBNA IRES mRNA was performed in samples from seven organ transplant patients. Two nucleotide changes, G → A at position 67531 and C → U at position 67585 were found in the EBNA IRES mRNA, relative to the corresponding genomic Epstein–Barr virus (EBV) sequence in all patients. Moreover, the patient derived EBNA IRES mRNA was shown to differ from the IRES mRNA derived from the cell line B95.8 at position 67531 and from the cell lines Rael and P3HR1 at positions 67531 and 67585. cDNA from the various EBNA IRES sequences were cloned into bicistronic vectors, respectively, and used in transient transfection experiments in six human cell lines. The patient specific sequence significantly decreased the IRES activity in T‐cells, while the base changes had no significant impact on the activity in B‐ or in epithelial cells. The genetic mechanisms behind EBV‐associated diseases are complex, involving gene regulation by alternative promoters, alternative splicing, and translational control. The nucleotide changes in the patient specific EBNA IRES transcript and its influence on the translational activity, might illustrate new strategies utilised by the EBV to adapt to the immune control in patients with EBV associated diseases. J. Med. Virol. 79:573–581, 2007. © 2007 Wiley‐Liss, Inc.