|Recombinant viral vectors for research & clinical study|
Overexpression (Oex) and knockdown (KD) studies are indispensable approaches for basic and clinical research to determine the role genes play in health and disease. In the last century the discovery of RNAi technology has revolutionized this field of research.
Studies relying on overexpression or knockdown methods are limited by the Principal Investigator's ability to guide either a gene of interest (GOI) or a specific shRNA/siRNA sequence into the desired cell system - summarized in the term ‘gene delivery’.
Many different methods of gene delivery have been developed which can be divided into two main categories, viral and non-viral.
Non-viral methods include physical methods such as microinjection or electroporation and chemical methods, such as lipofection. However, these methods have their limitations since many cell types do not respond to this type of modification. As a major drawback, reproducible results are hard to achieve due to high deviations in transfection rates from experiment to experiment.
Viral gene delivery methods make use of the natural characteristics of viruses and therefore have multiple advantages:
- Viruses are naturally evolved gene vehicles which transfer DNA or RNA into a host’s cell.
- Different types of virus exhibit different host preferences and modes of expression. This tremendous diversity allows for an array of options, catering to any scientific approach and any specific cell system.
- Viruses can target either specific cell types in vitro or can be used in specific animal models for in vivo studies.
- Viral Vectors developed and used by SIRION Biotech are based on RNA and DNA viruses thus being able to process different genomic structures and host ranges.
- In addition, viral vectors developed by SIRION Biotech are replication deficient - which guarantees vector safety.
- By refining vector design and virus production, expression properties are optimized and virus retargeting achieved.
In summary, SIRION Biotech’s expertise offers you the perfect tool for gene delivery in almost any cell system in vitro or in vivo.
We will begin with different viral vectors serving as the main players of the SIRION technology platform:
Adenoviruses are non-enveloped double stranded DNA viruses (36 kb) with an icosahedral structure. In total, more than 50 different human serotypes are known. Most of the adenovirus mediated diseases in humans are mild acute respiratory, gastrointestinal and ocular infections with a high rate of infection.
Recombinant adenoviruses have become a standard tool in gene deliveryin vitrofor gene functionality studies and in vivo for vaccination and gene therapy applications. Several features of Adenovirus biology have made them the vectors of choice for these applications.
- A striking advantage is their highly efficient transduction rate, translating into strong gene knockdown and overexpression potential in nearly all eukaryotic cells - even primary cells, dividing or not.
- Since the viral titers can be tightly controlled, highly reproducible results can be obtained and, consequently standard variations minimized.
- Because DNA transferred by Adenovirus is not integrated into the host-genome the resulting gene expression is transient.
SIRION Biotech`s adenoviral vector platform is based on the genome of the human adenovirus serotype 5 (Ad5).The company’s proprietary AdenoONE BAC recombination system combines both positive and negative selection during virus generation.This restricts the number of recombination events to 1, resulting in a cloning efficiency higher than 98%. Patent pending BAC technology guarantees production times of less than 6 weeks from cloning to final virus preparation and highest product purity.
Lentivirus is a genus of slow viruses of theRetroviridae familycharacterized by a long incubation period. A prominent member of this genus is the “human immunodeficient virus” (HIV). Lentiviruses are enveloped viruses with a single stranded RNA genome. Special features are the viral proteinsReverse TranscriptaseandIntegrasewhich enable the transcription from RNA into DNA followed by stable and random integration into the host genome. These remarkable gene delivery properties combined with cell entry properties can enable transduction of non-dividing cells, and making LV highly attractive as gene modification tools.
SIRION Biotech`s lentiviral vector platform allows for constitutive as well as inducible gene modification. It offers a reliable system for highest gene overexpression or knockdown from vector cloning to a functional tested stable cell pool in less than 6 weeks. SIRION Biotech’s in-house designed multicistronic vectors system enables highest expression control in close to any cell type.
Adeno-associated virus (AAV)
AAV belongs to the genus Dependovirus,which in turn belongs to the family Parvoviridae. AAVs are non-enveloped viruses with a single stranded DNA genome. For replication it is dependent on a helper virus, whereas the first factor that was described as providing successful generation of new AAV particles was the adenovirus, from which the AAV name originated. However, there are exceptions. In in vivo applications, AAVs have shown to cause site-specific integration into the host genome on chromosome 19 leading to replication also in the absence of a helper virus.
Since AAVs are not known to cause disease, they do possess low immunogenicity. This characteristic makes them the perfect tool for in vivo applications. In addition, AAVs enable long term expression of up to 1 year, injection allows tissue specificity due to different surface serotypes, and AAV vectors are BL-1 (S1) compatible.
SIRION Biotech`s AAV vector platform allows for tissue specific viral transduction by using a broad range of different serotypes. Beating advantage is also the fast timeline from cDNA to viral vectors with guaranteed efficacy in less than 3 months.
The webpage of SIRION Biotech serves as a road map to success in developing good viral vectors and cell models. Please refer to the left-hand column for specific information on the various virus products and services for Your own success.