HSV-1-inducible proteins bind to NF-κB-like Sites in the HSV-1 genome

Abstract

Several putative NF-κB-binding sites in the ICPO and Vmw65 herpes simplex virus type-1 (HSV-1) genes have been identified. Oligonucleotides encoding some of these sites bind specifically to purified NF-κB protein and an NF-κB-like protein in nuclear extracts of phorbol ester- or cycloheximide-induced human embryonic lung (HEL) cells. HSV-1 infection of HEL cells induced a nuclear factor that binds specifically to κB sites in the ICPO and Vmw65 gene regions and comigrates with complexes formed by purified NF-κB. The HSV-1-inducible nuclear factor bound to the authentic immunoglobulin (Ig) κB site. Transient expression of chloramphenicol acetyltransferase (CAT) plasmids containing two copies of the Ig κB site upstream of the c-fos promoter (KB2CAT) showed little activity in HEL cells. HSV-1 infection of κB 2-CAT-transfected HEL cells, however, induced a dramatic increase in CAT activity; mutation in the NF-κB-binding site of κB 2CAT abolished the inducibility of CAT gene expression. Our results demonstrate that the HSV-1 ICPO and Vmw65 gene regions contain binding sites for NF-κB, and that HSV-1-inducible proteins bind to NF-κB-like sites in the HSV-1 genome.