Recombinant Borna Virus Vector for CNS Gene Therapy

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Solution Overview

Problem

Current viral vectors for gene therapy, such as those using retroviruses, lentiviruses, adenoviruses, and adeno-associated viruses, face challenges including pathogenicity, narrow host range, low gene introduction efficiency, and poor stability due to immune response and mutation, particularly when targeting central nervous system cells.

Innovation Solution

A recombinant Borna disease virus vector with a disrupted G gene and an inserted G gene from avian Bornavirus, combined with ribozymes and a promoter sequence, is used to enhance replicative efficiency and specificity for central nervous system cells, allowing efficient foreign gene introduction without chromosomal integration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional viral vectors (retrovirus, lentivirus, adenovirus) are used for gene introduction, then gene introduction capability is achieved, but pathogenicity occurs due to viral gene integration into host chromosome

Engineering Contradiction:

Improvegene introduction capabilityVSAvoidpathogenicity

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes the harmful G gene from the Borna disease virus genome to create a safe viral vector. By deleting the G gene which is responsible for pathogenicity while retaining other essential viral genes (N, P, M, L) and introducing a foreign gene, the vector maintains gene introduction capability without causing pathogenic effects through chromosomal integration

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention converts the normally harmful G gene into a beneficial component by replacing it with a G gene from avian Bornavirus. This replacement G gene provides necessary viral functions while the deleted original G gene eliminates pathogenicity, thus converting a harmful element into a beneficial one for safe gene therapy

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Ease of manufacture

If DNA virus vectors are used, then gene introduction is achieved, but stability and persistency are poor due to immune response and mutation

Engineering Contradiction:

Improvegene introduction efficiencyVSAvoidviral vector stability

Core Design Contradiction:

Ease of manufactureVSStability of the object's composition

Solution Approach 1:

The invention changes the fundamental parameter of the viral genome from DNA to RNA (single-stranded negative-sense RNA). This parameter change confers stability and persistency because RNA viruses like Borna disease virus can maintain their genome without integrating into host chromosomes, avoiding immune detection and mutation issues associated with DNA viral vectors

Inventive Principle:

Principle #35Parameter changes

3Ease of manufacture

If foreign gene is inserted into conventional viral vectors, then gene introduction is achieved, but gene introduction efficiency varies with insertion site

Engineering Contradiction:

Improvegene introduction capabilityVSAvoidgene introduction efficiency consistency

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The invention creates a universal insertion system by providing multiple suitable insertion sites within the Borna disease virus genome (between N-P genes, between P-M genes, or between M-L genes). Each site can accommodate foreign genes of various sizes and types, ensuring consistent high-efficiency gene introduction regardless of which site is used, thus achieving universality and multi-functionality

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of manufacture

If conventional viral vectors are used, then some gene introduction capability is achieved, but host range is narrow and limited to particular organisms

Engineering Contradiction:

Improvegene introduction capabilityVSAvoidhost range

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The invention segments the viral genome into essential functional components (N, P, M, L genes) and optional components (G gene). By maintaining the essential genes that provide broad host range capability while making the G gene optional or replaceable, the vector achieves wide host range adaptability across different mammalian species including humans, mice, rats, and primates

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS11421247B2Borna viral vector and use thereof

Publication Date: 2022.08.23 KYOTO UNIV

AI summary

Disclosed is a viral vector comprising (a) a cDNA of a recombinant viral RNA having a sequence of a Borna disease viral genome comprising a disrupted G gene of the Borna disease viral genome and an inserted G gene of an avian bornaviral genome, wherein the cDNA of the recombinant viral RNA has at least an N gene, an X gene, a P gene and an L gene of the Borna disease viral genome in the same order as in the Borna disease viral genome and has an inserted foreign gene; (b) DNAs encoding ribozymes; and (c) a promoter sequence, wherein (b) the DNAs encoding ribozymes are located upstream and downstream of (a) the cDNA of the recombinant viral RNA, and (a) the cDNA of the recombinant viral RNA and (b) the DNAs encoding ribozymes are located downstream of (c) the promoter sequence. The present invention can be used as a gene introduction technique that does not affect a host chromosome and can be suitable for the application in various fields, such as the treatment and prevention of brain and neurological diseases, visualization techniques of nerve cells in the field of neuroscience, etc.