Immunohistochemical Evaluation of <scp>TLR</scp> ‐4, <scp>HSP</scp> ‐70 and Caspase‐3 Expressions in Lesional Areas of Ecthyma Disease

BACKGROUND: Contagious ecthyma (Orf) is a highly contagious, economically significant disease affecting sheep, goats and wild small ruminants, caused by the resilient Orf virus (ORFV). It produces thick, crusted lesions around the mouth and nostrils, especially in animals aged 3-4 months, sometimes causing near 100% mortality in immunocompromised young animals. ORFV targets epithelial cells, evading host defences and impairing feeding, which leads to malnutrition and production losses. Key molecules such as Toll-like receptor (TLR)-4, heat shock protein (HSP)-70 and caspase-3 play crucial roles in innate immunity, stress responses and apoptosis. OBJECTIVES: This study investigates TLR-4, HSP-70 and caspase-3 expression in the lesions of naturally infected animals. MATERIALS AND METHODS: A total of 37 ecthyma lesions were examined histopathologically and immunohistochemically. CONCLUSIONS AND CLINICAL RELEVANCE: All three markers showed increased expression in both epithelial cells and inflammatory infiltrates within the lesions. These findings indicate that TLR-4, HSP-70 and caspase-3 may play pivotal roles in the immunopathogenesis of contagious ecthyma and could represent potential diagnostic or therapeutic targets. Further research is warranted to clarify their mechanistic involvement and potential applications in disease control strategies.