# US 2008/0187997 A1 · Novel lentiviral packaging cells

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2008/0187997 A1
- Document ID: US20080187997A1
- Status: Published application
- Kind: A1
- Application number: 11/983,497
- Filed: 2007-11-09
- Published: 2008-08-07
- Earliest claimed: 1998-05-13
- Assignees: Genetix Pharmaceuticals, Inc.
- Inventors: Philippe Leboulch; Karen Westerman
- Web page: https://patentgrep.com/patent/US20080187997A1

## CPC

- C12N 15/86: Viral vectors
- A61K 48/00: Medicinal preparations containing genetic material which is inserted into cells of the living body to treat genetic diseases; Gene therapy
- C12N 2740/16043: viral genome or elements thereof as genetic vector
- C12N 2740/16052: relating to complementing cells and packaging systems for producing virus or viral particles
- C12N: MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA (microbiological testing media C12Q1/00)
- A61K: PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES (devices or methods specially adapted for bringing pharmaceutical products into particular physical or administering forms A61J3/00; chemical aspects of, or use of materials for deodorisation of air, for disinfection or sterilisation, or for bandages, dressings, absorbent pads or surgical articles A61L; soap compositions C11D)

## Abstract

Novel packaging cell lines which produce recombinant retrovirus, free of detectable helper-virus are disclosed. Also disclosed are methods of making the cell lines and methods of producing recombinant retroviruses from the cell lines. Retroviruses produced by the cell lines include lentiviruses, such as HIV, capable of transferring heterologous DNA to a wide range of non-dividing cells. The packaging cells contain at least three vectors which collectively encode retroviral gag, pol, and env proteins, wherein the gag and pol genes are separated, in part, onto two or more different vectors. This is made possible by fusing Vpr or Vpx to pol proteins separated from gag so that the proteins are targeted to assembling virions. Among other advantages, the packaging cells provide the benefit of increased safety when used in human gene therapy by virtually eliminating the possibility of molecular recombination leading to production of replication-competant helper virus.

## Claims

### Claim 1

A method of producing a packaging cell line capable of producing a recombinant, helper-free retrovirus, comprising transfecting a host cell with:
a first vector comprising a retroviral gag gene;
a second vector comprising a portion of a retroviral pol gene, fused to a Vpr or Vpx gene;
a third vector comprising the remainder of the retroviral pol gene not contained in said second vector, fused to a Vpr or a Vpx gene; and
a fourth vector comprising a viral env gene.

### Claim 2 (depends on 1)

The method of claim 1, wherein transcription of any one of said genes within said vectors is directed by an inducible promoter.

### Claim 3 (depends on 2)

The method of claim 2 further comprising the step of contacting said host cell with an agent which induces said promoter.

### Claim 4 (depends on 1)

The method of claim 1 wherein said retrovirus is a lentivirus.

### Claim 5 (depends on 4)

The method of claim 4, wherein said lentivirus is selected from the group consisting of HIV-1, HIV-2, SIV, FIV and EIV.

### Claim 6 (depends on 1)

The method of claim 1, wherein said retroviral gag gene within said first vector comprises lentiviral matrix, capsid and nucleocapsid proteins.

### Claim 7 (depends on 1)

The method of claim 1, wherein said portion of said pol gene within said second vector encodes a retroviral protease.

### Claim 8 (depends on 7)

The method of claim 7, further comprising transfecting the host cell with retroviral accessory genes.

### Claim 9 (depends on 1)

The method of claim 1, wherein said remainder of said retroviral pol gene within said third vector encodes a retroviral reverse transcriptase and a retroviral integrase.

### Claim 10 (depends on 9)

The method of claim 9, wherein said third vector further comprises a retroviral Vif gene.

### Claim 11 (depends on 1)

The method of claim 1, wherein said viral env gene within said third vector encodes an envelope protein selected from a virus selected from the group consisting of a Type C retrovirus, a lentivirus and Vesicular Stomatitis Virus.

### Claim 12 (depends on 1)

The method of claim 1, wherein any of the first, second, third or fourth vectors further comprise an RNA export element.

### Claim 13 (depends on 12)

The method of claim 12, wherein said RNA export element is the reverse response element (RRE) from human immunodeficiency virus (HIV).

### Claim 14 (depends on 1)

The method of claim 1, wherein any of the first, second, third or fourth vectors further comprise a marker gene.