Rational Design-Based Capsid Amino-acid Mutation

Creative Biolabs has an advanced design platform for adeno-associated virus vector (AAV). Our services cover a series of experiments, from the design and development of the vector to the performance test. We can target AAV to specific tissues and organs by changing the amino acid composition of capsid proteins.

Introduction of Targeting AAV Vectors

Recombinant AAV vectors have many attractive features in medical applications, including low immunogenicity, high stability, the persistence of transgene expression, and the possibility of integrating sites without known side effects. In order to achieve efficient and selective transgene production of therapeutic genes in selected cells or tissues, scientists have designed a variety of vector optimization protocols. Although the specificity of the vector itself can be used to achieve specific gene expression in some liver or muscle cells, for most cancers and cardiovascular and cerebrovascular diseases, how to accurately direct genes to the diseased area is still a difficult problem to be solved.

Capsid and genome structure of AAV2. Figure 1. Capsid and genome structure of AAV2.

Capsid Amino-acid Mutation

  • One of the major outcomes of improved AAV transduction was the discovery that protein tyrosine kinases phosphorylate specific residues on the surface of the AAV2 capsid, which causes virions to be ubiquitinated and degrade before reaching the nucleus. Mutation of these residues exposed on the surface of the capsid to those residues that cannot be phosphorylated, such as phenylalanine, can significantly improve the transport of AAV into the cell and greatly improve the efficiency of gene transduction. In addition, wild-type AAV is generally not efficient in its transport to the nucleus in cells, which may be due to the negative regulation of exposed threonine phosphorylation. Mutating it into non-phosphorylated amino acids such as valine, can significantly improve the gene expression ability of AAV2 and AAV6 in clinical applications. However, it is not entirely clear whether the phenomenon is completely mediated by directly affecting nuclear imports.
  • Heparan sulfate proteoglycan (HSPG) was originally recognized as the only classical receptor for AAV2 infection. However, with the development of various protein modification technologies, similar AAV vectors can target specific cells and internalize the transfer of genes without relying on these receptors. On the contrary, these receptors in many cases will interfere with the vector guidance process. Therefore, the HSPG binding motif mutation on AAV vector is used as a scheme to reposition the target of vector infection to avoid targeting the wrong cells in gene therapy vector.

By properly selecting mutations, Creative Biolabs can optimize the targeting of AAV products for customers. We study combinations of different serotypes and various mutant capsid proteins, providing a significant level of versatility in changing the viral transduction profile, which can help us customize AAV applications in different ways. If you are interested in our carrier modification service, you can contact us by email or send us an inquiry to find a complete solution.

For research use only. Not intended for any clinical use.