2a. rt-PCR assays for the detection of T4 and MS2 bacteriophages. The criteria to be addresses regarding ICs were: (i) to monitor all steps of the diagnostic procedure (extraction, RT, PCR); (ii) to be amenable for DNA and RNA viruses ; (iii) to rely on a detection system specific of the phage(s) to avoid complex molecular constructs; (iv) to be usable in either simplex or multiplex format, and in one-step or two-step RT-PCR reactions.