Scientific Publications by FDA Staff
Gene Ther 2013 Jan;20(1):43-50
Rapid titration of retroviral vectors using a beta-lactamase protein fragment complementation assay.
Ou W, Marino MP, Lu C, Reiser J
The availability of rapid and quantitative titration assays for retroviral vectors is important, especially in the context of clinical applications. In this report, we describe a novel assay to titrate lentiviral and gamma retroviral vectors. This rapid assay is based on protein fragment complementation involving the N-terminal (Bla1) and the C-terminal (Bla2) fragments of TEM-1 beta-lactamase (BLAK). The Bla1 protein fragment is incorporated in the vector's envelope during vector production. Bla1-bearing vectors are titrated on Bla2-expressing cells. Upon transduction, Bla1 and Bla2 heterodimerize and restore BLAK's enzymatic function. The enzymatic activity of BLAK is quantified by flow cytometry using the green fluorescent CCF2/AM substrate, which is converted into a blue fluorescent product. The enzymatic conversion of the CCF2/AM substrate was found to be directly related to vector entry, as a neutralizing antibody completely blocked the conversion. The titers obtained using this rapid assay correlated well with the titers measured by functional transduction assays. The whole assay can be finished within 8 h. Thus, it is considerably less time consuming compared with other transduction-based titration assays for lentiviral and gamma retroviral vectors.
|Category: Journal Article|
|PubMed ID: #22257933||DOI: 10.1038/gt.2011.212|
|Includes FDA Authors from Scientific Area(s): Biologics|
|Entry Created: 2012-01-21||Entry Last Modified: 2013-05-15|