title: mRNA Structural constraints on EBNA1 synthesis impact on in vivo antigen presentation and early priming of CD8+ T cells.
abstract: 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.
authors.affiliation: QIMR Centre for Immunotherapy and Vaccine Development and Tumour Immunology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Judy T
authors.initials: JT
authors.lastname: Tellam
authors.affiliation: QIMR Centre for Immunotherapy and Vaccine Development and Tumour Immunology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhong
authors.affiliation: QIMR Centre for Immunotherapy and Vaccine Development and Tumour Immunology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Lea
authors.initials: L
authors.lastname: Lekieffre
authors.affiliation: Medical School, Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Purnima
authors.initials: P
authors.lastname: Bhat
authors.affiliation: QIMR Centre for Immunotherapy and Vaccine Development and Tumour Immunology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Martinez
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.
authors.forename: Nathan P
authors.initials: NP
authors.lastname: Croft
authors.affiliation: Peter Wills Bioinformatic Centre, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.
authors.forename: Warren
authors.initials: W
authors.lastname: Kaplan
authors.affiliation: CSIRO Agriculture Flagship, Commonwealth Scientific and Industrial Research Organization, Brisbane, Queensland, Australia.
authors.forename: Ross L
authors.initials: RL
authors.lastname: Tellam
authors.affiliation: QIMR Centre for Immunotherapy and Vaccine Development and Tumour Immunology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.
authors.forename: Rajiv
authors.initials: R
authors.lastname: Khanna
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D039521:CD11c Antigen / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics*; D005260:Female; D005805:Genes, MHC Class I / Q000276:immunology; D008810:Mice, Inbred C57BL; D014176:Protein Biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics*
chemical_list: D039521:CD11c Antigen; D018984:Epitopes, T-Lymphocyte; D019309:Epstein-Barr Virus Nuclear Antigens; D012333:RNA, Messenger; C417029:EBV-encoded nuclear antigen 1