The purpose of this study is to investigate the effect of steady-state concentrations of TMC435 on the steady-state pharmacokinetics of TMC278 or Tenofovir , 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. TMC278 and Tenofovir are two antiretroviral drugs for treatment of human deficiency virus (HIV) infection. Pharmacokinetics (pk) means how the drug is absorbed into the bloodstream, distributed in the body and eliminated from the body.