Herpes simplex virus ICP27 induces cytoplasmic accumulation of unspliced polyadenylated alpha-globin pre-mRNA in infected HeLa cells

Transcripts of most intron-bearing cellular genes must be processed by the splicing machinery in order to efficiently accumulate and gain access to th e cytoplasm. However, we found that herpes simplex virus induces cytoplasmi c accumulation of both spliced and unspliced polyadenylated alpha-globin RN As in infected HeLa cells. Accumulation of the unspliced RNA required the i mmediate-early protein ICP27, and ICP27 was sufficient (in combination with ICP4) to produce this effect in a transient-transfection assay. However, e xpression of ICP27 did not markedly alter the levels of fully spliced alpha -globin transcripts in infected cells. These data demonstrate that the prev iously documented effects of ICP27 on the cellular splicing apparatus do no t greatly inhibit splicing of alpha-globin RNA and argue that ICP27 induces a splicing-independent pathway for alpha-globin RNA accumulation and nucle ar export.