Treatment of limb wounds of horses with orf virus IL-10 and VEGF-E accelerates resolution of exuberant granulation tissue, but does not prevent its development.
Authors: Wise Lyn M, Bodaan Christa J, Stuart Gabriella S, Real Nicola C, Lateef Zabeen, Mercer Andrew A, Riley Christopher B, Theoret Christine L
Journal: PloS one
Summary
# Editorial Summary: Orf Virus Proteins and Equine Limb Wound Healing Exuberant granulation tissue remains a significant clinical challenge in equine limb wound management, characterised by excessive inflammatory infiltration and dysfunctional angiogenesis that substantially delays healing—a problem that does not occur in body wounds or those left unbandaged. Wise and colleagues applied orf virus-derived interleukin-10 and vascular endothelial growth factor-E topically to experimentally induced bandaged limb wounds in four horses (alongside matched body wounds as controls), administering treatments at day 1 and day 8 whilst monitoring healing progression, histological changes, inflammatory markers, and gene expression through to complete epithelialisation. Although viral protein treatment failed to prevent exuberant granulation tissue development or accelerate overall healing time, it significantly enhanced epithelialisation and angiogenesis, notably reducing vascular occlusion and necrosis within granulation tissue and decreasing epidermal rete ridge formation without suppressing inflammatory cell infiltration. The findings suggest these viral proteins act as pro-reparative agents rather than anti-inflammatory modulators, offering a targeted mechanism to improve tissue quality and promote resolution of established exuberant granulation tissue rather than preventing its formation. For practitioners managing chronic limb wounds, this indicates potential benefit in shifting treatment focus from inflammation suppression alone towards promoting functional vascular and epidermal repair to facilitate exuberant granulation tissue remodelling.
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Practical Takeaways
- •Orf virus proteins show promise for improving vascular and epidermal repair in limb wound healing, but cannot prevent EGT formation when bandaging is required—consider as adjunct to other EGT management strategies rather than standalone prevention
- •The improvement in blood vessel quality and epithelialisation without reducing inflammation suggests these viral proteins work through mechanisms independent of inflammation suppression; this may be relevant for combination therapy approaches
- •Current evidence is limited to 4 horses; larger studies needed before clinical application can be recommended for routine practice
Key Findings
- •Orf virus IL-10 and VEGF-E did not prevent EGT formation or accelerate overall wound healing in bandaged limb wounds
- •Viral protein treatment increased epithelialisation and angiogenesis in limb wounds despite persistent inflammation
- •Healed wounds treated with viral proteins showed less vascular occlusion, reduced vessel death, and fewer epidermal rete ridges compared to controls
- •Body wounds did not develop EGT regardless of treatment, confirming location-specific factors in EGT pathogenesis