Newly identified transcripts of UL4 and UL5 genes of human cytomegalovirus.

Human cytomegalovirus (HCMV) UL4 and UL5 genes are two members of the RL11 gene family. In an earlier study, three UL4 transcripts of about 1.7, 1.5 and 1.4 kb were found in early and late classes after infection by the Towne strain by nuclease protection and primer extension analyses. In the present study, two UL4 transcripts (1.5 and 1.7 kb) were found by cDNA library screening, Northern blot, 3' and 5' RACE analyses to appear initially in the immediate early phase and one UL4 transcript (1.4 kb) in the late phase in a low-passage clinical isolate. Furthermore, two novel low-abundance UL5 transcripts with the same 3' terminus as the identified UL4 transcripts in the UL4-UL5 gene region were found in late class RNAs.