According to statistics, at least 24 A**gene ** drugs have been approved for IND in China, of which 3 are in the clinical stage. However, there are still some challenges to this **, such as transient expression, immune response, and safety issues. A**Gene is an emerging technology developed in response to these problems, and its emergence is expected to redefine the future of Gene**.
Through AI-assisted and efficient screening, Cyagen can provideInnovative A** purified virus for use in vitro cells or in vivo in animals, with a variety of serotypes to choose from, and fast virus delivery in as little as 2 weeks。At the same time, based on the professional gene CRO service platform, Cyagen can also provideIn vivo injection, downstream effectiveness evaluationand other comprehensive services.
Commonly used vectors for genes
Genes can generally be divided into in vivo genes and ex vivo genes. Among them, in vivo** is mainly to deliver non-viral or viral vectors with ** genes, such as the commonly used adeno-associated virus (a**), directly into the patient;In vitro, the gene is introduced into the patient's cells in vitro (often lentivirus LV is used), amplified and then infused back into the patient. Compared with in vitro**, the in vivo** method has higher requirements for gene delivery tools, i.e., vectors
The choice of gene delivery tools is a key part of the gene, and the final effect of the drug in the human body depends largely on the stable and efficient delivery system. At present, the commonly used vectors for genes include viral vectors and non-viral vectorsDue to their wide range of hosts and long duration of action, viral vectors are more and more widely used in gene research, and can perform operations such as overexpression, interference, knockout and endogenous activation of coding genes or non-coding genes.
At present, there are four commonly used viral vectors: A**, AD, RV and LVAmong them, a** is currently the most widely used delivery vector for in vivo genes due to its good tissue specificity, low immunogenicity and high safety.
Table 1 Comparison of virus characteristics of commonly used tools and comparison of various indicators of viral vectors.
About adeno-associated virus (a**).
Clinical trials of gene ** mainly use recombinant adeno-associated virus vectors (RA**).It is modified from the non-pathogenic wild-type A**, and only two reverse terminal repeats (ITRs) are retained to replace the original genome with the gene of interest, maximizing the capacity of carrying the gene of interest and reducing its immunogenicity and cytotoxicity.
The purified a** viral vector can be used to infect cells, that is, the a**capsid protein binds to the cell surface-specific receptor, triggering a** to enter the cell through receptor-mediated endocytosis, and enters the nucleus with the assistance of organelles such as endosomes, and the capsid protein is degraded. It then uncoats and releases its single-stranded genome, which is then converted into a double-stranded DNA template for transcription and translationSo as to achieve the expression of the gene of interest.
Different serotypes of A** have different tissue targeting specificities, and the process of A** entering cells depends on the recognition of a**capsid protein by the glycosylation receptor on the cell surface, so the A**capsid protein determines the specificity of its tissue targeting. By modifying and mutating the A** capsid protein sequence, new tissue-prone A** serotypes can be generatedAt present, 13 natural serum subtypes (A**1-13) and nearly 200 variants of A** have been discovered, and the commonly used ones are A**2, A**5, A**8 and A**9.
Table 2 Tissue targeting specificity of different serotypes A**.