mRNA Structural Constraints on EBNA1 Synthesis Impact on In Vivo Antigen Presentation and Early Priming of CD8+ T Cells

PLoS Pathogens

Ross L. Tellam¹  Nathan P. Croft²  Purnima Bhat³  Warren Kaplan⁴  Michelle Martinez⁵  Judy T. Tellam⁵  Rajiv Khanna⁵  Jie Zhong⁵  Lea Lekieffre⁵ 

[1] CSIRO Agriculture Flagship, Commonwealth Scientific and Industrial Research Organization, Brisbane, Queensland, Australia;Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia;Medical School, Australian National University, Canberra, Australian Capital Territory, Australia;Peter Wills Bioinformatic Centre, Garvan Institute of Medical Research, Sydney, New South Wales, Australia;QIMR Centre for Immunotherapy and Vaccine Development and Tumour Immunology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia

关键词: T cells;    Cytotoxic T cells;    Messenger RNA;    Protein translation;    Antigen presentation;    Lymph nodes;    Cell staining;    Viral persistence;    latency;   

DOI  :  10.1371/journal.ppat.1004423

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Recent studies have shown that virally encoded mRNA sequences of genome maintenance proteins from herpesviruses contain clusters of unusual structural elements, G-quadruplexes, which modulate viral protein synthesis. Destabilization of these G-quadruplexes can override the inhibitory effect on self-synthesis of these proteins. Here we show that the purine-rich repetitive mRNA sequence of Epstein-Barr virus encoded nuclear antigen 1 (EBNA1) comprising G-quadruplex structures, limits both the presentation of MHC class I-restricted CD8+ T cell epitopes by CD11c+ dendritic cells in draining lymph nodes and early priming of antigen-specific CD8+ T-cells. Destabilization of the G-quadruplex structures through codon-modification significantly enhanced in vivo antigen presentation and activation of virus-specific T cells. Ex vivo imaging of draining lymph nodes by confocal microscopy revealed enhanced antigen-specific T-cell trafficking and APC-CD8+ T-cell interactions in mice primed with viral vectors encoding a codon-modified EBNA1 protein. More importantly, these antigen-specific T cells displayed enhanced expression of the T-box transcription factor and superior polyfunctionality consistent with the qualitative impact of translation efficiency. These results provide an important insight into how viruses exploit mRNA structure to down regulate synthesis of their viral maintenance proteins and delay priming of antigen-specific T cells, thereby establishing a successful latent infection in vivo. Furthermore, targeting EBNA1 mRNA rather than protein by small molecules or antisense oligonucleotides will enhance EBNA1 synthesis and the early priming of effector T cells, to establish a more rapid immune response and prevent persistent infection.

【 授权许可】

CC BY