FLAG adenovirus

Adenoviruses are non-enveloped icosahedral viruses with a linear double-stranded DNA genome of approximately 36 kilobases, belonging to the Adenoviridae family. Human adenovirus type 5 (HAdV5) is the most thoroughly studied member and a widely used gene delivery vector because of its ability to efficiently transduce both dividing and non-dividing cells in various tissues. In recombinant vector form, deletion mutations of early genes, such as the E1 gene (used to prevent replication in normal cells) and the E3 gene (used to increase payload capacity without affecting production in complementary cell lines), can be introduced to create a replication-deficient system that supports high levels of transgene expression while improving safety. Adenoviral vectors typically exist as episomes in the host cell nucleus, resulting in robust but transient expression, with expression levels peaking rapidly (usually within days), making them ideal for short-term functional studies, rapid screening, and proof-of-concept experiments.

A FLAG adenovirus based on HAdV5 with E1/E3 deletion mutations and a CMV promoter-driven expression cassette provides a versatile, ready-to-use control reagent for experiments relying on protein tagging workflows for precise detection and benchmarking. The FLAG epitope (DYKDDDDK) is one of the most widely used short tags in molecular biology and is supported by highly validated monoclonal antibodies and standardized detection protocols. This control virus expresses only the FLAG tag via a strong CMV promoter, providing a consistent high-signal benchmark for experiments such as immunofluorescence microscopy, Western blotting, flow cytometry, ELISA, and immunoprecipitation/co-immunoprecipitation, allowing users to confirm antibody performance, set exposure parameters, and assess detection sensitivity and background in their target cell environment. It is particularly valuable for calibrating infection multiplicity in different cell types or difficult-to-transduce primary cells, standardizing detection thresholds across different experiments, and distinguishing true epitope-dependent signals from non-specific binding signals.