The detection and phylogenetic analysis of equine herpesviruses 1, 4 and 5 identified in nasal swab samples of asymptomatic horses from Serbia and Bosnia and Herzegovina.

The study focuses on detecting and analyzing the genetic information of equine herpesviruses 1, 4, and 5 present in seemingly healthy, unvaccinated horses from Serbia and Bosnia and Herzegovina. It found that these viruses tended to be chronic and persistent, with some evidence pointing to a link between presence of the viruses and the horses’ living conditions.

Study Methodology

• The research involved the examination of nasal swabs from 112 seemingly healthy and unvaccinated horses of various ages, breeds and rearing conditions in Serbia and Bosnia and Herzegovina.
• The presence of equine herpesviruses 1, 4 and 5 was analyzed using multiplex nested PCR (Mn‑PCR) and virus isolation techniques.
• The detected viruses were then characterized using a method known as gB gene nucleotide sequencing.
• A phylogenetic analysis – a technique used to infer the evolutionary history and relationships of the identified viruses – was subsequently performed.

Results and Findings

• The research found that the infections with equine herpesviruses 1, 4, and 5 in the examined horses are chronic, subclinical (meaning they do not cause noticeable signs or symptoms), and persistent.
• It was confirmed that the identified viruses EHV-1 and EHV-5 were being actively shed by the horses, as evidenced by successful virus isolation.
• Significantly, the study established an association of the finding of equine herpesviruses with the rearing conditions of horses. Horses kept together in stables were found positive for at least one of the equine herpesviruses as compared to those that grazed freely or were reared individually.
• The research also found a varying frequency of EHV-5 across different age groups of horses. The virus was found most often in young horses, however, its incidence decreased in horses up to 10 years of age.

Phylogenetic Analysis and Strain Identification

• The phylogenetic analysis revealed similarities between the identified equine herpesviruses strains from the study and those found in Turkey and Germany.
• A notable level of genetic diverseness was observed particularly in relation to the discovered EHV-5 strains, when compared to EHV-1 and EHV-4.