Issues related to harmonization of testing requirements for viral safety.

The current situation concerning the development of an internationally harmonized document on the technical requirements for the viral safety of biotechnology drugs (ICH viral safety document) is described. Major issues relating to harmonization of testing requirements for viral safety include: (i) clarification of scientific rationale; (ii) the way and extent of virus tests for cell line qualification and cell cultivation process evaluation; (iii) discussion of the scope, extent and frequency of virus testing on the unprocessed bulk harvest; (iv) discussion of the choice of viruses for virus clearance evaluation or process characterization study.