On the Association of Virus Proteins with the Nuclei of Cells Infected with Herpes Simplex Virus

In cells infected with herpes simplex virus, HSV-I, newly synthesized polypeptides accumulated in the nucleus at different rates, which did not change during the first 6 h after infection. Canavanine, an arginine analogue, prevented the nuclear accumulation of ICP (infected cell polypeptides) 5 and 8 and azetidine, a proline analogue, prevented that of ICP 5 and 7. The transfer of polypeptides to the nucleus was inhibited at 4 degrees C but not by dinitrophenol. Some of the nuclear polypeptides could be released by washing isolated nuclei with hypertonic salt solutions. ICP 17 was particularly sensitive to high salt treatment while ICP 5 and II were resistent. ICP 4b, a modified form of the alpha polypeptide ICP 4, was released by EDTA, and the detergent NP40 removed ICP II. Treatment of nuclei with DNase selectively reduced the amount of bound alpha polypeptides ICP 4c (the second modified form of ICP 4), 0 and 27 as well as ICP 8 and 25. Nuclei isolated from infected or uninfected cells and incubated in labelled cytoplasmic extracts took up primarily ICP 8 and 32. Alpha polypeptides were taken up to a lesser extent and ICP 6 and 10 were excluded. It is concluded that affinities for various constituents of host cell nuclei are likely to determine the nuclear accumulation of specific virus polypeptides.