Ebola Virus Delta-Peptide Acts as an Enterotoxic Viroporin In Vivo

Abstract

Ebola virus (EBOV), part of the filovirus family, has a genome that encodes for a partly conserved, 40-residue polypeptide, called the delta peptide, which is produced during Ebola virus disease pathogenesis. Sequence-structure-function analysis and in vitro data suggest that the delta peptide is a viroporin, a term used to describe a diverse family of virally encoded pore-forming peptides and proteins involved in the replication and pathogenesis of numerous viruses. Full-length and conserved C-terminal EBOV delta peptide fragments permeabilize synthetic lipid bilayers and multiple cell types in vitro. Activity requires that the two conserved cysteines are connected by a disulfide linkage. Here, we follow up those results by testing delta peptides using an established mouse model of diarrheal pathology focusing on the small intestine. We hypothesized that the cell permeabilization observed against numerous cell types in vitro would correspond to intestinal pathology, in vivo. We found that the delta peptide exerts potent enterotoxic activity against mouse intestine upon introduction to a closed intestinal ileal loop, resulting in a diarrheal syndrome in the mice. The peak activity of the peptide occurs 9-12 hours after introduction of peptide into the intestinal loop. Histological examination of the intestinal architecture showed severe damage and loss of goblet cells. Our in vivo results demonstrate that the EBOV delta peptide is a potential novel therapeutic target, and neutralizing it could ameliorate some of the severe enterotoxic burden characteristic of EBOV disease pathogenesis. Accordingly, our focus is to generate a high-affinity neutralizing antibody to block the lytic activity of the delta peptide in vitro and in vivo as a potentially efficacious therapeutic agent against EBOV disease.