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Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the virus responsible for the ongoing pandemic of Coronavirus Disease 2019 (COVID-19). Other members of the enveloped RNA virus family Coronaviridae have been responsible for a variety of human diseases and economically important animal diseases. Disinfection of air, environmental surfaces, and solutions is part of infection prevention and control (IPAC) for such viruses and their associated diseases. This article reviews the literature on physical inactivation (disinfection) approaches for SARS-CoV-2 and other coronaviruses. Data for thermal (heat) inactivation, gamma irradiation, and ultraviolet light in the C range (UVC) irradiation have been reviewed. As expected, the susceptibilities of different members of the Coronaviridae to these physical inactivation approaches are similar. This implies that knowledge gained for SARS-CoV-2 should be applicable also to its emerging mutational variants and to other future emerging coronaviruses. The information is applicable to a variety of disinfection applications, including IPAC, inactivation of live virus for vaccine or laboratory analytical use, and waste stream disinfection. more...

FT819 is a first-of-kind, allogeneic, off-the-shelf CAR T-cell therapy derived from a clonal master induced pluripotent stem cell (iPSC) line precisely engineered to insert a novel 1XX anti-CD19 chimeric antigen receptor (CAR) under the regulation of the T-cell receptor alpha constant (TRAC) locus for optimized control of anti-tumor activity and to completely delete T-cell receptor (TCR) expression to eliminate the potential of graft-versus-host disease (GvHD). Unlike conventional allogeneic CAR T-cell therapies which require repeatedly sourcing of T cells from various donors as the starting material, the use of a clonal master engineered iPSC line serves as a renewable starting cell source and ensures routine mass production of a uniformly engineered, homogenous CAR T-cell product for broad patient access. T cell-derived iPSCs were generated using a proprietary non-integrating cellular reprogramming system and genetically modified to integrate a novel anti-CD19 1XX CAR into both alleles of the TRAC gene. After single cell subcloning, each engineered iPSC clone was screened for multiple critical quality attributes including pluripotency, identity, genomic stability, cassette integration, on/off-target integration, T-cell differentiation propensity, and CAR T-cell function. Accordingly, the ideal single cell-derived engineered iPSC clone was selected as the clonal master iPSC line for FT819 and was converted into a master cell bank (MCB). The iPSC MCB serves as a renewable source for the routine GMP manufacture of FT819 drug product. The FT819 production process consists of three stages: 1) generation of CD34-expressing hematopoietic progenitor cells from iPSCs (>90% CD34+ cells post enrichment); 2) lineage-specification to T cells followed by T-cell expansion (>5e5 fold expansion); and 3) fill/finish and cryopreservation of the drug product. As an example, in an initial small-scale manufacturing campaign, a total of 2.5 × 10 10 FT819 CAR T-cells were generated and filled and finished starting from one vial of the MCB. The FT819 drug product was tested on safety, identity, purity, and potency. The final product was comprised of CD45+CD7+ lymphocytes (>99%), with homogeneous CAR expression (>99% CAR+) and lacking expression of TCRαβ (not detected) on the cell surface. Importantly, there were no residual iPSCs detected in the FT819 drug product. The FT819 drug product exhibited potent and consistent effector function against NALM6 leukemia cells. The FT819 drug product is currently being used in a landmark Phase I study (NCT04629729), the first-ever iPSC-derived T-cell therapy to undergo clinical investigation, for the treatment of patients with relapsed/refractory B-cell lymphoma, chronic lymphocytic leukemia and precursor B-cell acute lymphoblastic leukemia. In summary, FT819 is a first-of-kind, off-the-shelf, CAR T-cell therapy uniquely derived from a clonal multiplexed-engineered master iPSC line. The novel manufacturing paradigm enables mass production of a uniformly engineered, homogenous cell therapy product that is available on-demand for broad patient access. A multi-center Phase 1 study of FT819 is currently ongoing for the treatment of B-cell malignancies. Key Words: cancer immunotherapy, cell therapy, CAR-T, CD19, allogeneic, induced pluripotent stem cell, iPSC, clonal master iPSC line, engineered, off-the-shelf, cGMP, production, manufacturing, FT819 Disclosures Yuan: Fate Therapeutics, Inc.: Current Employment. Clarke: Fate Therapeutics, Inc.: Current Employment. Lai: Fate Therapeutics, Inc.: Current Employment. Chang: Fate Therapeutics, Inc.: Current Employment. Yang: Fate Therapeutics, Inc.: Current Employment. Hsia: Fate Therapeutics, Inc.: Current Employment. Abujarour: Fate Therapeutics, Inc.: Current Employment. Lee: Fate Therapeutics, Inc.: Current Employment. van der Stegen: Fate Therapeutics, Inc.: Current Employment. Shaked: Fate Therapeutics, Inc.: Current Employment. Jalloh: Fate Therapeutics, Inc.: Current Employment. Moreno: Fate Therapeutics, Inc.: Current Employment. ORourke: Fate Therapeutics, Inc.: Current Employment. Sung: Fate Therapeutics, Inc.: Current Employment. Gutierrez: Fate Therapeutics, Inc.: Current Employment. Rezner: Fate Therapeutics, Inc.: Current Employment. Eberhart: Fate Therapeutics, Inc.: Current Employment. Magdaleno: Fate Therapeutics, Inc.: Current Employment. Farnan: Fate Therapeutics, Inc.: Current Employment. Plavsic: Fate Therapeutics, Inc.: Current Employment. Bressi: Fate Therapeutics, Inc.: Current Employment. Rivière: Centre for Commercialization of Cancer Immunotherapy: Other: Provision of Services; Fate Therapeutics: Other: Provision of Services, Patents & Royalties; The Georgia Tech Research Corporation (GTRC): Other: Provision of Services (uncompensated); FloDesign Sonics: Other: Provision of Services; Juno Therapeutics: Patents & Royalties. Valamehr: Fate Therapeutics, Inc.: Current Employment. more...

Vesivirus 2117 (VV-2117) has been recently described as a contaminant of cell culture operations in several biologics manufacturing facilities. VV-2117 has been poorly studied and little information exists about its biology, pathogenicity and infectivity range in cell culture settings. In this study we evaluated the potential in vitro viral infectivity of VV-2117 using a range of established mammalian cell lines from various species, the effectiveness of virus amplification in CHO-K1 cells at differing infection levels, and the relative sensitivity of two test methods (cytopathic effect [CPE] and polymerase chain reaction [PCR]) to detect infection and viral amplification. Of eight cell culture systems studied, two originating from hamster (CHO-K1 and BHK-21) and one from canine (MDCK) were positive for CPE and also showed a marked increase of viral RNA in a reverse transcriptase quantitative PCR (RT-qPCR) test. CHO-K1 cell cultures inoculated at 10, 1 and 0.1 genome copies per cell (gc/cell) showed both CPE and amplification of VV-2117 RNA, indicating that infection had occurred in these cultures. CHO-K1 cultures inoculated at 0.01, 0.001, 0.0001 and 0.00001 gc per cell showed neither CPE nor VV-2117, indicating that infection had not occurred. Therefore, the minimum dose necessary for infection of CHO-K1 cells was approximately 0.1 genome copies per cell. At any infection level where VV-2117 amplification was observed by RT-qPCR, the cultures also showed CPE. There was no low-level infection that could be detected by RT-qPCR without developing signs of CPE. However, the RT-qPCR assay appeared more sensitive in that it detected VV-2117 infection earlier than the onset of observable CPE. more...

Recombinant protein therapeutics, vaccines, and plasma products have a long record of safety. However, the use of cell culture to produce recombinant proteins is still susceptible to contamination with viruses. These contaminations cost millions of dollars to recover from, can lead to patients not receiving therapies, and are very rare, which makes learning from past events difficult. A consortium of biotech companies, together with the Massachusetts Institute of Technology, has convened to collect data on these events. This industry-wide study provides insights into the most common viral contaminants, the source of those contaminants, the cell lines affected, corrective actions, as well as the impact of such events. These results have implications for the safe and effective production of not just current products, but also emerging cell and gene therapies which have shown much therapeutic promise. more...

The prevention of adventitious agent contamination is a top priority throughout the entire biopharmaceutical production process. For example, although viral contamination of cell banks or cell cultures is rare, it can result in serious consequences (e.g., shutdown and decontamination of manufacturing facilities). To ensure virus free production, numerous in vivo and in vitro adventitious agent assays and biophysical characterizations such as electron microscopy are conducted on cell banks, raw materials, process materials, and drug substances throughout the manufacturing process. Molecular assays such as PCR and other nucleotide-based techniques are also routinely used for screening and identification of any viral agents. However, modern techniques in protein identification of complex protein mixtures have not yet been effectively integrated throughout the industry into current viral testing strategies. Here, we report the identification and quantitation of Vesivirus 2117 particles in bioreactor fluid from infected Chinese hamster ovary cell cultures by global protein sequencing using mass spectrometry in combination with multi-dimensional liquid-chromatography. Following mass spectrometric data acquisition and rigorous data analysis, six virus specific peptides were identified. These peptides were fragments of two structural proteins, capsid protein pre-cursor (four unique peptides) and small structural protein (two unique peptides), from the same species: Vesivirus 2117. Using stable heavy isotope-labeled peptides as internal standards, we also determined the absolute concentration of Vesivirus particles in the bioreactor fluid and the ratio of two capsid proteins (VP1:VP2) in the particles as approximately 9:1. The positive identification of Vesivirus 2117 was subsequently confirmed by RT-PCR. more...

The utility of electron beam as a physical approach for viral inactivation has been investigated to a limited extent, particularly for food safety and for applications for which other irradiation approaches such as gamma irradiation have produced unsatisfactory results or adverse impacts on the irradiated material. Viral inactivation by electron beam and gamma irradiation is mechanistically similar, though dose rate and penetrability into the irradiated material differ between the two approaches. In this paper, we have summarized the available data on the efficacy of electron beam for viral inactivation and the few studies that have directly compared the efficacy of electron beam and gamma irradiation for viral inactivation. more...

Next-generation sequencing has been evaluated at Genzyme as a means of identifying bioreactor contaminants due to its capability for detection of known and novel microbial species. In this approach, data obtained from next-generation sequencing is used to interrogate databases containing genomic sequences and identities of potential adventitious agents. We describe here the use of this approach to help identify the causative agent of a bioreactor contamination. We also present the results of spiking experiments to establish the limits of detection for DNA viruses, RNA viruses, and bacteria, in a background of Chinese hamster ovary cells, a cell line used for production of many human therapeutics. Using Illumina sequencing-based detection, all of the viruses included in this study were detected at less than 1 copy per cell, and bacteria were detected at 0.001 copy per cell. Thus, next-generation sequencing–based detection of adventitious agents is a valuable approach that can fill a critical unmet need in the detection of known and novel microorganisms in biopharmaceutical manufacturing. LAY ABSTRACT: Because biological products are manufactured in cells, the living environment must be kept sterile. Any introduction of microorganisms into the culture vessel may affect the growth and other biological properties of the cells or contaminate the product. It is therefore important to monitor the culture for such contaminants, but many methods can only detect a specific microorganism. In this study, we show that next-generation sequencing–based detection is a sensitive and complementary approach that can potentially detect a wide range of organisms. more...

A systematic review of the viral heat inactivation literature for data compatible with modeling using the decimal reduction value/z value approach as well as a new approach based on the power function relationship between decimal reduction value and inactivation temperature is presented. The review has enabled us to conduct quantitative intra-family and inter-family comparisons for various heat inactivation characteristics for viruses, including z value, temperature in°C for 1 log10 and for 4 log10 inactivation in 30 seconds. The parvoviridae family is confirmed to be the most heat resistant of the various virus families for which data were analyzed. more...

Polyomavirus inactivation has been studied since the 1950s when it became apparent that certain polio vaccines were contaminated with SV40. Relatively high temperatures (≥70 °C) are required to effect thermal inactivation of the polyomaviruses. The chemical inactivants that are effective (β-propiolactone, ethanol, sodium hydroxide, and formaldehyde) are those that have displayed efficacy for other small, non-enveloped viruses, such as the circoviruses. Low pH inactivation can be effective, especially at pH at or below 3 and at higher temperatures. Polyomaviruses are more resistant to UV-C irradiation than are other small non-enveloped viruses such as the parvoviruses and caliciviruses. The efficacy of photodynamic inactivation of polyomaviruses is very much dye-dependent, with toluidine blue, acridine orange, and methylene blue dyes being effective photosensitizers. Ionizing radiation can be effective, depending on the conditions employed and the inactivation matrix. Inactivation of the oncogenic properties of the polyomaviruses may require higher doses of inactivant than those required to inactivate infectivity. While the polyomaviruses are considered to be highly resistant to inactivation, the degree of resistance is dependent upon the specific approach under consideration. For certain approaches, such as UV-C and gamma-irradiation, the polyomaviruses appear to be more resistant than other small non-enveloped viruses. more...

Animal-derived materials such as animal sera represent a low, but finite, risk for introduction of an adventitious agent (virus or mollicute) into a biological bulk harvest during upstream manufacturing processes involving mammalian cell substrates. Viral and mollicute (Mycoplasma sp. and Acholeplasma sp.) contamination events have been relatively rare, but many of those that have been reported have been attributed to use of infected animal sera in growth media during cell expansion. The risk of introduction of viruses and mollicutes may be mitigated by elimination of the use of animal sera and implementation instead of chemically defined or serum- and animal-derived material-free cell culture media. When use of animal sera is unavoidable, however, mitigation of the risk of introducing an adventitious contaminant may involve treatment of the sera to inactivate potential contaminants. Gamma irradiation is one of the most widely employed methods for viral and mollicute inactivation in animal sera. In this article, we review the inactivation results reported for viral and mollicute inactivation in frozen serum. Studies performed to assess the impact of gamma irradiation on serum quality and performance are also discussed. The available data indicate that inactivation of mollicutes in serum is essentially complete at the gamma radiation doses normally employed (25–40 kGy), while the efficacy and kinetics for viral inactivation in serum by gamma irradiation appear to be dependent in part upon the size of the target virus. more...

The potential inadvertent introduction of viral or prion agents into the biopharmaceutical production environment has accelerated technical and regulatory actions to ensure biosafety. Primary efforts have focused upon three activities: (a) Validated processing of essential animal-derived medium constituents to eradicate adventitious contaminants; (b) Design and qualification of protein-free, biochemically-defined nutrient formulations without animal origin constituents; and (c) Improved manufacturing process controls to validate sanitization and ensure against cross-contamination. more...