A virus seed stock is a well-characterized, cryopreserved collection of a specific virus or viral vector — produced from a defined starting material under controlled conditions — that serves as the primary reference source for all subsequent viral manufacturing campaigns. Analogous to the Master Cell Bank (MCB) in cell-based manufacturing, virus seed stocks are established at two levels: the Master Virus Seed Stock (MVSS) and the Working Virus Seed Stock (WVSS), both of which must meet defined quality specifications for identity, purity, potency, titer, and absence of adventitious agents, in compliance with GMP guidelines and applicable regulatory requirements from agencies such as the European Medicines Agency (EMA) and Food and Drug Administration (FDA).
