Section 18.5 refers to viral removal and viral inactivation steps, and refers to Q5A. Has FDA determined if validation of inactivation of mammalian model viruses is required for insect cell culture processes, since the growth temperature of insect cells would not allow replication of mammalian viruses, it is not appropriate though Q5A seems to imply it is?

Q5A states that insect cells are included. The issue would be identifying the potential virus in the insect cell line, then developing the appropriate methods to validate the removal and/or inactivation of those viruses. The tables that are provided as part of Q5A list the model viruses, and perhaps are a little bit biased in that they refer to the mammalian viruses, but they only serve to list those that would potentially be used for those production systems. So, your viral clearance steps and demonstration of the capability to remove the viruses in your process would really be dependent upon the cells that are used in production.