DNA-REPLICATION OF CHIMERIC JC VIRUS SIMIAN-VIRUS-40 GENOMES

The ubiquitous virus JCV is the etiologic agent of the human brain dis ease progressive multifocal leukoencephalopathy. Although infection us ually occurs early in life and the virus can remain latent in human ti ssues, including brain, little information is available regarding its replication. It is known that DNA replication of primate polyomaviruse s is dependent upon the synthesis of T antigen and the subsequent inte ractions of this protein with cellular factors and the viral origin of replication. We constructed chimeric genomes between JCV and SV40, tw o genetically similar viruses with distinct biologies, in which segmen ts of the T antigen coding region and the replication origin were exch anged. Because the engineering of these genomes created a defect in th e structural protein VPI, their DNA replicating activities could be co mpared without the complication of secondary infection of adjacent cel ls and amplification of the replication signal. The ability of the JCV -SV40 hybrid T antigens to initiate replication from the two viral ori gins in primate cells was investigated. A region of the JCV T antigen that includes the DNA binding and zinc finger domains was found to be responsible for the failure of JCV T antigen to interact productively with the SV40 origin. In addition, the ability to replicate in monkey cells was limited to constructs expressing T antigens which contained the carboxy-terminal host range domain of SV40. (C) 1994 Academic Pres s, Inc.