INFECTIOUS LARYNGOTRACHEITIS HERPESVIRUS EXPRESSES A RELATED PAIR OF UNIQUE NUCLEAR PROTEINS WHICH ARE ENCODED BY SPLIT GENES LOCATED AT THE RIGHT END OF THE U-L GENOME REGION

Avian infectious laryngotracheitis virus (ILTV) possesses an alphaherp esvirus type D DNA genome of ca. 155 kbp. Completion of our previous s equence analyses (W. Fuchs and T. C. Mettenleiter, J. Gen. Virol. 77:2 221-2229, 1996) of the right end of the unique long (U-L) genome regio n revealed the presence of two adjacent, presumably ILTV-specific gene s, which were named UL0 and UL[-1] because of their location upstream of the conserved UL1 (glycoprotein L) gene. Transcriptional analyses s howed that both genes are abundantly expressed during the late phase o f the viral replication cycle and that both mRNAs are spliced by the r emoval of short introns close to their 5' ends. Furthermore, the deduc ed gene products exhibit a moderate but significant homology of 28% to each other. The newly identified ILTV genes encode proteins of 63 kDa (UL0) and 73 kDa (UL[-1]), which both are predominantly localized in the nuclei of virus infected chicken cells. In summary, our results in dicate that duplication of a spliced ILTV-specific gene encoding a nuc lear protein has occurred during evolution of ILTV.