Prevalence of equine herpesvirus type 1 latency detected by polymerase chain reaction.

The researchers in this study have developed an improved method to detect the DNA of latent strains of equine herpesvirus type 1 (EHV-1) using polymerase chain reaction (PCR). They tested this method on 267 samples from 116 animals and discovered EHV-1 DNA in 88% of the samples.

Improved Polymerase Chain Reaction Method

• The study involved the development of an improved polymerase chain reaction (PCR) method. This method was used to detect the DNA of latent equine herpesvirus type 1 (EHV-1) strains from various sources.
• The improvement was realized through the use of three pairs of oligonucleotide primers spanning fragments of 333 bp, 226 bp, and 268 bp of the thymidine kinase (tk) gene, and one primer pair spanning 225 bp of the glycoprotein C (gC) gene.
• These primers were used in specific amplifications, while primers for EHV-4 PCR were also designed.
• To confirm the identity of tk PCR fragments from EHV-1, restriction digests with TaqI were used.

Sensitivity and Application of the Test

• The researchers found that the sensitivity to detect PCR products was further enhanced when visualized in silver-stained acrylamide gels.
• They applied the PCR assays to 267 samples, including pools of tissue, peripheral blood leukocytes (PBL) and nasal swabs of archived, farm, and abattoir specimens from a total of 116 animals.

Findings & Prevalence of EHV-1

• In the analyzed samples, the EHV-1 DNA was discovered in 88% of the cases. This indicates that the virus is widespread in the examined population.
• Interestingly, the study found that the prevalence of the EHV-1 latent or persistent form in adult horses was in line with previous reports. However, the prevalence was found to be higher than formerly described in foetuses and young foals.
• On the other hand, EHV-4 latency was not detected in the studied specimens from Brazil.