ESTABLISHMENT AND CHARACTERIZATION OF A CARRIER CELL-CULTURE PRODUCING HIGH TITERS OF POLYOMA JC VIRUS

This report concerns a carrier cell culture (designated JCI) infected persistently with JC virus (JCV). Immunostaining with an anti-JCV anti serum revealed that JCI was a carrier culture in which only a small fr action of the cells (similar to 1.5%) produced the virus. The JCV titr e was increased strikingly by incubating confluent JCI cells for 4-6 d ays in medium containing a low concentration of fetal bovine serum (2% ). Viral genomes cloned from the persistently infected JCI cells were heterogeneous with respect to size, but most clones had an alteration of the same regulatory region (designated CR-JCI). Transfection experi ments with a chimeric JCV DNA (Mad-ii CR-JCI), in which the regulatory region was CR-JCI and the other region was derived from an infectious JCV (Mad-1) DNA, showed that CR-JCI was less efficient in inducing vi ral growth than the regulatory regions of lMR-32-adapted JCVs. The tra nsfected cells could be readily subcultured, and they continued to pro duce JCV. It is concluded that a decrease in the activity of the JCV r egulatory region is of importance for the maintenance of the carrier s tate of JCI cells. (C) 1995 Wiley-Liss, Inc.