Transduction of retinoic acid-inducible gene 1 by Ebola virus-like particles enhances antigen-presentation

Abstract

Abstract Ebola virus (EBOV), a filovirus family member, is a highly pathogenic virus that causes Ebola hemorrhagic fever resulting in documented mortality rates in humans as high as 50%. EBOV virus-like particles (VLPs) are morphologically and biochemically similar to parental virus, yet they lack a genome and cannot replicate. We hypothesize that addition of a constitutionally active retinoic acid-inducible gene 1 (RIG-I) would enhance the ability of the EBOV VLPs to induce antigen-presentation from infected antigen-presenting cells. Expression of EBOV VP40 in 293T cells induces the spontaneous production of VLPs into the media supernatant and if expressed with EBOV glycoprotein (GP), will produce VLPs studded with the attachment GP. Recombinant chimeric constitutively active (ca)RIG-I-VP40 matrix and a nonfunctional mutant L58A (mu)RIG-I-VP40 matrix genes were constructed to produce VLPs containing constitutively active and nonfunctional RIG-I, respectively. Supernatant from 293Ts transfected with caRIG-I-VP40, muRIG-I-VP40 or VP40 along with GP expression plasmids were tested for the presence of VLPs. Western blotting of purified VLPs confirmed the presence of RIG-I in caRIG-I-VP40 and muRIG-I-VP40 VLPs. Monocyte-like THP-1 reporter cells were treated with nothing, VP40+GP, caRIG-I-VP40+GP and muRIG-I-VP40+GP VLPs as well as LPS and tested for induction of interferon signaling. CaRIG-I containing, but not muRIG-I containing VLPs induced interferon signaling as well as greater MHC I upregulation. Furthermore, CaRIG-I containing, but not muRIG-I containing VLPs induced greater levels of IL-2 production from treated mixed-lymphocyte reactions. Future studies will test the vaccine efficacy of caRIG-I containing VLPs.