Regulation of varicella zoster virus gene 27 translation in vitro by upstream sequences

Northern blot analysis revealed the presence of varicella-zoster virus (VZV) gene 27 transcripts in infected cells. The SalI-G DNA fragment, located in the unique long segment of the VZV genome and containing overlapping genes 26 and 27, was analyzed in an in vitro transcription-translation system. Translation of RNA transcribed from these open reading frames showed prominent expression of gene 27. Four different subclones were constructed to contain gene 27 with and without 100 base pairs (bp) of upstream sequences. Translation of RNA from these constructs using wheat germ extract or rabbit reticulocyte lysate indicated that the sequences upstream from the predicted intiation codon (AUG) of gene 27 downregulated the expression of this gene at the level of translation and that the predicted AUG within gene 27 was preferentially used.