SUBCELLULAR-LOCALIZATION OF THE US3 PROTEIN-KINASE OF HERPES-SIMPLEX VIRUS TYPE-2

One supposes that herpes simplex virus US3 gene product possessing ser ine/threonine protein kinase activity is a cytoplasmic enzyme. To dete rmine its subcellular localization during viral replication we prepare d an antiserum to a synthetic oligopeptide corresponding to the N-term inal region of the US3 protein of HSV type 2 strain 186. The US3 prote in first appeared in the cytoplasm of infected cell at 4 h postinfecti on but strong fluorescence was detected in the nuclei at 8 h postinfec tion. At 12 h postinfection fluorescence was mainly detected in the cy toplasm, again. Further, the US3 protein expressed alone was widely di stributed throughout the cell, indicating that the US3 protein by itse lf can be localized in the nuclei even in the absence of any other vir al proteins. These observations suggest that the HSV-2 US3 protein kin ase may function not only in the cytoplasm but also in the nuclei.