Vectors and viral vectors, and packaging cell lines for propagating same

Abstract

Provided are novel vectors and viral vectors capable of expressing exogenous gene or exogenous nucleic acid sequences in a target cell of interest, such as T cells, bone marrow cells, epithelial cells, liver cells and the like. The nucleic acid components of the vectors may include one or more native promoter / enhancer regions having modified sequence segments, one or more non-native promoter / enhancer or non-native promoter's gene or gene segment, and a native viral vector terminator or processing signal or segment thereof. The viral vectors comprise a virus or viral portion having on the surfaces or envelopes adsorption components, one for a packaging cell line and the other for delivery to a target cell. Other viral vectors provided by this invention have two components on their surfaces or envelopes, one of which is native to the virus and the other being non-native and capable of adsorbing to the target cell while being incapable of adsorbing to a native cell for the viral vector. Packaging cell lines for propagating the vectors and viral vectors are also provided, as are novel processes for propagating any of the disclosed vectors or viral vectors.

Description

FIELD OF THE INVENTION [0001] This invention relates to the field of recombinant nucleic acid technology, and more particularly, to the production of gene expression systems involving novel vectors and viral vectors as well as unique packaging cell lines for propagating such vectors or viral vectors and to the processes for producing them. [0002] All patents, patent applications, patent publications, scientific articles, and the like, cited or identified in this application are hereby incorporated by reference in their entirety in order to describe more fully the state of the art to which the present invention pertains. BACKGROUND OF THE INVENTION [0003] Virus and nucleic acid vectors provide a means to deliver nucleic acid sequences to cells, and they are widely used in gene therapy applications. Critical to effective gene therapy is the ability to establish efficient expression of an Exogenous Nucleic Acid(s) in the target cell. Expression of exogenous nucleic acid in target cells...

AI Technical Summary

Benefits of technology

[0012] The present invention provides novel vectors and viral vectors for use in systems for delivering and expressing desired genes and gene sequences. One such novel vector is shown to be capable of expressing an exogenous gene or exogenous nucleic acid sequences in a target cell of interest. The vector comprises a viral vector, a viral vector nucleic acid, or a nucleic acid construct that comprises a viral vector nucleic acid sequence. The vector comprises the following nucleic acid component or components: i) one or more native promoter / enhancer regions in which at least one sequence segment has been modified, (ii) one or more non-native promoter / enhancers or a non-native promoter's gene or gene segment, and (iii) a native viral vector terminator or a processing signal or segment thereof, or both.

Problems solved by technology

Although each particular family of virus may possess elements that confer specific advantages for development into a virus vector, each virus family also contains inherent features that limit its use as a viable means of human gene transfer.

Nevertheless, several intrinsic features of retroviruses have hindered their use as virus vectors, and efforts to modify them to produce safe and efficient vectors have led to low yields of virus vector or to the inefficient expression of the exogenous gene in the target cell.

In the absence of 3′ RNA processing, such as polyadenylation, newly transcribed mRNA is highly unstable and, therefore, subject to immediate degradation.

Several problems arise from the use of this method.

This extra sequence can not only sterically hinder both the intermolecular and intramolecular transfer of templates during reverse transcription of the viral vector RNA, but can also decrease the packaging efficiency and the size of the exogenous nucleic acid sequence which can be inserted into the virus vector due to the size restriction of the RNA which can be packaged (Whitcomb, J. M. and Hughes, S. H. 11992] Ann. Rev. Cell Biol.

In cases where reverse transcription does occur, the exogenous polyadenylation signal is lost during the process of reverse transcription and it cannot be used for polyadenylation of mRNA transcribed from an internal gene which does not contain its own polyadenylation signal.

Virus vectors such as retroviruses that can randomly integrate into a cell genome have the potential to disrupt the structure and function of cell genes.

Whereas certain viruses possess useful properties for gene transfer, their use is limited by the requirement for a helper virus or by an inability to provide for stable transfer of Exogenous Nucleic Acid to a target cell.

While such specific integration makes AAV an attractive candidate for use as a virus vector, existing AAV vectors cannot integrate at specific sites in a target cell genome.

Other features that hinder the use of AAV vectors for gene therapy are the size restriction of the internal gene, the difficulty in growing virus in large amounts and the risk of helper-virus free contamination, all of which stem from the intrinsic mechanism of AAV replication.

While native virus vectors may possess a natural affinity for target cells, such viruses pose a greater hazard since they possess a greater potential for propagation in target cells.

Virus vectors produced in this way, however, normally lack any components either as part of the envelope or as part of the capsid that can provide tropism for human cells.

While non-viral nucleic acid complexes can provide significant advantages for gene delivery, these advantages have not or cannot be realized by the use of non-viral nucleic acid complexes that rely on non-specific binding components.

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