The complete genome of equid herpesvirus-1 (EHV-1) field isolates from Argentina reveals an interspecific recombinant strain.

The Equid alphaherpesvirus type 1 (EHV-1) infection can have devastating economic consequences in the horse industry due to large-scale outbreaks of abortions, perinatal foal mortality, and myeloencephalopathy. The present study analyzed the genome of two isolates obtained from aborted fetuses in Argentina, E/745/99 and E/1297/07. The E745/99 genome shares 98.2% sequence identity with Ab4, a reference EHV-1 strain. The E/1297/07 genome shares 99.8% identity with NY03, a recombinant strain containing part of ORF64 and part of the intergenic region from Equid alphaherpesvirus-4 (EHV-4). The E/1297/07 genome has the same breakpoints as other United States and Japanese recombinants, including NY03. The recombinant regions have varying numbers of tandem repeat sequences and different minor parental sequences (EHV-4), suggesting distinct origins of the recombinant events. These are the first complete genomes of EHV-1 from Argentina and South America available in the Databases.

Comprehensive Analysis of Equid Herpesvirus Recombination: An Insight Into the Repeat Regions.

High-throughput sequencing of genomes has expanded our knowledge of the Alphaherpesvirinae, a widely extended subfamily of DNA viruses that recombine to increase their genetic diversity. It has been acknowledged that equid herpesvirus 1 (EHV-1) and equid herpesvirus 4 (EHV-4), two alphaherpesviruses with an economic impact on the horse industry, can recombine. This work aimed to analyze interspecific recombination between all equid alphaherpesvirus species, using genomes of EHV-1, EHV-3, EHV-4, EHV-6, EHV-8, and EHV-9 available in GenBank. 14 events of recombination by RDP4 and Simplot between EHV-1 x EHV-4, EHV-1 x EHV-9, EHV-8 x EHV-1, and EHV-8 x EHV-9 were identified. Ten out of 14 events involved ORF64, a double-copy gene located at the repeat regions that codifies for the infected cell protein 4 (ICP4). Among the ICP4, recombination can be found between EHV-1 X EHV-9, EHV-8 X EHV-9, and EHV-1 X EHV-4, the former affects zebra-borne genotypes, a type of EHV-1 that infect wild equids, and the latter match with previous breakpoints reported in fields isolates. Consequently, these findings strongly suggest that ICP4 is a hotspot for recombination. This work describes novel recombination events and is the first genome-wide recombination analysis using all available equid alphaherpesvirus species genomes.