Molecular characterisation of equid alphaherpesvirus 1 strains isolated from aborted fetuses in Poland

BACKGROUND: Equid alphaherpesvirus 1 (EHV-1) is one of the main infectious causative agents of abortion in mares and can also be associated with stillbirth, neonatal foal death, rhinopneumonitis in young horses and a neurological disorder called equine herpesvirus myeloencephalopathy (EHM). The neuropathogenicity of the virus was shown to be significantly higher in EHV-1 strains that carry a single nucleotide point (SNP) mutation in the ORF30, which encodes a catalytic subunit of viral DNA polymerase (ORF30 D(752)). Another gene, ORF68 is frequently used for phylogenetic analysis of EHV-1. METHODS: 27 EHV-1 strains isolated from aborted equine fetuses in Poland, collected between 1993 and 2017, were subjected to PCR targeting the open reading frames (ORFs) 30 and 68 of the EHV-1 genome. PCR products obtained were sequenced and SNPs were analyzed and compared to sequences available in GenBank. RESULTS: None of the analyzed sequences belonged to the ORF30 D(752)neuropathogenic genotype: all EHV-1 belonged to the non-neuropathogenic variant N(752). On the basis of ORF68 sequences, the majority of EHV-1 sequences (76.9%) cannot be assigned to any of the known groups; only six sequences (23.1%) clustered within groups II and IV. CONCLUSIONS: EHV-1 strains obtained from abortion cases belong to the non-neuropathogenic genotype. Many EHV-1 ORF68 sequences have similar SNPs to those already described in Poland, but a clear geographical distribution was not observed. A single particular ORF68 sequence type was observed in strains isolated from 2001 onwards. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12985-018-1093-5) contains supplementary material, which is available to authorized users.