Prevalence of equine gammaherpesviruses on breeding farms in Turkey and development of a TaqMan MGB real-time PCR to detect equine herpesvirus 5 (EHV-5).

The research article reveals the high prevalence of Equine herpesvirus type 2 (EHV-2) and EHV-5 in Arabian horse populations in Turkey. A new diagnostic technique involving real-time PCR was also developed, proving more accurate and efficient in detecting EHV-5.

Research Objective

• The primary goal of the study was to investigate the prevalence of EHV-2 and EHV-5 in Arabian horse populations from breeding farms in Turkey. This investigation utilized nested PCR to understand the epidemiology of the viruses, which are associated with respiratory tract infections and low performance in racehorses.
• Another central goal was the development of a real-time quantitative PCR (qPCR) technique with a TaqMan® minor-groove-binder (MGB) probe to offer speedy and reliable detection of EHV-5.

Methodology

• Blood, and ocular and nasal swab samples were taken from the horses for screening by nested PCR. The research was conducted in three different cities (Eskişehir, Malatya, and Bursa).
• To create the EHV-5 qPCR, a set of primers and an MGB probe were designed. This equipment relies on the highly-conserved genomic region that encodes glycoprotein B (gB).

Key Findings

• The prevalence of EHV-2 and EHV-5 was found to be 59% and 62%, respectively, while the coinfection rate was around 45%. Thirty-seven isolates were identified as EHV-2 using nested PCR.
• The qPCR assay developed was effective in detecting EHV-5 down to a level of 10 molecules per reaction. It was specific to EHV-5 and didn’t respond to other types of herpesviruses found in horses (EHV-1, EHV-2, or EHV-4).
• When applied to field samples, the qPCR assay demonstrated a superior sensitivity compared to the established nested PCR technique, making it a promising tool for the swift and accurate detection of EHV-5.

Conclusions

• The research highlights the high prevalence of EHV-2 and EHV-5 in Arabian horse populations across Turkey, indicating the critical need for effective detection methods to manage and prevent viral outbreaks.
• The newly developed qPCR assay in this study represents a substantial improvement over existing techniques, presenting a faster, more reliable, and more sensitive method for the detection of EHV-5. Therefore, it is an excellent addition to other diagnostic methods for equine respiratory disease.