# Exploring the Antiviral Potential of Tungsten Oxide Nanoparticles Against Herpes Simplex Virus Type 1: A Promising Alternative to Acyclovir

## TL;DR

This study shows that tungsten oxide nanoparticles can strongly inhibit HSV-1, a virus that causes cold sores and serious diseases, offering a promising alternative to current treatments.

## Contribution

The study introduces tungsten oxide nanoparticles as a novel and highly effective antiviral agent against HSV-1.

## Key findings

- Tungsten oxide nanoparticles reduced HSV-1 viral load by 99.4% and 99.9% at specific concentrations.
- Post-treatment with the nanoparticles significantly suppressed viral replication with inhibition rates up to 96.5%.
- The nanoparticles showed low toxicity to Vero cells at effective concentrations.

## Abstract

Herpes simplex virus type 1 (HSV‐1) is responsible for the majority of cold sores, herpetic keratitis‐induced blindness, profound skin lesions, and encephalitis that can be fatal. Currently, acyclovir and its derivatives are the first‐line therapy for the treatment of HSV‐1 infection. But there are drawbacks to these treatments: limited efficacy against drug‐resistant strains of the virus. Hence, it is of critical importance to explore and develop new antiviral drugs for HSV‐1. In the present study, we explored whether tungsten oxide nanoparticles (WO3NPs) were potent inhibitors of HSV‐1 infection as a new class of agent. WO3NPs were characterized by X‐ray diffraction (XRD), field‐emission scanning electron microscopy (FE‐SEM), Fourier transform infrared (FTIR) spectroscopy, and zeta potential analysis. Cytotoxicity of Vero cells caused by WO3NPs was determined by methyl thiazolyl tetrazolium (MTT) assay. The quantitative real‐time polymerase chain reaction (qRT‐PCR) assay was utilized for further verification of the action of the WO3NPs on HSV‐1. The cytotoxicity test showed low toxicity (<20%) of the rod‐shaped WO3NPs when they were assayed on Vero cells at concentrations of up to 700 μg/mL. When HSV‐1 was treated with WO3NPs at 700 µg/mL [20% cytotoxicity concentration (CC20); the concentration causing 20% cytotoxicity, ~80% cell viability] and 1000 µg/mL [50% cytotoxicity concentration (CC50); the concentration causing 50% cytotoxicity, ~50% cell viability] for 3 h, the viral load was significantly reduced, achieving inhibition rates of 99.4% and 99.9%, respectively. Additionally, experiments conducted after HSV‐1 infection of Vero cells (post‐treatment assays) indicated that WO3NPs at concentrations of 250, 500, and 750 µg/mL significantly suppressed viral replication, with inhibition rates of 82%, 87.5%, and 96.5%, respectively. WO3NPs have potent inhibitory effects on HSV‐1. Therefore, they can be considered potential candidates for therapeutic development against infections caused by this virus.