SELF-AMPLIFYING RNA VACCINATION AS A TOOL FOR TRYPANOSOMA CRUZI-SPECIFIC CD8 T CELL TARGET DISCOVERY

Simposio; Keystone Symposia: Transforming vaccinology; 2020

The parasite Trypanosoma cruzi is the causative agent of Chagas disease, a potentially life-threateninginfection that represents a major health problem in Latin America where one sixth of its population is atrisk of contracting the infection. Currently there are no effective vaccines to prevent the infection andtreatment is limited to the acute phase. In this work, we first performed a reverse vaccinology approachto identify and select novel potentially secreted antigens from amastigotes, the intracellular replicativestage of the parasite, that might be targeted by the CD8 T cell response of the host. Besides, weassessed the ability of self-amplifying RNA (saRNA) platforms based on alphavirus replicons as vaccinesto prime antigen specific CD8+ T cells that can be employed to test selected antigens.Thus, reporter genes (nanoluciferase and tdTomato) were cloned and RNA replicons were generated byin-vitro transcription reaction. We found that replicons based on either Semliki Forest Virus (SFV3) orVenezuelan equine encephalitis virus (VEEV) were able to express reporter genes upon in-vitrotransfection of MC57G cell line. Moreover, antigen expression in the cytosol allowed us to developantigen presentation assays in order to recall memory T cells in vitro. Preliminary vaccination studies inC57BL/6 mice with saRNA codifying for OVA or a T. cruzi antigen formulated with cationic liposomesshowed antigen specific CD8 T cell priming for SIINFEKL or VNHRFTLV peptide. Future experiments willbe focused on analyzing the ability of novel selected T. cruzi antigens to prime CTL responses in-vivo.