NUCLEOTIDE-SEQUENCE ANALYSIS OF AN INFECTIOUS LARYNGOTRACHEITIS VIRUSGENE CORRESPONDING TO THE US3 OF HSV-1 AND A UNIQUE GENE ENCODING A 67-KDA PROTEIN

The DNA sequence of 4005 nucleotides from the Kpnl O and part of Kpnl K fragments in the short unique region of infectious laryngotracheitis virus (ILTV) was determined. The sequence contained two complete and one partial open reading frames (ORFs). The partial ORF was open at th e 5' end of the sequence and represented the NH2-terminal 118 amino ac ids (aa) of a polypeptide. Its partial predicted protein product exhib ited significant homology to the US2 gene product of HSV-1 (herpes sim plex virus type 1) and its homologs in other herpesviruses. ORF 2 is 4 71 aa long and could encode a protein of 53.8 kDa which shared aa homo logy with the protein kinases encoded by HSV-1 US3 and its gene homolo gs. Analysis of the ORF 2 aa sequence revealed domains characteristic of protein-serine!threonine (S/T) kinases of cellular and viral origin . The ORF 3 encoded a predicted protein of 601 aa (Mr 67.5 kDa) which exhibited limited homology (18% overall identity) with the UL47 protei n (major tegument protein) of HSV-1. Northern (RNA) blot hybridization and metabolic inhibitors were used to characterize the ILTV protein k inase and the 67K mRNAs. The data revealed that protein kinase is a ga mma-1 gene encoding a 1.6 kb mRNa, while the 67K ORF is a gamma-2 gene encoding a 2 kb mRNA.