High-titer, wild-type free recombinant adeno-associated virus vector production using intron-containing helper plasmids. 2000

L Cao, and Y Liu, and M J During, and W Xiao
CNS Gene Therapy Center, Department of Neurosurgery, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.

Recombinant adeno-associated virus (rAAV) is capable of directing long-term, high-level transgene expression without destructive cell-mediated immune responses. However, traditional packaging methods for rAAV vectors are generally inefficient and contaminated with replication-competent AAV (rcAAV) particles. Although wild-type AAV is not associated with any known human diseases, contaminating rcAAV particles may affect rAAV gene expression and are an uncontrolled variable in many AAV gene transfer studies. In the current study, a novel strategy was designed to both optimize AAV rep gene expression and increase vector yield, as well as simultaneously to diminish the potential of generating rcAAV particles from the helper plasmid. The strategy is based on the insertion of an additional intron in the AAV genome. In the AAV infectious clone, the intron insertion had no effects on the properties of Rep proteins expressed. Normal levels of both Rep and Cap proteins were expressed, and the replication of the AAV genome was not impaired. However, the generation of infectious rcAAV particles using intronized AAV helper was greatly diminished, which was due to the oversized AAV genome caused by the insertion of the artificial introns. Moreover, the rAAV packaging was significantly improved with the appropriate choice of intron and insertion position. The intron is another element that can regulate the rep and cap gene expression from the helper plasmid. This study provides for a novel AAV packaging system which is highly versatile and efficient. It can not only be combined with other AAV packaging systems, including rep-containing cell lines and herpes simplex virus hybrid packaging methods, but also be used in other vector systems as well.

UI MeSH Term Description Entries
D007438 Introns Sequences of DNA in the genes that are located between the EXONS. They are transcribed along with the exons but are removed from the primary gene transcript by RNA SPLICING to leave mature RNA. Some introns code for separate genes. Intervening Sequences,Sequences, Intervening,Intervening Sequence,Intron,Sequence, Intervening
D010957 Plasmids Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS. Episomes,Episome,Plasmid
D011995 Recombination, Genetic Production of new arrangements of DNA by various mechanisms such as assortment and segregation, CROSSING OVER; GENE CONVERSION; GENETIC TRANSFORMATION; GENETIC CONJUGATION; GENETIC TRANSDUCTION; or mixed infection of viruses. Genetic Recombination,Recombination,Genetic Recombinations,Recombinations,Recombinations, Genetic
D005822 Genetic Vectors DNA molecules capable of autonomous replication within a host cell and into which other DNA sequences can be inserted and thus amplified. Many are derived from PLASMIDS; BACTERIOPHAGES; or VIRUSES. They are used for transporting foreign genes into recipient cells. Genetic vectors possess a functional replicator site and contain GENETIC MARKERS to facilitate their selective recognition. Cloning Vectors,Shuttle Vectors,Vectors, Genetic,Cloning Vector,Genetic Vector,Shuttle Vector,Vector, Cloning,Vector, Genetic,Vector, Shuttle,Vectors, Cloning,Vectors, Shuttle
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000229 Dependovirus A genus of the family PARVOVIRIDAE, subfamily PARVOVIRINAE, which are dependent on a coinfection with helper adenoviruses or herpesviruses for their efficient replication. The type species is Adeno-associated virus 2. Adeno-Associated Viruses,Dependoparvovirus,Adeno-Associated Virus,Virus, Adeno-Associated,Viruses, Adeno-Associated,Adeno Associated Virus,Adeno Associated Viruses,Dependoparvoviruses,Dependoviruses,Virus, Adeno Associated,Viruses, Adeno Associated
D014162 Transfection The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES. Transfections

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