Bacterial Retention During Filtration of a Live Attenuated Virus Vaccine Through the Sartobran P Sterile Filter

Recent studies of sterile filtration of a Live Attenuated Virus (LAV) demonstrated that the Sartobran P sterile filter provided 80% yield of a LAV that was 100 - 400 nm in size, raising questions about the effectiveness of this filter in retaining the standard challenge bacterium, Brevundimonas diminuta. This study evaluated the retention of B. diminuta by the Sartobran P over a range of conditions appropriate for LAV filtration. The B. diminuta were characterized by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), and scanning electron microscopy. The Sartobran P showed complete retention of B. diminuta under all conditions, even in the presence of additives like sucrose, surfactants, and high salt that have previously been hypothesized to increase the risk of bacterial breakthrough. The size of B. diminuta decreased when incubated in the nutrient poor media required by the ASTM challenge test. The addition of sucrose caused a further reduction in size as measured by NTA, although this was due to an increase in cell motility. There was no evidence of bacterial breakthrough at high loadings of either the LAV or B. diminuta, further demonstrating the effectiveness of the Sartobran P for sterile filtration of large viral vaccines.