Coping with New Virus Risks in the Manufacture of Biologics
14th April 2011
By: Dr Daniel Galbraith, CSO
In June 2009 a new virus was added to the growing list of agents found contaminating Chinese Hamster Ovary cells used in the manufacture of Biologics. Genzyme reported a contamination of CHO bioreactor with Vesivirus (subsequently named 2117); this was the third time such infection of a bioreactor had occurred in Genzyme. This virus which caused the outbreak has similarities to those previously described isolated from dogs and mink, unusual animals to be linked to a CHO bioreactor. Identifying the original source of the contaminant still remains elusive; often the source remains unidentified, bovine serum once a common supplement to cell culture growth medium has been linked to many contamination events. Cache Valley virus was the culprit in a major contamination, a virus spread by mosquitos to herds of cows and subsequently into the CHO bioreactor via bovine serum supplements. Since the introduction of serum free medium this risk has been eliminated but contamination is still a problem. The lists of viruses which have been shown to infect these bioreactors in the past include other Parvoviruses, Herpes and Bunyaviruses. Manufactures can put in place various molecular amplification methods to detect these viruses and then await the next contaminant and repeat the process; locking the stable door after the horse has bolted. However rather than reacting to each new threat and retrospectively putting in place measures to detect contamination should the industry move to a more proactive approach where a panel of tests are widened from the current panel to include tests for families of viruses? Technology is already available which can identify families of virus; this can be used as a risk based approach to screen harvests. Biologics (in contrast to blood derived products) are recognised as being safe and with many safeguards in place already to prevent the introduction of a pathogen to patients. Low cost tests to identify broad families of viruses using PCR techniques by testing bulk harvests should be the norm.