Transfected RTG-2 cells infected with VHSV showed significant induction of the
luciferase reporter gene, compared to the control non-infected cells, at 24, 48 and
72 h post infection (p.i.). The maximum expression was recorded at 72 h p.i. (2.25
folds compared to the control cells). In these cells, the infection with IPNV and
EHNV did not result in the luciferase expression at any time tested. In transfected
CHSE-214 cells, EHNV stimulated luciferase expression at 24 h p.i. (2.17 folds
compared to the control cells), whereas cells infected with IPNV and VHSV did
not show luciferase activity at any time. The lack of induction of the SsMx
promoter after VHSV infection in CHSE-214 cells, as well as after EHNV
infection in RTG-2 cells may be caused by viral IFN-suppression mechanisms, as
has been demonstrated for IPNV in previous studies. Furthermore, the different
induction of the SsMx promoter observed in RTG-2 and CHSE-214 cells after
infection with the same virus indicates that cellular specific factors are involved in
the IFN-signaling response. Therefore, the use of two different cellular systems
might be an interesting approach to identify such cellular factors.