Lentiviral titer determination: rapid & robust molecular methods suitable for validation
Cell & Gene Therapy Insights 2022; 8(11), 1163–1172
High-quality recombinant lentiviral vectors (LVV) are key for transgene delivery in many cell and gene therapies, including several of the FDA-approved CAR-T cell products. Critical to the success of these biologics are reliable methods to characterize and quantitate LVV. This article provides an overview of quality attributes, regulatory expectations, and challenges in LVV titer determination and characterization. Quantitation of total genome-containing particles and infectious particles is valuable to optimize the vector production process and to appropriately dose for cell transduction at the desired multiplicity of infection. Vector copy number is also a critical quality attribute to assess the integration and safety of transduced cell products. Two qPCR assays are described that enable quantitation and correlation of total and infectious lentivirus particles designed to facilitate LVV analytics in process development and manufacturing quality control.