title: Evaluation of adenoviral vectors by flow cytometry.
abstract: Biological assays for adenoviral gene therapy vectors have included conventional procedures initially developed to detect wild-type adenoviruses. Standard virological assays to quantitate adenoviruses rely on the virus to infect and replicate in the host cell until a cytopathic effect is observed. The appearance of plaques, colonies of rounded, enlarged cells containing infectious virions, usually takes 2 to 3 weeks to reach an endpoint. We describe a flow cytometric bioassay for adenovirus which shortens the time from when the infection takes place to the time that biological titer is determined. A fluorescent focus-forming assay was one of the first rapid adenoviral bioassays developed. Virus titer was determined using fluorescence immunocytochemistry to detect adenovirus proteins and microscopy to count fluorescent foci in cultures of adenovirus-infected cells. In this study, we describe a flow cytometric assay performed on cells stained for adenovirus hexon capsid protein, where virus titer is determined based on the dose-dependent appearance of hexon-positive cells. Adenovirus hexon detection in infected cells can provide data to determine virus titer, inducible promoter function in vector-complementing cells, and vector replication in complementation-deficient cells.
authors.affiliation: Genetic Therapy, Inc., 9 West Watkins Mill Road, Gaithersburg, Maryland 20878, USA.
authors.forename: L S
authors.initials: LS
authors.lastname: Weaver
authors.forename: M J
authors.initials: MJ
authors.lastname: Kadan
mesh_terms: D017498:Adenovirus E1 Proteins / Q000235:genetics; D000260:Adenoviruses, Human / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*; D000956:Antigens, Viral / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D015139:Blotting, Southern; D002213:Capsid / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics; D036022:Capsid Proteins; D002460:Cell Line; D004247:DNA / Q000032:analysis; D004279:DNA, Viral / Q000032:analysis; D003907:Dexamethasone / Q000494:pharmacology; D005434:Flow Cytometry / Q000379:methods*; D005455:Fluorescent Antibody Technique; D017353:Gene Deletion; D015967:Gene Expression Regulation, Viral / Q000187:drug effects / Q000235:genetics; D005816:Genetic Complementation Test; D015316:Genetic Therapy / Q000379:methods; D005822:Genetic Vectors / Q000235:genetics*; D006801:Humans; D008856:Microscopy, Fluorescence; D011401:Promoter Regions, Genetic / Q000235:genetics; D012680:Sensitivity and Specificity; D013997:Time Factors; D014407:Tumor Cells, Cultured; D010948:Viral Plaque Assay; D014779:Virus Replication
chemical_list: D017498:Adenovirus E1 Proteins; D000956:Antigens, Viral; D036022:Capsid Proteins; D004279:DNA, Viral; C018315:hexon capsid protein, Adenovirus; D003907:Dexamethasone; D004247:DNA