Design of an Interferon-Resistant Oncolytic HSV-1 Incorporating Redundant Safety Modalities for Improved Tolerability

Area of Science:

• Oncolytic virotherapy
• Gene therapy
• Herpes simplex virus engineering

Background:

• Next-generation oncolytic viruses need to be potent, immunogenic, and safe.
• Herpes simplex virus 1 (HSV-1) is a common platform for oncolytic virus development.

Purpose of the Study:

• To engineer a novel HSV-1 vector with enhanced oncolytic potency, tumor specificity, and improved safety profile.
• To develop a virus resistant to host immune responses and with reduced neurovirulence.

Main Methods:

• Modified a joint-region deleted HSV-1, retaining ICP34.5 and mutating UL37 to inhibit axonal transport.
• Inserted cell-type-specific microRNA (miRNA) target cassettes into essential viral genes (ICP4, ICP27, UL8).
• Utilized a small interfering RNA (siRNA) screen to identify key viral replication genes for miRNA-mediated attenuation.

Main Results:

• The engineered HSV-1 vector demonstrated potent oncolytic activity in cancer cell lines, equivalent to the parental virus.
• The vector showed resistance to type I interferon compared to ICP34.5-deleted viruses.
• In vivo studies showed potent tumor growth inhibition and good tolerability, even at high intravenous doses.

Conclusions:

• The developed HSV-1 vector is a potent oncolytic agent with enhanced safety features, including reduced neurovirulence and interferon resistance.
• This modified virus represents a promising candidate for next-generation cancer virotherapy.