Comparative sequence and phylogenetic analysis of open reading frame 30 (ORF30) of neuropathogenic and non-neuropathogenic EHV-1 strains from the united states and france

EHV-1 than EHV-4 with 96% and 88% deduced amino acid identities respectively. Like EHV-4, AHV-3 contained a D at the 752 amino acid position equivalent. Even among the most closely related equid alphaherpesviruses, the maintenance of EHV-1 with a DNA polymerase containing N752 is unique and suggests a relatively recent evolution. Despite the increasing number of outbreaks of neuropathogenic EHV-1 in the US and Europe in the last decade, this disease manifestation and associated SNP remain less common than EHV-1 abortions and detection of EHV-1 containing a DNA pol with N752. There may be many reasons for apparent fitness advantage of these viruses, including their relative transmissibility that may be greater from high titred aborted foetal tissue compared to levels of virus shed in the respiratory tract.