Use of tissue-specific microRNA to control pathology of wild-type adenovirus without attenuation of its ability to kill cancer cells

PLoS Pathog. 2009 May;5(5):e1000440. doi: 10.1371/journal.ppat.1000440. Epub 2009 May 22.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / genetics
  • Adenoviridae / physiology*
  • Adenovirus E1A Proteins / genetics
  • Adenovirus E1A Proteins / metabolism
  • Alanine Transaminase / blood
  • Amino Acid Sequence
  • Animals
  • Artificial Gene Fusion
  • Aspartate Aminotransferases / blood
  • Binding Sites / genetics
  • Cell Line, Tumor
  • Fluorescence
  • Gene Expression Regulation, Viral
  • Hepatocytes / metabolism
  • Hepatocytes / pathology
  • Hepatocytes / virology*
  • Humans
  • Liver / metabolism
  • Liver / pathology
  • Liver / virology
  • Liver Neoplasms, Experimental / metabolism
  • Liver Neoplasms, Experimental / virology
  • Mice
  • Mice, Inbred BALB C
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • Molecular Sequence Data
  • Oncolytic Virotherapy
  • Tissue Distribution
  • Whole Body Imaging


  • Adenovirus E1A Proteins
  • MicroRNAs
  • Aspartate Aminotransferases
  • Alanine Transaminase