In order to clarify the biological role of US2 gene product of herpes simpl
ex virus type 2 (HSV-2), a HeLa cDNA library was screened,in the yeast two-
hybrid system using US2 protein as bait, and several interacting proteins w
ere identified, including cytokeratin 18. US2 protein was co-immunoprecipit
ated with cytokeratin 18 from HSV-2 infected cell lysates. Analysis of infe
cted or A431 cells by immunofluorescence showed that US2 protein gave filam
entous or dot-like cytoplasmic staining pattern, and that it co-localized w
ith cytokeratin 18. When US2 protein was expressed alone, it co-localized w
ith cytokeratin 18. To define the domain interacting with cytokeratin 18, d
eletion mutant proteins were constructed and cells transfected with mutants
were analyzed by indirect immunofluorescence. These results suggest that t
he N-terminal half of the US2 protein, especially the region containing ami
no acids 42-77, is important for interaction with cytokeratin 18.