Genetic Characterization of Equine Herpesvirus 1 from
Clinical Cases and Asymptomatic Horses in Serbia and Bosnia and
Herzegovina
Andrea Radalj1*, Nenad Milić1,
Oliver Stevanović2, Ljubiša Veljović3 and
Jakov Nišavić1
1Department
of Microbiology, University of Belgrade, Faculty of Veterinary
Medicine, Blvd. Oslobodjenja 18, 11000 Belgrade, Serbia; 2 Veterinary
Institute of the Republic of Srpska „Dr. Vaso Butozan“, Branka
Radičevića 18, 78000 Banja Luka, Republic of Srpska, Bosnia and
Herzegovina; 3Virology Department, Institute of
Veterinary Medicine of Serbia, Janisa Janulisa 14, 11000 Belgrade,
Serbia
*Corresponding author:
andrea.zoric@vet.bg.ac.rs
Abstract
Equine herpesvirus 1 (EHV-1) causes considerable
economic loss to the equine industry and is spread among susceptible animals
during the cycles of latency and reactivation, causing rhinopneumonitis,
abortion, and neurological disease. Nucleotide polymorphisms within ORF30 and
ORF68 sequences of the viral genome are associated with strain
neuropathogenicity and geographical origin. A total of 142 tissue and nasal swab
samples from apparently healthy unvaccinated horses were examined to ascertain
EHV-1 distribution, diversity, and clinical significance considering the results
of virus isolation, sequence analysis, and anamnestic data. The ORF30 and ORF68
molecular study of these circulating strains and archival isolates from abortion
storms aimed to contribute to the perception of strain pathogenicity and origin.
EHV-1 was detected by PCR and virus isolation in 81 and 45.1% of the analyzed
samples, respectively, and 82.1% of the representative samples were
neuropathogenic strains. The ORF68-based grouping was restricted by the
pronounced polymorphism of Balkan EHV-1 strains, and only two isolates were
assigned to group 4. The cases of abortion were caused by neuropathogenic
strains that also circulate within the horse population with no documented
outbreaks of disease. It was evident that strain virulence is not solely
accountable for the development of clinical symptoms in affected animals. Neural
tissue is significant for virus latency and reactivation, considering the number
of EHV-1 isolates from apparently healthy stressed horses. Special care must be
taken when accommodating together immunologically naive and latently infected
horses since asymptomatic carriers silently shed EHV-1.
To Cite This Article:
Radalj A, Milić N, Stevanović O, Veljović L and Nišavić J, 2021.
Genetic characterization of equine herpesvirus 1 from clinical cases and
asymptomatic horses in Serbia and Bosnia and Herzegovina. Pak Vet J,
41(4): 567-573. http://dx.doi.org/10.29261/pakvetj/2021.062