A Working Virus Seed Stock (WVSS) is a cryopreserved collection of a specific virus or viral vector derived directly from the Master Virus Seed Stock (MVSS), prepared in multiple aliquots and used as the direct starting material for individual viral vector manufacturing campaigns. Analogous to the Working Cell Bank (WCB) in cell-based manufacturing, the WVSS preserves the integrity of the master stock by serving as the routine production source, and must meet defined quality specifications for identity, purity, potency, titer, and absence of adventitious agents in compliance with GMP guidelines and regulatory requirements from agencies such as the European Medicines Agency (EMA) and Food and Drug Administration (FDA).
