title: Use of tissue-specific microRNA to control pathology of wild-type adenovirus without attenuation of its ability to kill cancer cells.
abstract: Replicating viruses have broad applications in biomedicine, notably in cancer virotherapy and in the design of attenuated vaccines; however, uncontrolled virus replication in vulnerable tissues can give pathology and often restricts the use of potent strains. Increased knowledge of tissue-selective microRNA expression now affords the possibility of engineering replicating viruses that are attenuated at the RNA level in sites of potential pathology, but retain wild-type replication activity at sites not expressing the relevant microRNA. To assess the usefulness of this approach for the DNA virus adenovirus, we have engineered a hepatocyte-safe wild-type adenovirus 5 (Ad5), which normally mediates significant toxicity and is potentially lethal in mice. To do this, we have included binding sites for hepatocyte-selective microRNA mir-122 within the 3' UTR of the E1A transcription cassette. Imaging versions of these viruses, produced by fusing E1A with luciferase, showed that inclusion of mir-122 binding sites caused up to 80-fold decreased hepatic expression of E1A following intravenous delivery to mice. Animals administered a ten-times lethal dose of wild-type Ad5 (5x10(10) viral particles/mouse) showed substantial hepatic genome replication and extensive liver pathology, while inclusion of 4 microRNA binding sites decreased replication 50-fold and virtually abrogated liver toxicity. This modified wild-type virus retained full activity within cancer cells and provided a potent, liver-safe oncolytic virus. In addition to providing many potent new viruses for cancer virotherapy, microRNA control of virus replication should provide a new strategy for designing safe attenuated vaccines applied across a broad range of viral diseases.
authors.affiliation: Department of Clinical Pharmacology, University of Oxford, Oxford, United Kingdom.
authors.forename: Ryan
authors.initials: R
authors.lastname: Cawood
authors.forename: Hannah H
authors.initials: HH
authors.lastname: Chen
authors.forename: Fionnadh
authors.initials: F
authors.lastname: Carroll
authors.forename: Miriam
authors.initials: M
authors.lastname: Bazan-Peregrino
authors.forename: Nico
authors.initials: N
authors.lastname: van Rooijen
authors.forename: Leonard W
authors.initials: LW
authors.lastname: Seymour
mesh_terms: D000256:Adenoviridae / Q000235:genetics / Q000502:physiology*; D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000378:metabolism; D000410:Alanine Transaminase / Q000097:blood; D000595:Amino Acid Sequence; D000818:Animals; D019677:Artificial Gene Fusion; D001219:Aspartate Aminotransferases / Q000097:blood; D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D005453:Fluorescence; D015967:Gene Expression Regulation, Viral; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology / Q000821:virology*; D006801:Humans; D008099:Liver / Q000378:metabolism / Q000473:pathology / Q000821:virology; D008114:Liver Neoplasms, Experimental / Q000378:metabolism / Q000821:virology; D051379:Mice; D008807:Mice, Inbred BALB C; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D050130:Oncolytic Virotherapy; D014018:Tissue Distribution; D051598:Whole Body Imaging
chemical_list: D017500:Adenovirus E1A Proteins; D035683:MicroRNAs; D001219:Aspartate Aminotransferases; D000410:Alanine Transaminase