The immediate-early mRNA that encodes the regulatory polypeptide Vmw 175 of herpes simplex virus type 1 is unspliced.

Abstract
The structure and precise map location of the 4.1‐kb herpes simplex virus type 1 (HSV‐1) immediate‐early mRNA (IE mRNA‐3) that encodes a regulatory polypeptide, with an approximate mol. wt. of 175 000, has been determined. Nuclease S1 digestion procedures using labelled virus DNA probes have shown that IE mRNA‐3 is unspliced and maps entirely within the TRs/IRs genome regions. DNA sequences at the 5′ and 3′ ends of IE mRNA‐3 have been examined and regulatory signals involved in initiation of transcription and polyadenylation have been identified. No other mRNA is known to map within the region coding for IE mRNA‐3.