Choristoneura fumiferana multiple nucleopolyhedrovirus LEF-3-P143 complex can complement DNA replication and budded...

Transient replication assays using Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Choristoneura fumiferana multiple nucleopolyhedrovirus (CfMNPV) genes suggested that the interactions between P143, the viral helicase and LEF-3, a ssDNA-binding protein, may represent virus species specificity determinants. P143 and LEF-3 are essential for DNA replication in these assays and together with IE-1, the major immediate-early transcription factor, may be part of the viral replisome. In the current report, a lef-3/p143 double-knockout AcMNPV bacmid was constructed that was defective for viral DNA replication and late gene expression. When the homologous lef-3/p143 CfMNPV genes were introduced into this double-knockout bacmid, DNA replication was restored but the level of replication was lower, budded virus production was delayed, and the yields were reduced from those in an AcMNPV-rescue bacmid. These results suggest that to maximize virus replication, baculovirus replisome assembly and function requires protein-protein interactions between P143 and LEF-3, and other viral proteins.