Leveraging vectored vaccine candidates manufacturing to GMP compatible bioprocesse

Background Vectored vaccines are very efficient in the in vivo delivery of antigens either in the form of antigen protein and peptides or genetic material. The bioprocess of vectored vaccines poses however several challenge since the viral particles to be effective must maintain their infectivity. Lentiviral and adenoviral vectors are among the particles more used in the treatment of cancer diseases modulating the immune system. Both viral vectors are currently produced in transient upstream process. While the adenoviral vectors are produced at high titers the lentiviral vector upstream process still requires further improvement. The non-lytic nature of lentivirus enables the design of stable cell lines which may improve its yields through perfusion and longer term productions, reducing costs. The application of novel methods for the downstream processing such as continuous purification will contribute to increase the yield and lower the overall cost of the manufacturing processes. Experimental approach At the upstream process, many of the challenges lentiviral bioproducts present in its manufacturing are related to the apoptosis-leading cytotoxicity of some of the vector components. Supported on our long track experience and enabling tools developed for gammaretrovirus manufacturing, we undertook the challenge of establishing a constitutive stable lentiviral producer cell line. To address this challenge we proposed to eliminate or reduce the cytotoxicity of the lentiviral vector expression components. At the downstream process lentiviral vectors face the challenges common to retroviridae family of vectors namely short half-lives at room temperature, sensitivity to pH variations and salt concentrations, and shear stress. The purification strategy developed was designed to be based on disposable and easily scalable technologies. A final concentration achieving 108 TU mL-1 was targeted since the concentration step itself allows to reduce the burden on process and improve the transduction efficiency. To address the high doses requirements we will report an improved oncolytic adenovirus purification process for phase I and II clinical trials and present a case on the use of Polysorb 20 as a replacement for Triton X-100 during cell lysis. Product recovery, potency, purity and the effect of manufacturing holding points will be discussed. Results and discussion A lentiviral producer cell line constitutively producing titers above 106 TU.mL-1.day-1 was established. The cell line showed to be stable, consistently maintaining vector productivity over one month in the absence of antibiotics. At the bioreaction process it was possible to maintain the cells continuously producing over 10 days. At downstream we implemented scalable protocols for lentiviral and adenoviral vectors that is easy to transfer to GMP environment, combining microfiltration, anion-exchange, and ultrafiltration membranes technologies toward maximization of infectious virus recovery, allowing generation of clinical-grade viral vectors without the need for cleaning validation in a cost-effective manner. Herein we will present and discuss the challenges on the biomanufacturing of lentiviral as well as adenoviral virus, the strategies and novel technologies to be adopted in order to enable a faster development of novel vectored vaccine candidates focusing on several case studies, supported by process technology innovation

Expression of IMP1 Enhances Production of Murine Leukemia Virus Vector by Facilitating Viral Genomic RNA Packaging

Murine leukemia virus (MLV)-based retroviral vector is widely used for gene transfer. Efficient packaging of the genomic RNA is critical for production of high-titer virus. Here, we report that expression of the insulin-like growth factor II mRNA binding protein 1 (IMP1) enhanced the production of infectious MLV vector. Overexpression of IMP1 increased the stability of viral genomic RNA in virus producer cells and packaging of the RNA into progeny virus in a dose-dependent manner. Downregulation of IMP1 in virus producer cells resulted in reduced production of the retroviral vector. These results indicate that IMP1 plays a role in regulating the packaging of MLV genomic RNA and can be used for improving production of retroviral vectors

Site-specific recombinases for manipulation of the mouse genome.

Site-specific recombination systems are widespread and popular tools for all scientists interested in manipulating the mouse genome. In this chapter, we focus on the use of site-specific recombinases (SSR) to unravel the function of genes of the mouse. In the first part, we review the most commonly used SSR, Cre and Flp, as well as the newly developed systems such as Dre and PhiC31, and we present the inducible SSR systems. As experience has shown that these systems are not as straightforward as expected, particular attention is paid to facts and artefacts associated with their production and applications to study the mouse genome. In the next part of this chapter, we illustrate new applications of SSRs that allow engineering of the mouse genome with more and more precision, including the FLEX and the RMCE strategies. We conclude and suggest a workflow procedure that can be followed when using SSR to create your mouse model of interest. Together, these strategies and procedures provide the basis for a wide variety of studies that will ultimately lead to the analysis of the function of a gene at the cellular level in the mouse

Enhancement of antibody production by the addition of Coenzyme-Q10

Recently, there has been a growing demand for therapeutic monoclonal antibodies (MAbs) on the global market. Because therapeutic MAbs are more expensive than low-molecular-weight drugs, there have been strong demands to lower their production costs. Therefore, efficient methods to minimize the cost of goods are currently active areas of research. We have screened several enhancers of specific MAb production rate (SPR) using a YB2/0 cell line and found that coenzyme-Q10 (CoQ10) is a promising enhancer candidate. CoQ10 is well known as a strong antioxidant in the respiratory chain and is used for healthcare and other applications. Because CoQ10 is negligibly water soluble, most studies are limited by low concentrations. We added CoQ10 to a culture medium as dispersed nanoparticles at several concentrations (Q-Media) and conducted a fed-batch culture. Although the Q-Media had no effect on cumulative viable cell density, it enhanced SPR by 29%. In addition, the Q-Media had no effect on the binding or cytotoxic activity of MAbs. Q-Media also enhanced SPR with CHO and NS0 cell lines by 30%. These observations suggest that CoQ10 serves as a powerful aid in the production of MAbs by enhancing SPR without changing the characteristics of cell growth, or adversely affecting the quality or biological activity of MAbs

Non-viral gene delivery strategies for gene therapy: a “ménage à trois” among nucleic acids, materials, and the biological environment

Gene delivery is the science of transferring genetic material into cells by means of a vector to alter cellular function or structure at a molecular level. In this context, a number of nucleic acid-based drugs have been proposed and experimented so far and, as they act on distinct steps along the gene transcription-translation pathway, specific delivery strategies are required to elicit the desired outcome. Cationic lipids and polymers, collectively known as non-viral delivery systems, have thus made their breakthrough in basic and medical research. Albeit they are promising alternatives to viral vectors, their therapeutic application is still rather limited as high transfection efficiencies are normally associated to adverse cytotoxic side effects. In this scenario, drawing inspiration from processes naturally occurring in vivo, major strides forward have been made in the development of more effective materials for gene delivery applications. Specifically, smart vectors sensitive to a variety of physiological stimuli such as cell enzymes, redox status, and pH are substantially changing the landscape of gene delivery by helping to overcome some of the systemic and intracellular barriers that viral vectors naturally evade. Herein, after summarizing the state-of-the-art information regarding the use of nucleic acids as drugs, we review the main bottlenecks still limiting the overall effectiveness of non-viral gene delivery systems. Finally, we provide a critical outline of emerging stimuli-responsive strategies and discuss challenges still existing on the road toward conceiving more efficient and safer multifunctional vectors