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Updated: Aug 14, 2026

Handling of the Cotton Rat in Studies for the Pre-clinical Evaluation of Oncolytic Viruses
06:13

Handling of the Cotton Rat in Studies for the Pre-clinical Evaluation of Oncolytic Viruses

Published on: November 24, 2014

An oncolytic viral mutant that delivers the CYP2B1 transgene and augments cyclophosphamide chemotherapy

M Chase1, R Y Chung, E A Chiocca

  • 1Molecular Neuro-oncology Laboratory, Massachusetts General Hospital-CNY6, Harvard Medical School, Charlestown, MA 02129, USA.

Nature Biotechnology
|May 21, 1998
PubMed

Insights

Engineered herpes simplex virus type 1 (HSV-1) targets tumors expressing mammalian ribonucleotide reductase (mRR). This virus, combined with cyclophosphamide, demonstrated enhanced oncolytic effects against tumor cells and xenografts.

Area of Science:

  • Oncolytic virotherapy
  • Molecular virology
  • Cancer biology

Background:

  • Herpes simplex virus type 1 (HSV-1) is a potential oncolytic agent.
  • Tumor cells often exhibit upregulated mammalian ribonucleotide reductase (mRR).
  • The p16/pRB tumor suppressor pathway regulates mRR expression.

Purpose of the Study:

  • To engineer a recombinant HSV-1 to selectively target tumor cells expressing mRR.
  • To evaluate the oncolytic efficacy of the engineered virus in combination with prodrugs.

Main Methods:

  • Inactivated viral ribonucleotide reductase (Hsrr, ICP6) in HSV-1.
  • Inserted rat CYP2B1 transgene for prodrug bioactivation.
  • Tested viral replication in tumor cells with varying mRR expression.
  • Assessed oncolytic effects in vitro and in vivo (subcutaneous xenografts in athymic mice).

Main Results:

  • Recombinant HSV-1 selectively replicated in tumor cells expressing mRR.
  • The mutant virus demonstrated potentiation of oncolytic effects when combined with cyclophosphamide.
  • Enhanced efficacy observed in cultured tumor cells and in vivo tumor xenografts.

Conclusions:

  • Engineered HSV-1 with inactivated Hsrr and CYP2B1 transgene shows tumor-selective replication.
  • Combination therapy with cyclophosphamide enhances the oncolytic potential of the engineered virus.
  • This approach offers a promising strategy for targeted cancer therapy.

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