Adeno Associated Viruses (AAVs)
Small viruses that can carry relatively small payload, but they do not exhibit pathogenicity nor cytotoxicity in the host organism. They can mediate gene transfer to both mitotic and non-mitotic cells, they lack the risk of oncogene activation, since they can exist stably in an episomal state with a low rate of chromosomal integration. AA virions are small (20-25 nm diameter) and have no enveloped, they carry ssDNA and they are defective virus dependent on the presence of a helper virus for replication.
- Require BSL2 safety level lab
- They carry a small payload up to 4.5 Kb
- No pathogenic and replicant-defective.
- AAV dsDNA in host cells is maintained in an “episomal” state (not integrated in the host genome).
- Transgene expression mediate by recombinant AAV vectors can persist for months and up to several years.
- Can be package with different serotypes that confer different infectious spectrum (tropism):
|AAV1||CNS, skeletal muscle, Heart|
|AAV2||CNS, photoreceptor cells||Neurons, general tropism in all brain areas|
|AAV5||CNS, photoreceptor cells, Lung||Astrocytes, hippocampal neurons, Selective retrogade Transport|
|AAV6||Skeletal muscle, Lung||Retrogade transduction|
|AAV7||Skeletal muscle, Liver|
|AAV8||CNS, photoreceptor cells, skeletal muscle, Heart, Liver, Pancreas||High specificity in Auditory Cortex|
|AAV9||CNS, skeletal muscle, Heart, Liver, Lung||Neurons, hippocampus, auditory cortex|
AAV pseudotyping: Define as the mix of a capsid and genome from different viral serotypes. We currently have in stock some plasmids for AAV production purchased from PasmidFactory including pDM and pDG (Wild type AAV2 serotype), and a series of pDP including rep2 (structural protein from AAV2 serotype) and different cap proteins (capsid protein) conferring different tropisms depending which cap proteins are coded.
A) AAV are non-enveloped, icosahedral and small. They package ~4.7 kB, flanked by ITR singled stranded DNA containing two Open Reading Frames encoding for Replication (rep) and capsid (cap) proteins. B) We currently work with recombinant AAV, meaning that AAV ssDNA no longer contains the cap and rep genes but the transgene which will be introduced in the host cells. Therefore, production of these viruses is achieved by co-transfection of the transgene vector and an AAV helper plasmids that contains the necessary genes for the packaging and virus production within the host cells.
Production and ordering of AAVs
Production and packaging available from different pseudotypes. Purchased from PlasmidFactory which holds the license from the German Cancer Research Center, we provide the user with several serotypes to choose from, depending on their needs:
- AAV helper plasmid pDP1 (rep2/cap1)
- AAV helper plasmid pDG (rep2/cap2)
- AAV helper plasmid pDP5 (rep2/cap5)
- AAV helper plasmid pDP6 (rep2/cap6)
- AAV helper plasmid pDP8.ape (rep2/cap8)
- Transfection and supernatant collection
- Virus precipitation.
- Crude Purification by centrifugation, discontinuous Iodixanol gradient and anion exchange using adsorption membrane.
- Buffer exchange and concentration by centrifugation filter devices
- Quality control assay include a physical titter (vg/mL) by RT-qPCR or functional titter (IFU/mL) by FACS when appropriated. The titration is requested by the customer.
Note: AAV vector plasmids are notorious for the instability and frequent deletion of the ITRs when propagated in E. coli. For this reason, it is important to carefully confirm the integrity of every preparation. Even the best plasmid preparations contain significant quantities (5–15%) of DNA containing small deletions in the ITR, which during cloning procedures can be randomly selected and amplified. The integrity of the ITRs is typically monitored by restriction enzyme analysis sufficient to identify small deletions (20 bp). Most commonly this is achieved with digestion with Sma I or Srf I, which cut twice within an unstable portion of the ITR. Because of these stability issues, most investigators utilize a recombination deficient E. coli strain, such as SURE (Agilent Technologies, ref#200152) or NEB stable (NEB, ref#C3040I) for AAV vector plasmid propagation and cloning.
Material provided and price list:
~500 µl in chosen size aliquots, titer ≥1010 vg/mL (viral genomes/mL). Prices include titration by qPCR or FACS:
Physical titration: 8.300 SEK/virus for KI users; 10.000 SEK/virus for external users.
Functional titration (if available): 8.400 SEK/virus for KI users, 10.100 SEK/virus for external users.