Name: Forfatter i søkelyset: Effektiv adeno-assosiert virusisolering for prekliniske applikasjoner
Uploaded: 2024-02-09T14:30:00
Description: Watch this Scientific Journal Video about Author Spotlight: Efficient Adeno-Associated Virus Isolation for Pre-Clinical Applications at JoVE.com

Sammensetningen av løsningene og bufferne som brukes i denne protokollen er angitt i tabell 1.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody><tr><td>Løsning</td>
			<td colspan="2">Komposisjon</td>
		</tr><tr><td rowspan="4">AAV lysis buffer</td>
			<td colspan="2">1,2 ml 5 M NaCl-løsning</td>
		</tr><tr><td colspan="2">2 ml Tris-HCl pH 8,5 oppløsning</td>
		</tr><tr><td colspan="2">80 uL med 1 M MgCl2-løsning</t...

AAV-isolasjon ved dobbel jodixanoltetthetsgradientsentrifugering

<ol>
	<li>Strauss, K. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Onasemnogene+abeparvovec+for+presymptomatic+infants+with+three+copies+of+SMN2+at+risk+for+spinal+muscular+atrophy:+the+Phase+III+SPR1NT+trial.">Onasemnogene abeparvovec for presymptomatic infants with three copies of SMN2 at risk for spinal muscular atrophy: the Phase III SPR1NT trial.</a> Nat Med. 28 (7), 1390-1397 (2022).</li><li>Fuller-Carter, P. I., Basiri, H., Harvey, A. R., Carvalho, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Focused+update+on+AAV-based+gene+therapy+clinical+trials+for+inherited+retinal+degeneration.">Focused update on AAV-based gene therapy clinical trials for inherited retinal degeneration.</a> BioDrugs. 34 (6), 763-781 (2020).</li><li>George, L. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multiyear+factor+VIII+expression+after+AAV+gene+transfer+for+hemophilia+A.">Multiyear factor VIII expression after AAV gene transfer for hemophilia A.</a> N Engl J Med. 385 (21), 1961-1973 (2021).</li><li>Naso, M. F., Tomkowicz, B., Perry, W. L., Strohl, W. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adeno-Associated+Virus+(AAV)+as+a+vector+for+gene+therapy.">Adeno-Associated Virus (AAV) as a vector for gene therapy.</a> Biodrugs. 31 (4), 317-334 (2017).</li><li>Atchison, R. W., Casto, B. C., Hammon, W. M. c. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+tools+for+production+and+purification+of+recombinant+adenoassociated+virus+vectors.">Novel tools for production and purification of recombinant adenoassociated virus vectors.</a> Hum Gene Ther. 9 (18), 2745-2760 (1998).</li><li>Zolotukhin, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recombinant+adeno-associated+virus+purification+using+novel+methods+improves+infectious+titer+and+yield.">Recombinant adeno-associated virus purification using novel methods improves infectious titer and yield.</a> Gene Ther. 6 (6), 973-985 (1999).</li><li>Clark, K. R., Liu, X., Mcgrath, J. P., Johnson, P. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Highly+purified+recombinant+adeno-associated+virus+vectors+are+biologically+active+and+free+of+detectable+helper+and+wild-type+viruses.">Highly purified recombinant adeno-associated virus vectors are biologically active and free of detectable helper and wild-type viruses.</a> Hum Gene Ther. 10 (6), 1031-1039 (1999).</li><li>Debelak, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cation-exchange+high-performance+liquid+chromatography+of+recombinant+adeno-associated+virus+type+2.">Cation-exchange high-performance liquid chromatography of recombinant adeno-associated virus type 2.</a> J Chromatogr B Biomed Sci App. 740 (2), 195-202 (2000).</li><li>Burova, E., Ioffe, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chromatographic+purification+of+recombinant+adenoviral+and+adeno-associated+viral+vectors:+methods+and+implications.">Chromatographic purification of recombinant adenoviral and adeno-associated viral vectors: methods and implications.</a> Gene Ther. 12 (1), S5-S17 (2005).</li><li>Adams, B., Bak, H., Tustian, A. 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S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chitosan-based+vector/DNA+complexes+for+gene+delivery:+Biophysical+characteristics+and+transfection+ability.">Chitosan-based vector/DNA complexes for gene delivery: Biophysical characteristics and transfection ability.</a> Pharm Res. 15 (9), 1332-1339 (1998).</li><li>Vandenberghe, L. H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+serotype-dependent+release+of+functional+vector+into+the+culture+medium+during+adeno-associated+virus+manufacturing.">Efficient serotype-dependent release of functional vector into the culture medium during adeno-associated virus manufacturing.</a> Hum Gene Ther. 21 (10), 1251-1257 (2010).</li><li>Summerford, C., Samulski, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Membrane-associated+heparan+sulfate+proteoglycan+is+a+receptor+for+adeno-associated+virus+type+2+virions.">Membrane-associated heparan sulfate proteoglycan is a receptor for adeno-associated virus type 2 virions.</a> J Virol. 72 (2), 1438-1445 (1998).</li><li>Wright, J. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+factors+that+contribute+to+recombinant+AAV2+particle+aggregation+and+methods+to+prevent+its+occurrence+during+vector+purification+and+formulation.">Identification of factors that contribute to recombinant AAV2 particle aggregation and methods to prevent its occurrence during vector purification and formulation.</a> Mol Ther. 12 (1), 171-178 (2005).</li><li>Gruntman, A. M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stability+and+compatibility+of+recombinant+adeno-associated+virus+under+conditions+commonly+encountered+in+human+gene+therapy+trials.">Stability and compatibility of recombinant adeno-associated virus under conditions commonly encountered in human gene therapy trials.</a> Hum Gene Ther Methods. 26 (2), 71-76 (2015).</li><li>Srivastava, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rationale+and+strategies+for+the+development+of+safe+and+effective+optimized+AAV+vectors+for+human+gene+therapy.">Rationale and strategies for the development of safe and effective optimized AAV vectors for human gene therapy.</a> Mol Ther Nucleic Acids. 32, 949-959 (2023).</li><li>Mullard, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FDA+approves+first+gene+therapy+for+Duchenne+muscular+dystrophy,+despite+internal+objections.">FDA approves first gene therapy for Duchenne muscular dystrophy, despite internal objections.</a> Nat Rev Drug Discov. 22 (8), 610-610 (2023).</li><li>Center for Biologics Evaluation and Research. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Approved+Cellular+and+Gene+Therapy+Products.">Approved Cellular and Gene Therapy Products.</a> US Food Drug Adm. , (2023).</li><li>Kang, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AAV+vectors+applied+to+the+treatment+of+CNS+disorders:+Clinical+status+and+challenges.">AAV vectors applied to the treatment of CNS disorders: Clinical status and challenges.</a> J Control Release Off J Control Release Soc. 355, 458-473 (2023).</li><li>De Wolf, D., Singh, K., Chuah, M. 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Den doble renseprotokollen for jodixanolgradient er den universelle metoden fordi den kan brukes på alle AAV-muterte varianter, uavhengig av reseptorspesifisitet. Tidlige metoder for AAV-rensing baserte seg på partikkeltetthet og inkluderte isopycnic sentrifugering i CsCl og kontinuerlig sukrose tetthet gradient sentrifugering19. Senere ble serotypespesifikke tilnærminger utviklet, som benyttet monoklonale antistoffer bundet til Sepharose-kolonnene20. En ny tetthetsbaser...

Rekombinante adenoassosierte virale (rAAV) vektorer er mye brukte verktøy for behandling av genetiske sykdommer, inkludert spinal muskelatrofi, retinal dystrofi og hemofili A 1,2,3. rAAV-vektorer er konstruert for å mangle virusgener tilstede i villtype AAV4, et lite, ikke-konvolutt icosahedral virus med et lineært enkeltstrenget 4,7 kb DNA-genom. AAV ble først oppdaget på 1960-tallet som forurensning av adenoviruspreparater5. Til tross for den lille kapsidstørrelsen, som begrenser størrelsen på transgenet som kan pakkes til maksimalt 4,9 kb unntatt ITR6, er AAV nyttig for transgenfødsel fordi det er ikke-patogent hos mennesker, tillater ekspresjon av transgen i mange delende og ikke-delende celletyper, og har begrensede immunogene effekter7.
Som medlemmer av slekten dependoparvovirus er produksjonen av rAAVs avhengig av uttrykket av hjelpergener tilstede i adenovirus eller herpes simplex-virus8. Det er utviklet flere strategier for å produsere rAAV, men produksjon i HEK293-celler transformert med adenovirale E1A/E1B-hjelpergener er den mest etablerte metoden som brukes i dag9. Den generelle tilnærmingen til rAAV-produksjon begynner med transfeksjon av HEK293-celler med tre plasmider som inneholder transgenet i henholdsvis inverterte terminale repetisjoner (ITR), AAV-rep - og cap-gener og ytterligere adenovirale hjelpergener. Syttito timer etter transfeksjon høstes og behandles celler for å rense rAAV som inneholder transgenet.
I utviklingen av nye rAAV-vektorer for terapeutiske formål er et hovedmål å produsere vektorer med økt transduksjonseffektivitet. En økning i transduksjonseffektiviteten til målceller vil bety en reduksjon i den nødvendige kliniske dosen av rAAV, og dermed redusere sannsynligheten for uønskede immunogene effekter fra antistoffmediert nøytralisering til akutt toksisitet10,11. For å forbedre transduksjonseffektiviteten til rAAV-vektorer, kan endringer gjøres i det pakkede genomet eller til kapsiden. Levedyktige metoder for å justere transduksjonseffektiviteten via pakket genomdesign inkluderer inkorporering av sterke og vevsspesifikke promotorer, gjennomtenkt utvalg av mRNA-prosesseringselementer og kodingssekvensoptimalisering for å forbedre oversettelseseffektiviteten12. Endringer i kapsidet er gjort med sikte på å øke tropismen for målhumane celletyper. Arbeidet med å utvikle nye rAAV-transgene leveringsvektorkapsider er generelt preget av fokus på enten rasjonell design av AAV-kapsider med spesifikke mutasjoner rettet mot spesifikke cellereseptorer eller rettet evolusjon for å identifisere kapsider med tropisme for spesifikke celletyper fra kombinatoriske kapsidbiblioteker med høy kompleksitet uten å målrette mot en spesifikk reseptor (selv om noen grupper kombinerer disse tilnærmingene)13, 14,15. I den regisserte evolusjonstilnærmingen konstrueres kombinatoriske kapsidbiblioteker ved hjelp av en bestemt serotyperyggrad med muterte variable regioner på kapsidets eksteriør16. Kombinatoriske kapsidbiblioteker er ofte konstruert fra AAV-serotyper som ikke stammer fra mennesker, noe som reduserer risikoen for allerede eksisterende immunitet ved klinisk bruk10. Derfor er rensemetoder som kan brukes på enhver serotype ideelle for å eliminere behovet for serotypespesifikk optimalisering for de mindre brukte serotypene som tjener som ryggrad for disse bibliotekene.
Iodixanol tetthet gradient sentrifugering benyttes til å rense høye titere av rAAV med høy smittsomhet17. I denne protokollen produseres rAAV i suspensjonscellekultur for å redusere arbeidsmengden som trengs for å produsere store titere av AAV. Et sentrifugeringstrinn er også inkludert for å klarcellelysat for å redusere tilstedeværelsen av forurensende proteiner og redusere risikoen for virusutfelling. Denne protokollen er en kostnadseffektiv metode for å produsere preparater av rAAV med høy renhet egnet for preklinisk bruk.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>5810 R benchtop centrifuge</td>
			<td>Eppendorf</td>
			<td>22625501</td>
			<td></td>
		</tr>
		<tr>
			<td>8-channel peristaltic pump&#160;</td>
			<td>Watson-Marlow</td>
			<td>020.3708.00A</td>
			<td></td>
		</tr>
		<tr>
			<td>Automated cell counter&#160;</td>
			<td>NanoEntek</td>
			<td>EVE-MC</td>
			<td></td>
		</tr>
		<tr>
			<td>Avanti J-E high-speed centrifuge</td>
			<td>Beckman Coulter</td>
			<td>369001</td>
			<td></td>
		</tr>
		<tr>
			<td>Benzonase</td>
			<td>Thermo Scientific</td>
			<td>88701</td>
			<td></td>
		</tr>
		<tr>
			<td>Biological safety cabinet</td>
			<td>Labconco</td>
			<td>322491101</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 incubator with shaker&#160;</td>
			<td></td>
			<td></td>
			<td>Set at 8% CO2 and 37 &#176;C</td>
		</tr>
		<tr>
			<td>Conical centrifuge tubes</td>
			<td>Thermo Scientific</td>
			<td>339652</td>
			<td>50 mL</td>
		</tr>
		<tr>
			<td>Conical centrifuge tubes</td>
			<td>Thermo Scientific</td>
			<td>339650</td>
			<td>15 mL</td>
		</tr>
		<tr>
			<td>Disposable micro-pipets</td>
			<td>Fisherbrand</td>
			<td>21-164-2G</td>
			<td>Capillaries</td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s phosphate buffered saline without CaCl2 and MgCl2&#160; (DPBS) (10x)</td>
			<td>Sigma-Aldrich</td>
			<td>D1408</td>
			<td></td>
		</tr>
		<tr>
			<td>ECLIPSE Ts2R-FL inverted microscope</td>
			<td>Nikon</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Expi293 Expression Medium</td>
			<td>Gibco</td>
			<td>A1435101</td>
			<td></td>
		</tr>
		<tr>
			<td>Expi293F cells</td>
			<td>Gibco</td>
			<td>A14527</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter tips</td>
			<td>USA Scientific</td>
			<td>1126-7810</td>
			<td>1000 &#181;L</td>
		</tr>
		<tr>
			<td>Filter tips</td>
			<td>USA Scientific</td>
			<td>1120-8810</td>
			<td>200 &#181;L</td>
		</tr>
		<tr>
			<td>Filter tips</td>
			<td>USA Scientific</td>
			<td>1120-1810</td>
			<td>20 &#181;L</td>
		</tr>
		<tr>
			<td>Filter tips</td>
			<td>USA Scientific</td>
			<td>1121-3810</td>
			<td>10 &#181;L</td>
		</tr>
		<tr>
			<td>Hypodermic needles</td>
			<td>Tyco Healthcare</td>
			<td>820112</td>
			<td>20 GA x 1-1/2 A</td>
		</tr>
		<tr>
			<td>Ice bucket with lid</td>
			<td>VWR</td>
			<td>10146-184</td>
			<td></td>
		</tr>
		<tr>
			<td>JS-5.3 rotor</td>
			<td>Beckman Coulter</td>
			<td>368690</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnesium chloride solution (1 M)</td>
			<td>Millipore Sigma</td>
			<td>M1028-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Metal stand and clamp&#160;</td>
			<td>Fisherbrand</td>
			<td>05-769-6Q</td>
			<td></td>
		</tr>
		<tr>
			<td>Microcentrifuge tubes</td>
			<td>Eppendorf</td>
			<td>22600028</td>
			<td>1.5 mL</td>
		</tr>
		<tr>
			<td>Needle nose pliers</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Optima XE-90 ultracentrifuge</td>
			<td>Beckman Coulter</td>
			<td>A94471</td>
			<td></td>
		</tr>
		<tr>
			<td>Opti-MEM I Reduced-Serum Medium</td>
			<td>Gibco</td>
			<td>31985062</td>
			<td></td>
		</tr>
		<tr>
			<td>OptiPrep density gradient media (iodixanol)</td>
			<td>Serumwerk</td>
			<td>AXS-1114542</td>
			<td>60% iodixanol solution</td>
		</tr>
		<tr>
			<td>P1000 Pipet</td>
			<td>Gilson</td>
			<td>F144059M</td>
			<td></td>
		</tr>
		<tr>
			<td>P2 Pipet</td>
			<td>Gilson</td>
			<td>F144054M</td>
			<td></td>
		</tr>
		<tr>
			<td>P20 Pipet</td>
			<td>Gilson</td>
			<td>F144056M</td>
			<td></td>
		</tr>
		<tr>
			<td>P200 Pipet</td>
			<td>Gilson</td>
			<td>F144058M</td>
			<td></td>
		</tr>
		<tr>
			<td>Phenol red&#160;solution</td>
			<td>Sigma-Aldrich</td>
			<td>P0290</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline (PBS)</td>
			<td>Sigma-Aldrich</td>
			<td>P4474</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipet-Aid XP pipette controller</td>
			<td>Drummond Scientific</td>
			<td>4-000-101</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmid pCapsid</td>
			<td>De novo or Addgene, etc.&#160;</td>
			<td>N/A</td>
			<td>We used pACGrh74.&#160;</td>
		</tr>
		<tr>
			<td>Plasmid pHelper</td>
			<td>Addgene</td>
			<td>112867</td>
			<td></td>
		</tr>
		<tr>
			<td>Plasmid pTransgene</td>
			<td>De novo or Addgene, etc.&#160;</td>
			<td>N/A</td>
			<td>We used pdsAAV-GFP.</td>
		</tr>
		<tr>
			<td>Pluronic F-68 polyol solution (10%)</td>
			<td>Mp Biomedicals</td>
			<td>92750049</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylene glycol 8000</td>
			<td>Research Products International</td>
			<td>P48080-500.0</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyethylenimine HCl Max (PEI-Max)</td>
			<td>Polysciences</td>
			<td>NC1038561</td>
			<td>Dilute in water to 40 &#956;M</td>
		</tr>
		<tr>
			<td>Polypropylene centrifuge tubes, sterile</td>
			<td>Corning</td>
			<td>431123</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>Polypropylene centrifuge tubes, sterile</td>
			<td>Corning</td>
			<td>430776</td>
			<td>250 mL</td>
		</tr>
		<tr>
			<td>Polypropylene Optiseal tubes</td>
			<td>Beckman Coulter</td>
			<td>361625</td>
			<td></td>
		</tr>
		<tr>
			<td>Serological pipettes</td>
			<td>Alkali Scientific</td>
			<td>SP250-B</td>
			<td>50 mL</td>
		</tr>
		<tr>
			<td>Serological pipettes</td>
			<td>Alkali Scientific</td>
			<td>SP225-B</td>
			<td>25 mL</td>
		</tr>
		<tr>
			<td>Serological pipettes</td>
			<td>Alkali Scientific</td>
			<td>SP210-B</td>
			<td>10 mL</td>
		</tr>
		<tr>
			<td>Serological pipettes</td>
			<td>Alkali Scientific</td>
			<td>SP205-B</td>
			<td>5 mL</td>
		</tr>
		<tr>
			<td>Shaker flasks</td>
			<td>Fisherbrand</td>
			<td>PBV1000</td>
			<td>1 L</td>
		</tr>
		<tr>
			<td>Shaker flasks</td>
			<td>Fisherbrand</td>
			<td>PBV50-0</td>
			<td>500 mL</td>
		</tr>
		<tr>
			<td>Shaker flasks</td>
			<td>Fisherbrand</td>
			<td>PBV250</td>
			<td>250 mL</td>
		</tr>
		<tr>
			<td>Shaker flasks</td>
			<td>Fisherbrand</td>
			<td>PBV12-5</td>
			<td>125 mL</td>
		</tr>
		<tr>
			<td>Sodium chloride solution (5 M)</td>
			<td>Fisher Scientific</td>
			<td>NC1752640</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterile syringes</td>
			<td>Fisherbrand</td>
			<td>14-955-458</td>
			<td>5 mL</td>
		</tr>
		<tr>
			<td>Syringe filter</td>
			<td>Millipore</td>
			<td>SLGV013SL</td>
			<td>0.22 micron</td>
		</tr>
		<tr>
			<td>Tris-HCl pH 8.5 (1 M)</td>
			<td>Kd Medical</td>
			<td>RGE3363</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypan blue solution</td>
			<td>Gibco</td>
			<td>15250061</td>
			<td></td>
		</tr>
		<tr>
			<td>Tube rack assembly</td>
			<td>Beckman Coulter</td>
			<td>361646</td>
			<td></td>
		</tr>
		<tr>
			<td>Tube spacers (x4)</td>
			<td>Beckman Coulter</td>
			<td>361669</td>
			<td></td>
		</tr>
		<tr>
			<td>Tubing for peristaltic pump</td>
			<td>Fisher Scientific</td>
			<td>14190516</td>
			<td></td>
		</tr>
		<tr>
			<td>Type 70 Ti fixed-angle titanium rotor</td>
			<td>Beckman Coulter</td>
			<td>337922</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra low temperature freezer</td>
			<td></td>
			<td></td>
			<td>Set at -70 &#176;C</td>
		</tr>
		<tr>
			<td>Vivaspin 20 centrifugal concentrator</td>
			<td>Sartorius</td>
			<td>VS2041</td>
			<td></td>
		</tr>
		<tr>
			<td>Water bath&#160;</td>
			<td></td>
			<td></td>
			<td>Set at 37 &#176;C</td>
		</tr>
	</tbody>
</table>

suspension culture production and purification of adeno-associated virus by iodixanol density gradient centrifugation for in vivo applications

Denne protokollen beskriver rekombinant adenoassosiert virus (rAAV) produksjon og rensing ved iodixanoltetthetsgradientsentrifugering, en serotype-agnostisk metode for rensing av AAV først beskrevet i 1999. rAAV-vektorer er mye brukt i genterapiapplikasjoner for å levere transgener til forskjellige humane celletyper. I dette arbeidet produseres det rekombinante viruset ved transfeksjon av Expi293-celler i suspensjonskultur med plasmider som koder for transgenet, vektorkapsid og adenovirale hjelpergener. Sentrifugering av iodiksanolgradient renser fulle AAV-partikler basert på partikkeltetthet. I tillegg er tre trinn inkludert i denne nå allestedsnærværende metodikken for å øke det totale virusutbyttet, redusere risikoen for nedbør på grunn av forurensende proteiner, og videre konsentrere det endelige virusproduktet, henholdsvis: utfelling av virale partikler fra cellemedier ved bruk av en løsning av polyetylenglykol (PEG) og natriumklorid, innføring av en andre runde av sentrifugering av jodixanoltetthetsgradient, og bufferutveksling via et sentrifugalfilter. Ved hjelp av denne metoden er det mulig å konsekvent oppnå titere i området 1012 virale partikler/ml eksepsjonell renhet for in vivo bruk.

Recombinant adeno-associated viral (rAAV) vectors are widely used tools for the treatment of genetic diseases, including spinal muscular atrophy, retinal dystrophy, and hemophilia A1,2,3. rAAV vectors are engineered to lack viral genes present in wild-type AAV4, a small, non-envelope icosahedral virus with a linear single-stranded 4.7 kb DNA genome. AAV was first discovered in the 1960s as a contaminant of adenovirus preparations5. Despite its small capsid size, which limits the size of the transgene that can be packaged to a maximum of 4.9 kb excluding ITRs6, AAV is useful for transgene delivery because it is non-pathogenic in humans, allows expression of transgene in many dividing and nondividing cell types, and has limited immunogenic effects7.
As members of the genus dependoparvovirus, the production of rAAVs relies on the expression of helper genes present in adenovirus or herpes simplex virus8. Several strategies to produce rAAV have been developed, but production in HEK293 cells transformed with the adenoviral E1A/E1B helper genes is the most established method used today9. The general approach of rAAV production begins with the transfection of HEK293 cells with three plasmids containing the transgene within inverted terminal repeats (ITRs), AAV rep and cap genes, and additional adenoviral helper genes, respectively. Seventy-two hours after transfection, cells are harvested and processed to purify rAAV containing the transgene.
In the development of new rAAV vectors for therapeutic purposes, a major goal is producing vectors with increased transduction efficiency. An increase in the transduction efficiency of target cells would mean a decrease in the necessary clinical dose of rAAV, thus decreasing the likelihood of adverse immunogenic effects ranging from antibody-mediated neutralization to acute toxicities10,11. To improve the transduction efficacy of rAAV vectors, alterations can be made to the packaged genome or to the capsid. Viable methods to tune transduction efficacy via packaged genome design include the incorporation of strong and tissue-specific promoters, thoughtful selection of mRNA processing elements, and coding sequence optimization to improve translation efficiency12. Alterations to the capsid are made with the goal of increasing tropism for target human cell types. Efforts towards developing new rAAV transgene delivery vector capsids are generally characterized by a focus on either rational design of AAV capsids with specific mutations targeting specific cell receptors or directed evolution to identify capsids with tropism for specific cell types from high-complexity combinatorial capsid libraries without targeting one specific receptor (although some groups combine these approaches)13,14,15. In the directed evolution approach, combinatorial capsid libraries are constructed using a particular serotype backbone with mutated variable regions on the capsid exterior16. Combinatorial capsid libraries are often constructed from AAV serotypes not originating in humans, decreasing the risk of preexisting immunity during clinical use10. Therefore, purification methods that can be applied to any serotype are ideal to eliminate the need for serotype-specific optimization for the less commonly used serotypes serving as backbones for these libraries.
Iodixanol density gradient centrifugation is utilized to purify high titers of rAAV with high infectivity17. In this protocol, rAAV is produced in suspension cell culture to decrease the amount of labor needed to produce large titers of AAV. A centrifugation step is also included to clear cell lysate to reduce the presence of contaminating proteins and decrease the risk of virus precipitation. This protocol is a cost-effective method to produce preparations of high-purity rAAV suitable for pre-clinical use.

Forfatter i søkelyset: Effektiv adeno-assosiert virusisolering for prekliniske applikasjoner

Suspensjonskultur Produksjon og rensing av adenoassosiert virus ved iodiksanoltetthet gradient sentrifugering for in vivo applikasjoner

We use a directed evolution approach to identify adeno-associated viral capits with higher tropism for target human cell types. Through this research, we aim to produce recombinant adeno-associated viral vectors with improved target cell transduction and clinical relevance within the field of gene therapy. Our group recently de-targeted several AAV serotypes from the liver by incorporating capsid residues original to an AAV serotype that naturally possesses decreased liver tropism.If successfully expanded to additional serotypes, this provides the groundwork to decrease necessary RAAV clinical dose by peripheral injection and reduce adverse patient outcomes. The IODIXanol purification method while being cost effective is difficult to scale up. Additionally, in downstream applications, the directed evolution approach is performed with animal models or in vitro.So capsid isolated by directed evolution may not transduce in vivo targets in humans to the same extent as in preclinical models. This protocol is affordable and accessible for smaller labs. Additionally, this method yields high purity, recombinant adeno-associated virus that can be used for downstream preclinical in vivo applications.

Denne metoden kan brukes til å oppnå titere på minst 1012 virale partikler per ml. En titer kan fås (figur 3) ved qPCR ved bruk av ITR-primerne gitt i tilleggstabell 1, ved ddPCR eller ved en hvilken som helst annen titreringmetode. Suboptimale titere kan skyldes bruk av et cap-gen som koder for et kapsid med dårlig emballasjeeffektivitet.
En annen mulig kilde til suboptimale resultater er den dårlige transduksjonseffekti...

Watch this Scientific Journal Video about Author Spotlight: Efficient Adeno-Associated Virus Isolation for Pre-Clinical Applications at JoVE.com

Adenoassosiert virus produseres i suspensjonscellekultur og renses ved dobbel iodixanoltetthetsgradientsentrifugering. Trinn er inkludert for å øke det totale virusutbyttet, redusere risikoen for virusutfelling og ytterligere konsentrere det endelige virusproduktet. Forventede endelige titre når 1012 virale partikler/ml og er egnet for preklinisk in vivo bruk.

This protocol describes recombinant adeno-associated virus (rAAV) production and purification by iodixanol density gradient centrifugation, a ...

Vi bruker en rettet evolusjonstilnærming for å identifisere adeno-assosierte virale capits med høyere tropisme for målhumane celletyper. Gjennom denne forskningen tar vi sikte på å produsere rekombinante adenoassosierte virale vektorer med forbedret målcelletransduksjon og klinisk relevans innen genterapi. Vår gruppe målrettet nylig flere AAV-serotyper fra leveren ved å inkorporere kapsidrester opprinnelig fra en AAV-serotype som naturlig har nedsatt levertropisme.Hvis det utvides til flere serotyper, gir dette grunnlaget for å redusere nødvendig RAAV klinisk dose ved perifer injeksjon og redusere uønskede pasientutfall. Den IODIXanol rensing metoden samtidig være kostnadseffektiv er vanskelig å skalere opp. I tillegg, i nedstrømsapplikasjoner, utføres den rettede evolusjonstilnærmingen med dyremodeller eller in vitro.Så kapsid isolert ved rettet evolusjon kan ikke transducere in vivo-mål hos mennesker i samme grad som i prekliniske modeller. Denne protokollen er rimelig og tilgjengelig for mindre laboratorier. I tillegg gir denne metoden høy renhet, rekombinant adenoassosiert virus som kan brukes til nedstrøms prekliniske in vivo-applikasjoner.

suspension-culture-production-purification-adeno-associated-virus

Research

JoVE Journal

Medicine

Suspension Culture Production and Purification of Adeno-Associated Virus by Iodixanol Density Gradient Centrifugation for In Vivo Applications

This protocol describes recombinant adeno-associated virus (rAAV) production and purification by iodixanol density gradient centrifugation, a serotype-agnostic method of purifying AAV first described in 1999. rAAV vectors are widely used in gene therapy applications to deliver transgenes to various human cell types. In this work, the recombinant virus is produced by transfection of Expi293 cells in suspension culture with plasmids encoding the transgene, vector capsid, and adenoviral helper genes. Iodixanol density gradient centrifugation purifies full AAV particles based on particle density. Additionally, three steps are included in this now-ubiquitous methodology in order to increase total virus yield, decrease the risk of precipitation due to contaminating proteins, and further concentrate the final virus product, respectively: precipitation of viral particles from cell media using a solution of polyethylene glycol (PEG) and sodium chloride, the introduction of a second round of iodixanol density gradient centrifugation, and buffer exchange via a centrifugal filter. Using this method, it is possible to consistently achieve titers in the range of 1012 viral particles/mL of exceptional purity for in vivo use.

Adeno-associated virus is produced in suspension cell culture and purified by double iodixanol density gradient centrifugation. Steps are included to increase total virus yield, decrease the risk of virus precipitation, and further concentrate the final virus product. Expected final titers reach 1012 viral particles/mL and are suitable for pre-clinical in vivo use.