The accumulation of protein aggregates is toxic and linked to different diseases such as neurodegenerative disorders, but the role of the immune system to target and destroy aggregate-carrying cells is still relatively unknown. Here we show a substrate-specific presentation of antigenic peptides to the direct MHC class I pathway via autophagy. We observed no difference in presentation of peptides derived from the viral EBNA1 protein following suppression of autophagy by knocking down Atg5 and Atg12. However, the same knock down treatment suppressed the presentation from ovalbumin. Fusing the aggregate-prone poly-glutamine (PolyQ) to the ovalbumin had no effect on antigen presentation via autophagy. Interestingly, fusing the EBNA1-derived gly-ala repeat (GAr) sequence to ovalbumin rendered the presentation Atg5/12 independent. We also demonstrate that the relative levels of protein expression did not affect autophagy-mediated antigen presentation. These data suggest a substrate-dependent presentation of antigenic peptides for the MHC class I pathway via autophagy and indicate that the GAr of the EBNA1 illustrates a novel virus-mediated mechanism for immune evasion of autophagy-dependent antigen presentation.

Department of Medical Biosciences Building 6M Umeå University 901 85 Umeå Sweden

ICCVS University of Gdańsk Science ul Wita Stwosza 63 80 308 Gdańsk Poland

Inserm UMRS1131 Institut de Génétique Moléculaire Université Paris 7 Hôpital St Louis F 75010 Paris France

Institut Necker Enfants Malades INSERM U1151 CNRS UMR 8253 Université de Paris Faculté de Médecine Necker France

ISP INRAE Université de Tours UMR1282 Tours Nouzilly France

RECAMO Masaryk Memorial Cancer Institute Zluty kopec 7 65653 Brno Czech Republic

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