Viral contamination is a common risk to continuous cell line-derived biologics. Viral validation is thus required for license applications. Viral validation for chromatography procedures is routinely performed by spiking a model virus into the load material and performing the chromatography procedures at small scale under conditions equivalent to the commercial scale. With traditional cell-based infectivity assays, one can only spike one model virus at one time. Quantitative PCR methods (TaqMan) make it possible to spike multiple model viruses for a chromatography procedure simultaneously. TaqMan assays can quantify multiple types of viruses and other types of nucleic acid in a single sample without cross interference because of its extremely high specificity. Therefore, a multivirus spike approach was evaluated and compared to a single virus spike approach. The study was further extended to the evaluation of host cell DNA clearance. The data shows highly comparable viral and host cell DNA clearance between the single and multiple virus spike approaches. Application of a multivirus spike approach provides significant time, manpower, and cost savings for new drug development. (C) 2003 Wiley Periodicals, Inc.