Effect of Storage Conditions on Equine Herpesvirus-1 DNA Detection in Equine Urine

Equine herpesvirus-1 (EHV-1) is a major equine pathogen causing myeloencephalopathy, abortion, and respiratory disease. Following the detection of EHV-1 DNA in urine from naturally infected horses, urine has emerged as a potential complementary non-invasive specimen for molecular diagnosis. However, the influence of storage conditions on EHV-1 DNA stability remains unknown. Urine from six healthy horses was experimentally inoculated with EHV-1 (104 copies/µL) and stored at room temperature (25 °C) or under refrigeration (4 °C), with or without a commercial urine preservative, or at −80 °C without preservative. Viral DNA was quantified by qPCR over 30 days, and viral infectivity was explored by cell culture. Detectable EHV-1 DNA declined significantly during the first 24 h at room temperature and under refrigeration and remained relatively stable thereafter. Refrigeration partially improved the preservation of detectable viral DNA, whereas storage at −80 °C provided the greatest stability among the conditions evaluated over the 30-day study period. The commercial preservative provided no consistent benefit. These findings provide preliminary evidence to inform storage practices for equine urine samples intended for EHV-1 molecular diagnosis. Further studies involving naturally infected horses and additional freezing temperatures are needed to establish definitive recommendations for clinical sample handling.