Equine herpesvirus type 1 strain Kentucky A: Characterization of unique short genes and assessment of pathogenicity in the mouse model

The EHV-1 genome of the Kentucky A strain is 144 kbp in size and is composed of a unique long (UL) region and a short region containing inverted repeat (IR) segments that bracket a unique short (Us) segment. Sequence analysis of the Us segment revealed six major open reading frames designated EUS1 to EUS5 and EUS9. The predicted EUS2 gene product has homology to the serine/threonine family of protein kinases. The EUS3 and EUS4 genes appear to encode putative glycoproteins (gp) that are homologs of gpX of pseudorabies virus and a unique gp, respectively. The Us region of EHV-1 has a complex pattern of transcription with many overlapping transcripts. At early times of infection, a 2.9 kb transcript is detected that encodes the protein kinase (PK). A second early transcript of 1.6 kb appears at 4 hours and encodes the gpX homolog. Mapping of the transcriptional initiation site indicates that both transcripts are 3...