Authors: Tallmadge Rebecca L, Žygelytė Emilija, Van de Walle Gerlinde R, Kristie Thomas M, Felippe M Julia B
Journal: Frontiers in veterinary science
Summary
# Editorial Summary Equine herpesvirus type 1 remains a significant challenge in equine practice due to its high transmissibility, variable clinical severity, and the inadequate protection afforded by current vaccines and antivirals. Researchers investigated whether manipulating the epigenetic state of the viral genome—specifically by inhibiting histone demethylase enzymes whilst simultaneously blocking viral replication—could suppress EHV-1 infection in cultured equine cells. In equine fetal kidney cells, combining ganciclovir (a nucleoside analogue) with OG-L002 (a histone demethylase inhibitor) proved most effective, reducing viral load to a mean of 7.1 DNA copies per cell compared with 42.0 in untreated controls at 24 hours post-infection, whilst also dampening early viral gene expression. However, neither drug alone nor in combination suppressed infection in peripheral blood leukocytes, suggesting that cell-type differences, drug penetrance, or metabolic factors limit efficacy in immune cells. Whilst these findings support the theoretical basis for epigenetic modulation of herpesvirus latency, translation to clinical application would require overcoming significant barriers around systemic drug delivery and effectiveness in the target tissues where EHV-1 establishes latency in vivo.
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Practical Takeaways
- •Epigenetic modulation via histone demethylase inhibitors combined with antivirals shows promise for reducing EHV-1 viral replication in vitro, but cell-type differences may limit effectiveness in vivo
- •This in vitro work provides rationale for further investigation of combined drug approaches, though efficacy in living horses requires evaluation of drug penetrance and bioavailability
- •Current findings are preliminary laboratory research and do not yet translate to clinical treatment recommendations for EHV-1 cases in practice
Key Findings
- •Combined treatment with ganciclovir and OG-L002 reduced EHV-1 viral load to 7.1 DNA copies per cell compared to 42.0 in control (83% reduction, p=0.0001) in equine fetal kidney cells at 24 hours post-infection
- •Ganciclovir alone reduced viral load to 22.3 copies (p=0.0005) and OG-L002 alone to 25.6 copies (p=0.005) in fetal kidney cells
- •Combined ganciclovir and OG-L002 treatment significantly decreased EHV-1 gene expression at 3 hours post-infection (p=0.0003) in fetal kidney cells
- •Neither ganciclovir nor OG-L002 suppressed EHV-1 infection in isolated peripheral blood leukocytes, suggesting cell-type-dependent drug efficacy