CHO-S antibody titers >1 gram/liter using flow electroporation-mediated transient gene expression followed by rapid migration to high-yield stable cell lines.

In recent years, researchers have turned to transient gene expression (TGE) as an alternative to CHO stable cell line generation for early-stage antibody development. Despite advances in transfection methods and culture optimization, the majority of CHO-based TGE systems produce insufficient antibody titers for extensive use within biotherapeutic development pipelines. Flow electroporation using the MaxCyte STX Scalable Transfection System is a highly efficient, scalable means of CHO-based TGE for gram-level production of antibodies without the need for specialized expression vectors or genetically engineered CHO cell lines. CHO cell flow electroporation is easily scaled from milligram to multigram quantities without protocol reoptimization while maintaining transfection performance and antibody productivity. In this article, data are presented that demonstrate the reproducibility, scalability, and antibody production capabilities of CHO-based TGE using the MaxCyte STX. Data show optimization of posttransfection parameters such as cell density, media composition, and feed strategy that result in secreted antibody titers >1 g/L and production of multiple grams of antibody within 2 weeks of a single CHO-S cell transfection. In addition, data are presented to demonstrate the application of scalable electroporation for the rapid generation of high-yield stable CHO cell lines to bridge the gap between early- and late-stage antibody development activities.

Development of a HTRF kinase assay for determination of Syk activity.

Regulation of protein phosphorylation is a primary cellular signaling mechanism. Many cellular responses to internal and external events are mitigated by protein kinase signaling cascades. Dysfunction of protein kinase activity has been linked to a variety of human pathologies, in the areas of cancer, inflammation, metabolism, cell cycle, apoptosis, as well as cardiovascular, neurodegenerative and autoimmune diseases. As such, there is an important need for protein kinase activity detection methodologies for researchers engaged in Drug Discovery. A number of different technologies have been employed for the measurement of protein kinase activity, including radioactive methods, luminescent methods, and fluorescent methods. More recently, Homogeneous Time Resolved Fluorescence technology (HTRF), based on the principle of time-resolved fluorescent resonance energy transfer (TR-FRET), has been developed and applied for the measurement of protein kinase activity in vitro. This technology note describes the development of an HTRF assay for detection of Syk enzyme activity in a format consistent with the requirements of High-Throughput Screening (HTS) campaigns currently used in drug discovery.

Immune responses to the major capsid protein during parvovirus infection of rats.

Rat virus (RV) is a common parvovirus of laboratory rodents which can disrupt rat-based research. Prenatal or perinatal infection can be pathogenic or lead to persistent infection, whereas infection of adult rats is typically self-limiting. Effects on the host immune system have been documented during RV infection, but little is known about immune responses necessary for viral clearance. Our studies were conducted to identify humoral and cellular responses to the predominant capsid protein, VP2, during experimental infection of adult rats. We observed VP2-specific proliferation, gamma interferon production, and an immunoglobulin G2a humoral response that is maintained for at least 35 days following RV infection. These results strongly suggest the induction of virus-specific Th1-mediated immunity.