Human transbodies that interfere with the functions of Ebola virus VP35 protein in genome replication and transcription and innate immune antagonism

Abstract

Small molecular inhibitors and passive immunization against Ebola virus disease (EVD) have been tested in animal models, including rodents and non-human primates, as well as in clinical trials. Nevertheless, there is currently no Food and Drug Administration (FDA)-approved therapy, and alternative strategies must be pursued. The aim of this study was to produce cell-penetrable human single-chain antibodies (transbodies) that are able to interfere with the activities of interferon inhibitory domain (IID) of the VP35 protein, a multifunctional virulence factor of Ebola virus (EBOV). We speculated that effective VP35-IID-specific transbodies could inspire further studies to identify an alternative to conventional antibody therapies. Phage display technology was used to generate Escherichia coli-derived human single-chain antibodies (HuscFvs) that bind to IID. HuscFvs were linked to nona-arginine (R9) to make them cell penetrable. Transbodies of transformed E. coli clones 13 and 3, which were predicted to interact with first basic patch residues (R9-HuscFv13), central basic patch, and end-cap residues (R9-HuscFv3), effectively inhibited EBOV minigenome activity. Transbodies of E. coli clones 3 and 8 antagonized VP35-mediated interferon suppression in VP35-transduced cells. We postulate that these transbodies formed an interface contact with the IID central basic patch, end-cap, and/or residues that are important for IID multimeric formation for dsRNA binding. These transbodies should be evaluated further in vitro using authentic EBOV and in vivo in animal models of EVD before their therapeutic/prophylactic effectiveness is clinically evaluated.

Acknowledgements

This study was supported by a grant from the Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand (R015834001), and an NSTDA Chair Professor Grant funded by the Crown Property Bureau of Thailand (P-1450624). N.S.R. was supported by a TRF-RSA scholarship (RSA5780025).

Authors’ contributions

W.C.C. conceived the project. W.C.C., W.S.S., N.S.R. and Y.S.K. designed the experiments. W.S.S., S.J.V., and N.S.L. performed the experiments. W.C.C. and WSS interpreted the data, prepared the figures, and wrote the manuscript.

Conflict of interest

The authors declare that they have no conflict of interest.

Electronic supplementary material

Supplementary Information accompanies this paper at (10.1038/s41426-018-0031-3).