IN-SITU HYBRIDIZATION AND IMMUNOELECTRON MICROSCOPE ANALYSES OF THE US11 GENE OF HERPES-SIMPLEX VIRUS TYPE-1 DURING TRANSIENT EXPRESSION

The distribution of Us11 RNA and of its encoded protein have been inve stigated at the ultrastructural level in HeLa cells transiently expres sing the Us11 gene of herpes simplex virus type 1. In these transfecte d cells, Us11 protein accumulates at sites identical to those of lytic ally infected cells, i.e., in nucleoli and in regions of the cytoplasm that contain ribosomes. Us11 RNA and polyadenylated RNA are scattered over the ribosome-rich areas of the cytoplasm. They also accumulate i n the nucleoplasm on clustered ribonucleoprotein (RNP) fibrils but als o in clusters of interchromatin granules, some of them contiguous to n ucleoli. However they are never found in nucleoli. These data reveal t he involvement of interchromatin granules in some steps of Us11 mRNA m aturation and/or transport.