Scaleable chromatographic purification process for recombinant adeno-associated virus (rAAV)

Addition of six-His-tagged peptide to the C terminus of adeno-associated virus VP3 does not affect viral tropism or production

Production of large quantities of recombinant adeno-associated virus (AAV) is difficult and not cost-effective. To overcome this problem, we have explored the feasibility of creating a recombinant AAV encoding a 6xHis tag on the VP3 capsid protein. We generated a plasmid vector containing a six-His (6xHis)-tagged AAV VP3. A second plasmid vector was generated that contained the full-length AAV capsid capable of producing VP1 and VP2, but not VP3 due to a mutation at position 2809 that encodes the start codon for VP3. These plasmids, necessary for production of AAV, were transfected into 293 cells to generate a 6xHis-tagged VP3mutant recombinant AAV. The 6xHis-tagged VP3 did not affect the formation of AAV virus, and the physical properties of the 6xHis-modified AAV were equivalent to those of wild-type particles. The 6xHis-tagged AAV did not affect the production titer of recombinant AAV and could be used to purify the recombinant AAV using an Ni-nitrilotriacetic acid column. Addition of the 6xHis tag did not alter the viral tropism compared to wild-type AAV. These observations demonstrate the feasibility of producing high-titer AAV containing a 6xHis-tagged AAV VP3 capsid protein and to utilize the 6xHis-tagged VP3 capsid to achieve high-affinity purification of this recombinant AAV.

A versatile and scalable two-step ion-exchange chromatography process for the purification of recombinant adeno-associated virus serotypes-2 and -5

Here we describe the development of a two-step chromatography process based on the use of ion-exchange resins for the purification of recombinant adeno-associated virus (rAAV) serotypes-2 and-5. In vitro and in vivo results demonstrate that this method, which does not require any prepurification step of the cell lysate, can be applied to obtain highly pure rAAV2 and rAAV5 stocks. As such,this procedure can be easily transferred in vector cores and also scaled up, allowing the direct comparison of these two, and potentially other, AAV serotypes in large animal models.

Scalable purification of adeno-associated virus type 2, 4, or 5 using ion-exchange chromatography

The availability of high-titer, high-purity, adeno-associated virus type 2 (AAV2) stocks has dramatically increased our understanding of this virus and its utility as a gene transfer vector. Current methods of purification take advantage of the stable interaction of AAV2 with heparin sulfate. This affinity chromatography, however, is not useful for purifying AAV4 and AAV5, because these serotypes lack heparin-binding activity. We have developed simple ion exchange high-performance liquid chromatography (HPLC) method for purifying different AAV serotypes that does not rely on the affinity of the viruses for heparin. The protocol is fast, efficient, and yields highly infectious material. Analysis of the highly purified virus indicated that more than 90% of the particles contained genomes and were more active than virus purified by cesium chloride (CsCl) gradient purification. This procedure is scalable and can easily be streamlined for large-scale production of recombinant adeno-associated virus (rAAV), regardless of the serotype. Ultimately, the new purification method will further the characterization of rAAV of different serotypes as vectors for gene therapy applications.