G47Δ precludes down-regulation of MHC class I expression in infected
host cells. (a) Flow cytometric analyses of MHC class I
expression in Detroit 551 human fibroblast cells 48 h after
infection with HSV-1 (moi = 3). Whereas all HSVs with an intact
α47 gene (wild-type strain F and G207)
significantly down-regulated MHC class I expression, G47Δ completely
precluded the down-regulation. (b) Time course of MHC
class I down-regulation in Detroit 551 cells infected with HSV-1. For
each virus, the peak value of MHC class I expression at 6, 24, or
48 h after infection, as analyzed by flow cytometry, was expressed
as a percentage of the peak value of mock-infected cells (Control) at
each time point. MHC class I down-regulation by G207 and R3616 occurred
in a time-dependent fashion. Dissociation of MHC class I expression
between α47-deleted mutants (G47Δ and
R47Δ) and α47-intact viruses became
apparent at 24–48 h after infection. (c) Flow
cytometric analyses of MHC class I expression in human melanoma cell
lines 24 h after infection with G207 and G47Δ. G47Δ caused a
partial preclusion of MHC class I down-regulation in melanomas 1102 and
938, resulting in greater MHC class I expression than G207.