Establishing a surrogate model for inactivation of enveloped viruses to
screen viral clearance conditions during biotherapeutics process
development
Abstract
Viral surrogates to screen for virus inactivation (VI) can be a faster,
cheaper and safer alternative to third-party testing of pathogenic BSL2
(Biosafety Level 2) model viruses. Although the bacteriophage surrogate,
Ø6, has been used to assess low pH BSL2 VI, it has not been used for
evaluation of detergent-mediated VI. Furthermore, Ø6 is typically
assayed through host cell infectivity which introduces the risk of
cross-contaminating other cell lines in the facility. To circumvent
contamination, we developed an in-house RT-qPCR (reverse transcriptase
quantitative polymerase chain reaction) assay for selective detection of
active Ø6 from a population of live and dead phage. The RT-qPCR assay
was used to evaluate Ø6 inactivation in cell culture fluid of monoclonal
antibody and fusion protein. Complementary Ø6 infectivity was also
conducted at a third-party testing facility. The Ø6 RT-qPCR and
infectivity data was modeled against VI of three BSL2 viruses, X- MuLV,
A- MuLV and HSV-1 in corresponding therapeutics. Both Ø6 methods
demonstrate that any VI agent showing Ø6 clearance of ≥ 2.5 logs would
demonstrate complete BSL2 VI of ≥ 4.0 logs. Compared to BSL2 virus
testing, this in-house Ø6 RT-qPCR tool can screen VI agents at 5% the
cost and a turnaround time of 2-3 days versus 4-7 months.