Poster Presentation 8th Australasian Virology Society Meeting and 11th Annual Meeting of the Australian Centre for Hepatitis & HIV Virology Meeting 2015

Equid herpesvirus 1 in New Zealand (#128)

Magdalena Dunowska 1 , Gaya Gopakumar 1 , Matthew R. Perrott 1 , Anna T. Kenndal 1 , Sununta Waropastrakul 1 , Carol A. Hartley 2 , Harry B. Carslake 3
  1. Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Palmerston North, New Zealand
  2. Centre for Equine Virology, School of Veterinary Science, University of Melbourne, Melbourne, Australia
  3. School of Veterinary Science, University of Liverpool, Liverpool, UK

Objectives: Equid herpesvirus (EHV) type 1 is an enveloped DNA virus classified within the family Alphaherpesviridae in the order Herpesvirales [1]. It is genetically and antigenically similar to EHV-4. Infection with equid herpesvirus 1 (EHV-1) may be asymptomatic, or may result in respiratory disease, abortion, neonatal death, or neurological disease referred to as equine herpesvirus myeloencephalopathy (EHM) [2, 3]. Recently, an amino acid substitution from asparagine (N) to aspartic acid (D) at amino acid position 752 of the viral DNA polymerase has been associated with increased neurovirulence [4]. The aim of this study was to estimate the prevalence of EHV-1 infection, including differentiation between D752 and N752 genotypes, within a selected population of New Zealand horses. The second aim was to determine the predictive value of serology for detection of latently infected horses.

Methods: Retropharyngeal lymph nodes (RLN) and trigeminal ganglia (TG) were dissected from 52 horses at slaughter and tested for the presence of EHV-1 DNA using magnetic bead, sequence-capture enrichment followed by nested PCR. Sera were tested for EHV-1 antibody using type-specific glycoprotein G ELISA.

Results and Conclusions: Overall, 17/52 horses tested positive for EHV-1 DNA. All but one positive PCR results were obtained from RLN samples. Fifteen of the EHV-1 positive horses harboured EHV-1 with N752 genotype, one of which was additionally infected with the D752 genotypes of the virus [5]. Our data comprise the first detection of EHV-1 with D752 genotype in New Zealand and suggest that this variant of EHV-1 had been present in New Zealand for at least two years before the first reported outbreak of EHM. All sampled horses tested positive for EHV-4 antibody, and 11/52 tested positive for EHV-1 antibody. The strength of agreement between results of EHV-1 PCR and EHV-1 serology was “fair” (Kappa 0.259, 95% CI: −0.022–0.539).

  1. Davison, A.J., et al., The order Herpesvirales. Arch Virol, 2009. 154(1): p. 171-7.
  2. Dunowska, M., A review of equid herpesvirus 1 for the veterinary practitioner. Part B: Pathogenesis and epidemiology. NZ Vet J, 62(4):179-88, 2014.
  3. Dunowska, M., A review of equid herpesvirus 1 for the veterinary practitioner. Part A: Clinical presentation, diagnosis and treatment. NZ Vet J, 62(4):171-8, 2014.
  4. Goodman, L.B., et al., A point mutation in a herpesvirus polymerase determines neuropathogenicity. PLoS Pathog, 2007. 3(11): p. e160.
  5. Dunowska, M., et al., Virological and serological investigation of Equid herpesvirus 1 infection in New Zealand. Vet Microbiol, 2015. 176(3-4): p. 219-28.