How to review the virus testing report before purchasing fetal bovine serum?

If the supplier only provides a project list but the methods are vague, I will request supplementary method numbers or references, such as referencing 9 CFR 113.53 or the pharmacopoeia, and confirm that the batch number on the COA matches the actual vial label. For PCR-negative results, I suggest checking the primer coverage of subtypes; for BVDV, it is necessary to distinguish between type 1 and type 2; for cell culture methods, it is best to use sensitive cells such as MDBK/BT and perform blind passages. For single-batch retention samples, I usually retain an amount sufficient for two repeat tests; viral nucleic acid testing plus virus isolation requires approximately 30–50 mL, aliquoted into small volumes and stored frozen at −80°C to avoid repeated freeze-thaw cycles. Whether to send samples for third-party retesting depends on whether the supplier already has an international third-party report and whether the batch is intended for critical preclinical use.

For FBS used in recombinant protein applications, the supplier's COA should at minimum clearly state the test methods, detection limits, and blind passage generations. The virus panel should generally cover BVDV, BPV, Reo-3, PI3, BRSV, adenovirus, and parvovirus; some suppliers also include bovine herpesvirus or bovine enterovirus. A negative PCR result only indicates that nucleic acid was not detected; it does not mean there are no low-titer infectious particles. For cell culture methods, it is necessary to check which cells were inoculated, whether 2–3 blind passages were performed, and whether positive controls were included. It is recommended that after receiving the report, you perform a gap analysis according to your document system, retain at least 10–20 mL from the original unopened bottle per lot for aliquoting, and do not pool samples before sending them for third-party verification.

For CHO cell feed development, CHO may not necessarily be the most sensitive host for bovine viruses such as BVDV, but regulatory submissions and audits place greater emphasis on the documentation chain rather than cytopathic effects alone. It is recommended to compare the supplier's COA item by item against the previous lot, with particular attention to whether the testing laboratory or method has been changed. If the COA only shows a negative BVDV PCR result without cell culture isolation, I would consider the evidence chain incomplete and would at least require supplementary cell culture assays for BVDV and parvovirus. Regarding retention samples, in addition to the quantity needed for testing, retain approximately 20 mL of unopened original vial samples to facilitate traceability in the event of deviations. Third-party retesting can serve as a supplement to supplier audits, but it is best to use the same sample and specify on the testing request form that the vial must not be opened for sampling.

At a minimum, routine items such as BVDV, PI3, IBR, and adenovirus must be included; do not rely solely on the certificate of conformity stamp.

The report depends on the testing method and limits, which vary greatly between different manufacturers.