Equid herpesvirus type 1 activates platelets.
Authors: Stokol Tracy, Yeo Wee Ming, Burnett Deborah, DeAngelis Nicole, Huang Teng, Osterrieder Nikolaus, Catalfamo James
Journal: PloS one
Summary
# Editorial Summary: EHV-1-Induced Platelet Activation and Thrombosis Equid herpesvirus type 1 (EHV-1) causes significant morbidity through abortion and neurological disease, with vessel thrombosis in the placenta and spinal cord implicated as a primary pathological mechanism; however, the biological pathway triggering clot formation has remained unclear. Using in vitro platelet activation assays with two EHV-1 strains (RacL11 and Ab4), researchers demonstrated that viral exposure at modest concentrations activated equine platelets within 10 minutes, inducing alpha-granule secretion (evidenced by P-selectin expression) and microvesiculation—the shedding of small phosphatidylserine-positive membrane particles—with RacL11 producing more pronounced effects. The cascade appeared to operate through viral activation of the tissue factor pathway: blocking factors VII or X substantially reduced platelet activation markers, whilst adding purified factor VIIa to factor VII-deficient plasma restored the response, indicating that tissue factor triggers factor X activation and downstream thrombin generation. Notably, a glycoprotein C-deficient viral mutant activated platelets normally, suggesting the mechanism involves different viral surface determinants, and infectious virus recovery from platelets implied direct viral-platelet contact rather than purely soluble mediators. These findings provide mechanistic insight into EHV-1 pathogenesis and suggest that therapeutic targeting of platelet activation or the tissue factor pathway warrants investigation as an adjunctive approach to managing EHV-1 neurological cases and reproductive losses in affected herds.
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Practical Takeaways
- •EHV-1-induced platelet activation and thrombosis provides a mechanistic explanation for abortion and neurological complications in infected horses, though this in vitro finding requires validation in clinical cases
- •Understanding the tissue factor-dependent pathway of platelet activation may inform future therapeutic strategies targeting thrombotic complications in EHV-1 outbreaks
- •This is laboratory research; clinicians should continue following established EHV-1 management protocols while this mechanism is further studied
Key Findings
- •EHV-1 strains (RacL11 and Ab4) activate equine platelets within 10 minutes at ≥0.5 plaque forming units/cell, triggering α-granule secretion and microvesiculation
- •Virus-induced platelet activation occurs via tissue factor-dependent pathway leading to factor X activation and thrombin generation
- •RacL11 strain caused more pronounced microvesiculation than Ab4 strain
- •Infectious virus can be recovered from EHV-1-exposed platelets, indicating direct platelet-virus interaction