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Updated: Nov 4, 2025
Growth, Purification, and Titration of Oncolytic Herpes Simplex Virus
Published on: May 13, 2021
Growth, Purification, and Titration of Oncolytic Herpes Simplex Virus
Hong-My Nguyen1, Naresh Sah1, Melissa R M Humphrey2
1Department of Immunotherapeutics and Biotechnology, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center.
Abstract:
Oncolytic viruses (OVs), such as the oncolytic herpes simplex virus (oHSV), are a rapidly growing treatment strategy in the field of cancer immunotherapy. OVs, including oHSV, selectively replicate in and kill cancer cells (sparing healthy/normal cells) while inducing anti-tumor immunity. Because of these unique properties, oHSV-based treatment strategies are being increasingly used for the treatment of cancer, preclinically and clinically, including FDA-approved talimogene laherparevec (T-Vec). Growth, purification, and titration are three essential laboratory techniques for any OVs, including oHSVs, before they can be utilized for experimental studies. This paper describes a simple step-by-step method to amplify oHSV in Vero cells. As oHSVs multiply, they produce a cytopathic effect (CPE) in Vero cells. Once 90-100% of the infected cells show a CPE, they are gently harvested, treated with benzonase and magnesium chloride (MgCl2), filtered, and subjected to purification using the sucrose-gradient method. Following purification, the number of infectious oHSV (designated as plaque-forming units or PFUs) is determined by a "plaque assay" in Vero cells. The protocol described herein can be used to prepare high-titer oHSV stock for in vitro studies in cell culture and in vivo animal experiments.
Insights
This study details a method for amplifying oncolytic herpes simplex virus (oHSV) in Vero cells. The protocol enables the preparation of high-titer oHSV stocks for cancer immunotherapy research.
Area of Science:
- Oncolytic virotherapy
- Cancer immunotherapy
- Virology
Background:
- Oncolytic viruses (OVs) are a promising cancer treatment strategy.
- Oncolytic herpes simplex virus (oHSV) selectively targets and destroys cancer cells, stimulating anti-tumor immunity.
- Preclinical and clinical applications of oHSV are expanding, with talimogene laherparevec (T-Vec) being an FDA-approved example.
Purpose of the Study:
- To describe a straightforward laboratory protocol for amplifying oHSV.
- To outline essential techniques for preparing oHSV for experimental use.
- To provide a method for generating high-titer oHSV stocks.
Main Methods:
- Amplification of oHSV in Vero cells, monitoring for cytopathic effect (CPE).
- Harvesting infected cells, treatment with benzonase and MgCl2, followed by filtration.
- Purification using sucrose-gradient method and titration via plaque assay to determine plaque-forming units (PFUs).
Main Results:
- Successful amplification of oHSV in Vero cells.
- Demonstration of a complete protocol from viral growth to titration.
- Generation of high-titer oHSV stocks suitable for further studies.
Conclusions:
- The described protocol provides a reliable method for oHSV preparation.
- This method supports in vitro and in vivo research in cancer immunotherapy.
- Standardized oHSV stock preparation is crucial for experimental reproducibility.
