# Antiviral effect of poly(styrene 4-sulfonate) (PSSNa) on feline calicivirus oral infections in cats—field study

## TL;DR

This study shows that PSSNa is safe and reduces viral load in cats with feline calicivirus, though more research is needed due to study limitations.

## Contribution

The study provides preliminary evidence of PSSNa's antiviral efficacy and safety in treating FCV in cats.

## Key findings

- PSSNa showed a significant decrease in viral load compared to placebo.
- PSSNa had a favorable safety profile with no adverse effects observed.
- PSSNa was effective against multiple genetically diverse FCV isolates.

## Abstract

Feline calicivirus (FCV) infection causes nasal discharge, oral mucosa inflammation, ulcerations, gingivitis, and conjunctivitis, often progressing to chronic gingivostomatitis, severe pneumonia, and fatal systemic infections. With no antivirals currently available, poly(sodium 4-styrene sulfonate) (PSSNa) was identified in 2019 as a safe inhibitor in vitro. In this preliminary single-center, randomized, double-blind, placebo-controlled field study, we further characterized the PSSNa’s safety profile and tested its efficacy in cats after topical oral application. Twenty-eight cats were enrolled in the study, and they were initially treated with standard dental therapy, followed by adjuvant local oral application of PSSNa or placebo. After 4 weeks, PSSNa demonstrated a favorable safety profile with no adverse effects. The treatment group showed a significant decrease in viral load (p = 0.001) compared to placebo (p = 0.012). Disease symptoms improved significantly, though the oral health index remained unchanged. Additionally, PSSNa showed activity against multiple genetically diverse isolates, indicating a potential, exploratory link between genetic background and treatment outcome. Summarizing, this study presents initial data on the efficacy and tolerability of PSSNa treatment for FCV infections in cats. Nevertheless, several significant limitations should be acknowledged, including inconsistent drug administration by owners, non-sterile housing, sample size, variable oral disease severity, and concurrent treatments.