The purpose of this study is to investigate the effect of steady-state concentrations of TMC435 150mg q.d. (once a day) on the steady-state pharmacokinetics of escitalopram 10 mg q.d., and vice versa. Steady state is a term which means that the drug has been given long enough so that the plasma concentrations will remain the same with each subsequent dose. TMC435 is being investigated for the treatment of chronic hepatitis C virus (HCV) infection. Pharmacokinetics (pk) means how the drug is absorbed into the bloodstream, distributed in the body and eliminated from the body.