The invention relates to generic methods for the detection and quantification of mammalian reoviruses. These may uses a reverse transcription (RT-PCR) real time (q-PCR) assay which amplifies a conserved region within all MRV types. The assays allow the quantification of MRV RNA molecules, irrespective of the particular virus type (e.g. MRV-1, MRV-2). The methods are particularly applicable in the monitoring of vaccine production processes.