Graduate Student University of Kentucky Lexington, Kentucky, United States
Abstract:
Background: Reactivation of latent EHV-1 can result in horizontal spread, leading to abortion and/or myeloencephalopathy (EHM). Historically, the trigeminal ganglion (TG) and upper respiratory tract associated lymphatics (RALT) have been identified as latency sites. An experimental EHV-1 infection study suggested additional sites of EHV-1 persistence after recent intranasal infection.
Hypothesis/
Objectives: Alternative sites of EHV-1 persistence exist and can be detected in a random horse population.
Animals: Animals included 26 horses or ponies over 1 year of age with a postmortem interval less than 24 hours, submitted to the University of Kentucky Veterinary Diagnostic Laboratory (UKVDL) for necropsy.
Methods: The trigeminal ganglion (TG); dorsal root ganglion (DRG); sympathetic trunk (ST); pharyngeal roof (PhR); retropharyngeal (retLn) and mesenteric (mesLn) lymph nodes. Tissues were formalin fixed and paraffin embedded. Block sections underwent DNA extraction (QIAamp FFPE tissue kit, QIAGEN, Germany). Semi-quantitative polymerase chain reaction (sqPCR) was used to estimate EHV-1 genomic DNA.
Results: 17 male and 9 female (predominately Thoroughbred) horses with age range 1 – 25 years (8.90 ± 6.89; median = 7; mode 2) were included. Results are reported in table 1.
Conclusion and Clinical Importance: This study confirms the TG and RALT as tissues of EHV-1 persistence. However, EHV-1 genome copies were more frequent in PhR than in retLn. This is the first reported detection of EHV-1 genome in the ST of a random horse population. High abundance of EHV-1 genome in 2 PhR suggests lytic infection. A larger sample size is required for independent confirmation.
