IMMEDIATE-EARLY GENE-EXPRESSION AND GENE-MAPPING COMPARISONS AMONG ISOLATES OF BOVINE HERPESVIRUS-1 AND HERPESVIRUS-5

Bovine herpesviruses (BHV) are associated with a variety of clinical s yndromes. Bovine herpesvirus 1 isolates were placed into three genome subtypes based on restriction endonuclease analyses, which were loosel y associated by clinical manifestation as BHV1.1 (respiratory), BHV1.2 (genital), and BHV1.3 (encephalitic). More recently the encephalitic isolate has been classified BHV5. A comparison of the cytopathic effec t (CPE) in fetal bovine lung cell cultures in the presence of cyclohex imide showed that BHV 1.1 and 1.2 isolates produced elongated, spindle -shaped CPE, whereas BHV5 produced more syncytial-like CPE. Each BHV-1 subtype synthesized four immediate-early transcripts. The sizes in kb were: 1.6, 3.4, 5.8, 7.5 (BHV1.1); 1.8, 3.6, 5.8, 7.5 (BHV1.2); and 1 .8, 3.6, 5.8, 8.6 (BHV5). These transcripts were mapped to the inverte d repeat region of each isolate by Southern blot hybridization using c DNA prepared from cycloheximide-treated BHV1-infected cellular polyA R NA. A possible unique immediate-early RNA may be produced by the BHV5 encephalitic isolate from an area of the internal repeat region unique to this isolate. Hybridization analysis using BHV1.1 cloned probes of the immediate-early protein gene, thymidine kinase gene, DNA binding/ DNA polymerase gene, and glycoprotein III gene provided information fo r mapping of these genes to the BHV5 encephalitic isolate.