Messenger RNA Sequence Rather than Protein Sequence Determines the Level of Self-synthesis and Antigen Presentation of the EBV-encoded Antigen, EBNA1
Keyword
Epstein-Barr-VirusSarcoma-Associated Herpesvirus
T-Cell Recognition
Open Reading Frame
Nuclear Antigen-1
Kaposis-Sarcoma
Simian Homologs
Immune Evasion
Endogenous Presentation
Viral Evasion
Date
2012-12-27
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Tellam JT, Lekieffre L, Zhong J, Lynn DJ, Khanna R (2012) Messenger RNA Sequence Rather than Protein Sequence Determines the Level of Self-synthesis and Antigen Presentation of the EBV-encoded Antigen, EBNA1. PLoS Pathog 8(12): e1003112. doi:10.1371/journal.ppat.1003112Abstract
Viruses establishing persistent latent infections have evolved various mechanisms to avoid immune surveillance. The Epstein-Barr virus-encoded nuclear antigen, EBNA1, expressed in all EBV-associated malignancies, modulates its own protein levels at quantities sufficient to maintain viral infection but low enough so as to minimize an immune response by the infected host cell. This evasion mechanism is regulated through an internal purine-rich mRNA repeat sequence encoding glycine and alanine residues. In this study we assess the impact of the repeat's nucleotide versus peptide sequence on inhibiting EBNA1 self-synthesis and antigen presentation. We demonstrate that altered peptide sequences resulting from frameshift mutations within the repeat do not alleviate the immune-evasive function of EBNA1, suggesting that the repetitive purine-rich mRNA sequence itself is responsible for inhibiting EBNA1 synthesis and subsequent poor immunogenicity. Our comparative analysis of the mRNA sequences of the corresponding repeat regions of different gammaherpesvirus maintenance homologues to EBNA1 highlights the high degree of identity between the nucleotide sequences despite very little homology in the encoded amino acid sequences. These studies demonstrate the importance of gammaherpesvirus purine-rich mRNA repeat sequences on antigenic epitope generation and evasion from T-cell mediated immune control, suggesting novel approaches to prevention and treatment of latent infection by this class of virus.Funder
National Health & Medical Research Council AustraliaGrant Number
496684 APP1005091; 496712ae974a485f413a2113503eed53cd6c53
http://dx.doi.org/10.1371/journal.ppat.1003112