I would like to perform an in-house multiplex real time PCR for analyzing the viral gene expression in some virus infected patient samples. I am not sure about using internal control or housekeeping genes such as RNP. I would like to control both quantity of the expression and working of my reaction. In this case do you think using housekeeping gene will be sufficient for both analyses or should I go on with internal control? If housekeeping gene expression varies for each patient can I still use it as a reference gene for the reaction generally? Also would it be logical to use some housekeeping gene belonging human genome for normalizing my viral gene expression? And finally, If I have to use internal control how should I design it?