Detection of equine herpesvirus 3 in equine skin lesions by polymerase chain reaction.

This research explains the detection of equine herpesvirus 3 (EHV3) implicated in skin lesions on horse genitals by using a scientific method known as polymerase chain reaction (PCR). This study was instigated following an occurrence of visible blisters and ulcers on the genital area of 2 female horses and 1 male horse in a small herd.

Methods

• The first part of the research was to identify the possible cause of the skin lesions using the location and the clinical history. The primary diagnosis was equine coital exanthema, a disease caused by EHV3.
• For further investigation, scrapings were taken from the affected lesions on the two mares and submitted for testing. Several cell lines of equine origin were inoculated for viral isolation however, no cytopathic agents were detected.
• The skin scrapings were then processed for DNA extraction and and PCR amplification was carried out for herpesvirus DNA polymerase and DNA-packaging protein (terminase) genes using nested, degenerate primers targeted to regions of the herpesvirus genome known to be conserved.

Results

• The process yielded products of expected sizes confirming the presence of viral DNA. To further identify the virus, nucleotide sequencing of the products was undertaken. This revealed the presence of EHV3 in the extracted DNA.
• To further confirm this, an EHV3-specific PCR assay targeted to the gC gene was employed, which verified the detection of EHV3.

Contribution to Knowledge

• A new PCR assay targeted to the highly conserved DNA polymerase gene of EHV3 was developed using the novel EHV3 nucleotide sequence identified. This novel method promises to be specific and sensitive in detecting EHV3 in future research or diagnostic applications. This represents progress in the efforts to detect and manage EHV3 in horses.