TEMPORAL REGULATION OF HERPES-SIMPLEX VIRUS TYPE-1 UL24 MESSENGER-RNAEXPRESSION VIA DIFFERENTIAL POLYADENYLATION

Using Northern blot, primer extension, and S1 nuclease analyses of wil d-type and deletion-containing herpes simplex type 1 viruses, we found that UL24 sequences are contained in six different transcripts that o riginate from three previously identified mRNA start sites. Thus, the six UL24 transcripts represent three different pairs of 5' coterminal mRNAs. Each transcript pair consists of a short species whose 3' end c orresponds to a polyadenylation signal located just downstream of the UL24 open reading frame, and a longer species whose 3' end corresponds to a polyadenylation signal located downstream of the UL26 gene. Maxi mal accumulation of the short UL24 transcripts was at early times duri ng infection, while accumulation of the longer species did not decreas e at late times. Consistent with early kinetics, the short transcripts were less sensitive to drugs that inhibited viral DNA replication tha n the longer transcripts which exhibited leaky-late kinetics. Quantita tive S1 nuclease analysis indicated that 3' ends corresponding to the UL24 polyadenylation site were significantly more abundant at early ti mes than at late times. Thus, differential polyadenylation determines the kinetics of accumulation of different UL24 transcripts. (C) 1996 A cademic Press, Inc.