Twenty plus Years of Data Demonstrating Virus Filtration as an Effective and Robust Step for Large Virus Removal.

Virus filtration has been demonstrated to be an effective and robust dedicated viral clearance step that is used in biopharmaceutical manufacturing processes. Here we present virus filtration data from a multicompany collaboration with data compiled from WuXi Advanced Therapies' and Charles River Laboratories' internal viral clearance databases spanning more than 25 years. The data were sorted by virus removal and type and then further subdivided into murine leukemia virus only, pseudorabies virus only, and reovirus type 3 only categories to allow for analyses of viral clearance results. A total of 2311 virus filtrations were analyzed, composed of 1516 murine leukemia virus, 385 pseudorabies virus, and 410 reovirus type 3 virus filtrations. These data provide clear evidence that will help supplement both internal and industry-wide initiatives focused on using prior knowledge for the creation of modular claims for small virus retentive filters and allow better allocations of resources typically spent on potentially unnecessary studies.

Comparison of human memory CD8 T cell responses to adenoviral early and late proteins in peripheral blood and lymphoid tissue.

Treatment of invasive adenovirus (Ad) disease in hematopoietic stem cell transplant (SCT) recipients with capsid protein hexon-specific donor T cells is under investigation. We propose that cytotoxic T cells (CTLs) targeted to the late protein hexon may be inefficient in vivo because the early Ad protein E3-19K downregulates HLA class I antigens in infected cells. In this study, CD8+ T cells targeted to highly conserved HLA A2-restricted epitopes from the early regulatory protein DNA polymerase (P-977) and late protein hexon (H-892) were compared in peripheral blood (PB) and tonsils of naturally infected adults. In tonsils, epitope-specific pentamers detected a significantly higher frequency of P-977+CD8+ T cells compared to H-892+CD8+ T cells; this trend was reversed in PB. Tonsil epitope-specific CD8+ T cells expressed IFN-γ and IL-2 but not perforin or TNF-α, whereas PB T cells were positive for IFN-γ, TNF-α, and perforin. Tonsil epitope-specific T cells expressed lymphoid homing marker CCR7 and exhibited lower levels of the activation marker CD25 but higher proliferative potential than PB T cells. Finally, in parallel with the kinetics of mRNA expression, P-977-specific CTLs lysed targets as early as 8 hrs post infection. In contrast, H-892-specific CTLs did not kill unless infected fibroblasts were pretreated with IFN-γ to up regulate HLA class I antigens, and cytotoxicity was delayed until 16-24 hours. These data show that, in contrast to hexon CTLs, central memory type DNA polymerase CTLs dominate the lymphoid compartment and kill fibroblasts earlier after infection without requiring exogenous IFN-γ. Thus, use of CTLs targeted to both early and late Ad proteins may improve the efficacy of immunotherapy for life-threatening Ad disease in SCT recipients.