Characterization of a host range mutant of human adenovirus 12 defective in early region 1B.

We isolated an adenovirus 12 early region 1B mutant (in206B) by ligation of the cleaved DNA-protein complex and transfection of human embryo kidney cells with the ligation products. By deduction from the DNA sequencing analysis, the two polypeptides (with molecular weights of 19,000 and 54,000) coded in the early region 1B were fused in this mutant to produce a large polypeptide. This mutant could replicate efficiently in 293 cells but not efficiently in KB or human embryo kidney cells. In KB cells, viral DNA replication could not be detected after infection with in206B. In human embryo kidney cells, viral DNA replication did occur, but the transition of viral mRNA patterns from early to late did not occur even after DNA replication, resulting in failure to produce the late polypeptides. These results indicate that the early region 1B products may be involved in both viral DNA replication and regulation of transcription.