| Field | Specification |
|---|---|
| Form | Liquid |
| Function | |
| Plasmid Backbone | |
| Product Type | |
| Production System | |
| Promoter | |
| Reporter | |
| Storage |
Overview
AAV-eGFP-iCre (AAV8) AAV (AAV8-EGFP-iCre) is an AAV vector packaged in AAV8 under the CMV promoter that delivers codon-improved Cre (iCre) to mammalian cells. Researchers commonly use this vector for conditional gene knockout/activation in floxed mouse lines; lineage tracing.
Key elements and design rationale
- Capsid (serotype): AAV8. strong liver tropism upon systemic delivery; also active in muscle, CNS and retina.
- Promoter: CMV — human cytomegalovirus immediate-early promoter; strong, broadly active in most mammalian cell types.
- Payload: codon-improved Cre (iCre) — mammalian codon-optimized Cre recombinase variant with reduced CpG content and improved expression in mammalian cells.
- Genome backbone: Recombinant AAV (single-stranded unless explicitly noted as scAAV) flanked by AAV2 ITRs.
Biological background
iCre is a mammalian codon-improved variant of Cre recombinase from bacteriophage P1. The codon optimization reduces silencing in mammalian cells and increases expression relative to unmodified Cre. Cre catalyzes site-specific recombination between two 34-bp loxP sites, enabling deletion (loxP-loxP), inversion (DIO/FLEX), or activation (LSL stop cassette) of floxed gene cassettes in conditional mouse models.
AAV-delivered iCre is a widely used tool for delivering Cre activity to a specific cell population through capsid tropism and promoter selectivity, particularly when a tissue-specific Cre driver line is unavailable.
The CMV promoter — human cytomegalovirus immediate-early promoter; strong, broadly active in most mammalian cell types — drives expression of the payload from the AAV cassette in this product. Promoter–capsid combinations together determine where and at what level the payload is expressed.
Research relevance and current trends
- Cre-AAV is widely used to deliver Cre activity to brain regions or cell types without dedicated driver lines, expanding the conditional genetics toolkit.
- Combinations of intersectional approaches (Cre + Flp, or CreERT2 + tamoxifen pulses) allow finer spatial and temporal restriction of recombination.
- AAV vector engineering — including capsid evolution, capsid shuffling, and rational design — continues to expand the spectrum of accessible tissues and cell types.
Common research applications
- Conditional gene knockout in floxed mouse alleles.
- Activation of Cre-dependent reporter lines (e.g., Ai9/Ai14, Rosa-LSL-LacZ).
- Lineage tracing when delivered to a defined cell population.
Use this product within experimental designs that include matched controls (capsid, promoter, dose, route) and a transduction validation step before interpreting payload-specific phenotypes.
Notes for experimental interpretation
- Confirm transduction efficiency in the target cell population before drawing payload-specific conclusions; reporter signal alone validates only that the vector reached and expressed in the cells.
- Match AAV dose, capsid, promoter, and route across all conditions when comparing payload to control; differences in any of these confound payload-specific interpretation.
- Avoid repeated freeze–thaw cycles of AAV stocks — aliquot upon first thaw.
- AAV biology, including tropism, can differ between species, strains, ages, and routes — confirm in your specific system.
Choose an AAV capsid based on your target tissue/cell type and delivery route, then benchmark 1–2 alternative serotypes empirically. The capsid (serotype) determines surface attachment and uptake; the cassette and promoter then control where and how strongly expression occurs once cells are transduced. The reference table below summarizes well-established tropism patterns — actual transduction efficiency depends on cell type, route, dose, anti-AAV neutralizing antibodies, and species.
Serotype × tissue tropism reference
| Serotype | Primary attachment / receptor | Best-supported tissues / cells | Common use cases |
|---|---|---|---|
| AAV1 | α-2,3 / α-2,6 N-linked sialic acid | Skeletal muscle, cardiac muscle, CNS neurons, retinal pigment epithelium | Intramuscular and stereotaxic CNS injection; broad neuronal labeling |
| AAV2 | Heparan sulfate proteoglycan (HSPG); coreceptors FGFR1, HGFR | CNS neurons, retinal ganglion cells, kidney, vascular smooth muscle | Stereotaxic CNS injection; intravitreal eye delivery; standard CNS workhorse |
| AAV4 | α-2,3 O-linked sialic acid | Retinal pigment epithelium, ependymal cells of brain ventricles | Subretinal RPE labeling; intracerebroventricular ependyma transduction |
| AAV5 | α-2,3 N-linked sialic acid; PDGFR coreceptor | Airway epithelium, CNS (astrocytes prominent), retinal photoreceptors | Intratracheal lung delivery; CNS astrocyte transduction; subretinal photoreceptor |
| AAV6 | Sialic acid + HSPG; EGFR coreceptor | Skeletal muscle, cardiac muscle, lung, hematopoietic cells (incl. T cells, HSPCs) | Intramuscular delivery; ex vivo HSPC engineering; intratracheal lung |
| AAV8 | 37/67 kDa Laminin receptor (LamR) | Liver (hepatocytes), cardiac muscle, skeletal muscle, retina, pancreas | Systemic IV → liver-directed expression (gold standard); cardiac and pancreatic |
| AAV9 | Terminal N-linked galactose; LamR | Cardiac muscle, skeletal muscle, CNS (crosses BBB in neonates and at high IV dose), liver, lung | Systemic IV for cardiac/skeletal muscle and CNS; intrathecal for spinal cord and DRG |
| AAV-DJ | Engineered chimera (directed evolution from AAV2/8/9) | Broad efficient transduction of mammalian cell lines and primary cells in vitro | In vitro transduction where high efficiency across cell lines is needed; not intended for systemic in vivo use (rapid clearance) |
Selection workflow
- Define the readout. Identify your target tissue/cell type and the experimental window (acute days, weeks, or chronic months).
- Match capsid to tissue. Use the table above as a starting point. For systemic IV, AAV8 (liver), AAV9 (cardiac/skeletal muscle, CNS via BBB), and AAV6 (muscle/lung) are the most common choices. For stereotaxic CNS, AAV2 / AAV5 / AAV9 are first-line. For skeletal muscle, AAV1 / AAV6 / AAV8 / AAV9 all perform well with subtle tissue and species differences.
- Match promoter to expression goal. CMV / CAG / CBA give strong, broadly active expression. Cell-type-specific promoters (CamKIIα, hSyn, GFAP, cTNT, αMHC, TBG, Ttr) restrict expression even when the capsid transduces multiple populations. Capsid-restricted tropism and promoter-restricted expression are independent layers of specificity that can be combined.
- Run a small dose-response. In vitro, test a 10× MOI range with a reporter AAV (e.g., AAV-GFP) of the same serotype to fix optimal MOI before switching to your transgene. In vivo, pilot 2–3 doses with a reporter or matched control vector before scaling.
- Use proper controls. Match capsid serotype, promoter, and dose between test and control vectors. Empty / Null capsid controls (e.g., AAV-Null) match for capsid- and dose-related effects independent of payload; LacZ or GFP-only vectors match for transgene-expression load.
Practical considerations
- Anti-capsid neutralizing antibodies. Pre-existing immunity against AAV2 and several other serotypes is common in human and primate studies and reduces transduction. This is less of a concern in inbred laboratory mouse strains but is reportable in NHP and human-relevant work.
- Route matters as much as capsid. The same capsid can give very different tropism by intravenous vs. intramuscular vs. intrathecal vs. stereotaxic vs. subretinal injection. The "best" capsid for a tissue is route-specific.
- Single-stranded vs. self-complementary (scAAV). Standard recombinant AAV is single-stranded and requires second-strand synthesis after entry, leading to a 1–3 week onset to peak expression. scAAV bypasses this step (faster onset, ~3–7 days) at the cost of half the packaging capacity (~2.4 kb vs. ~4.7 kb).
- ITR backbone. Nearly all recombinant AAVs — across capsid serotypes — use AAV2 ITRs. The capsid identity and the ITR identity are independent design choices.
- Empirical validation is required. Tropism summaries are starting points. Final serotype selection should be validated in a pilot experiment in your specific cell line, animal model, and route of administration.
Selected references on AAV biology and tropism: Wu Z, Asokan A, Samulski RJ. Adeno-associated virus serotypes: vector toolkit for human gene therapy. Mol Ther 2006;14(3):316–327. Zincarelli C, Soltys S, Rengo G, Rabinowitz JE. Analysis of AAV serotypes 1–9 mediated gene expression and tropism in mice after systemic injection. Mol Ther 2008;16(6):1073–1080. Srivastava A. In vivo tissue-tropism of adeno-associated viral vectors. Curr Opin Virol 2016;21:75–80. Pillay S, et al. An essential receptor for adeno-associated virus infection. Nature 2016;530:108–112.
What is this AAV product, briefly?
How should this AAV be stored and handled upon receipt?
What MOI should I start with?
What tropism should I expect from AAV8?
What controls should I include alongside this AAV?
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