Graduate Fellowship for Study and Research in Biogenetic Engineering

In an attempt to study regulation of infectious bovine rhinotracheitis virus gene expression, we chose one of the well known genes, thymidine kinase (tk) gene. The viral thymidine kinase is different from cellular TK in substrate specificities, pH and temperature optimum, etc. The TK is a beta protein and expressed only after the translation of alpha genes. In addition, in herpesvirus infection, TK activity was though to be associated with the reactivation of the disease. The direct approach to attack the problem is to clone the IBRV-tk gene followed the similar task used in the identification of HSV-tk gene by transfecting the tk-containing DNA fragment into tk defective mouse cells. But the isolation of the IBRV-tk gene was considered to be difficult due to the incapability of converting the Ltk-cells into tk+ phenotype. In this report, we took a novel approach to identify the gene and prove the gene isolated expressed as a beta group gene and encoded a message in IBRV-infected MDBK cells.