Genetic characterization of equid herpesvirus type 1 from cases of abortion in Poland

Abstract

Equid herpesvirus type 1 (EHV-1) is a common viral infection associated with varied clinical outcomes including respiratory disease, abortion and neurological disease. We have characterized EHV-1 sequences (n = 38) obtained from cases of equine abortion in Poland between 1999 and 2016, based on sequencing of PCR products from open reading frames (ORF) 30 and 68 of the EHV-1 genome. The majority (81.6%) of sequences were not classified into any of the previously described groups based on the ORF68 sequence. The remaining sequences belonged to ORF68 group III (7.9%) or IV (10.5%). A haplotype network analysis did not show any obvious structure within networks of local Polish sequences, nor within a global network of 215 EHV-1 sequences when these networks were coloured based on the geographical origin of viruses or date of detection. Our data suggest that ORF68 does not provide a reliable molecular marker for epidemiological studies of EHV-1, at least in a global sense. Its usefulness to aid local investigations of individual outbreaks remains to be established. All but two Polish EHV-1 sequences belonged to the ORF30 N752 genotype. The two ORF30 D752 viruses were obtained from abortion cases in 2009 and 2010. Hence, abortion cases that occurred in Poland between 1999 and 2016 were caused predominantly by EHV-1 with the ORF30 N752 genotype, with no indication of an increase in the prevalence of the ORF30 D752 variant.Electronic supplementary materialThe online version of this article (doi:10.1007/s00705-017-3376-3) contains supplementary material, which is available to authorized users.

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

“…More than half of the EHV-1 sequences (57.7%) contained A 629 SNP. Ten Polish EHV-1 sequences (38.5%) possessed the same substitutions (A 629 and T 750 ) as the EHV-1 sequence of GB86_3_2, which was described as an unassigned sequence in the original study by Nugent et al [ 12 ] and Polish EHV-1 sequence PL_1999_II from a recent study by Stasiak et al [ 18 ]. Three sequences had the same SNPs (A 629 , C 626 and T 750 ) as sequence PL_2013_V, while two sequences were similar to PL_2001_I from the Stasiak et al [ 18 ] (Figs.…”

“…Typical nucleotide positions for each groups [ 12 ] are highlighted. Asterisk: ORF68 sequences described in [ 18 ]. Dots represent the same nucleotide sequence.…”

“…In this study, none of the EHV-1 strains isolated from aborted fetuses between 1993 and 2017 belonged to the neuropathogenic genotype D 752 , and all belonged to the non-neuropathogenic variant N 752 . In two recent studies conducted in Poland, the neuropathogenic variant D 752 was found in 2 out of 20 cases (10%) and in none out of 37 (0%) EHV-1 isolates obtained from abortion cases [ 18 , 20 ]. In those studies, Polish D 752 EHV-1 strains were isolated in the years 2009 and 2010.…”

“…In those studies, Polish D 752 EHV-1 strains were isolated in the years 2009 and 2010. Our study includes older isolates than previous Polish studies done by Stasiak et al [ 18 , 20 ]. Summarizing all the analyses so far, on Polish EHV-1 sequences from years 1993 to 2017, the prevalence of the neuropathogenic genotype D 752 is very low, only 3.07% (2/65 EHV-1).…”

“…Chromatograms obtained from sequencing were manually checked for errors with FinchTV software. The fragments of ORF68 sequences obtained were aligned with a ClustalW algorithm, with a set of representative sequences of each group from the original Nugent et al 2006 study [ 12 ] and a recent Polish study Stasiak et al [ 18 ] obtained from GenBank with MEGA7.1 software [ 19 ]. The ORF68 sequences obtained in this study were subjected to GenBank under the accession numbers MH329902-H329927.…”