Characterizing the Pathogenesis and Immune Response of Equine Herpesvirus 8 Infection in Lung of Mice.
Authors: Hu Leyu, Wang Tongtong, Ren Huiying, Liu Wenqiang, Li Yubao, Wang Changfa, Li Liangliang
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Equine herpesvirus type 8 (EHV-8) represents a significant threat to equine populations worldwide, causing abortion and severe respiratory disease particularly in donkeys and horses, yet its underlying pathogenic mechanisms remain poorly characterised. Researchers used BALB/c mice as an infection model, inoculating them with the EHV-8 SDLC66 strain and monitoring clinical signs, viraemia, tissue viral loads, and cytokine responses at multiple timepoints through to day 6 post-infection. Infected mice developed predictable clinical manifestations including lethargy, dyspnoea and weight loss; importantly, the virus successfully replicated in multiple tissues (liver, spleen, brain and lung) from day 4 onwards, with quantifiable titres confirmed at day 6. The infection triggered a characteristic inflammatory response dominated by rapid elevation of proinflammatory cytokines (IL-6, IL-1β and TNF-α) in lung tissue by day 4, with interferon-gamma response emerging only by day 6, suggesting a delayed adaptive immune component. These findings establish the mouse model as a viable tool for studying EHV-8 pathogenesis and indicate that the virus's respiratory pathology stems from direct pulmonary replication combined with acute inflammatory cytokine production—information that could inform future therapeutic strategies targeting either viral replication or excessive inflammatory damage in naturally infected equines.
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Practical Takeaways
- •EHV-8 infection causes acute respiratory disease with systemic dissemination; clinical monitoring for respiratory signs in exposed animals is warranted
- •Early immune response is primarily innate (proinflammatory cytokines); awareness of this response pattern may help inform timing of supportive care interventions
- •This mouse model provides a research tool for understanding EHV-8 pathogenesis, though findings require validation in natural equine hosts before clinical application
Key Findings
- •EHV-8 SDLC66 strain successfully replicated in BALB/c mice lungs, liver, spleen, and brain by 4-6 days post-infection
- •Infected mice exhibited clinical signs of respiratory disease including lethargy, dyspnea, weight loss, and viremia
- •Proinflammatory cytokines (IL-6, IL-1β, TNF-α) were significantly elevated at 4 and 6 dpi in lung tissue compared to controls
- •IFN-γ response was delayed, appearing only at 6 dpi, indicating a developing adaptive immune response