The present invention relates to a producer cell which expresses a tagging protein at the cell surface, such that retroviral vectors produced by the cell are tagged with the tagging protein, wherein the tagging protein comprises: i) a binding domain which binds to a capture moiety ii) a spacer; and iii) a membrane targeting domain such that, when incorporated a retroviral vector, the tagging protein facilitates purification of the retroviral vector from cellular supernatant via binding of the tagging protein to the capture moiety. The present invention also relates to a retroviral vector comprising such a producer cell-derived tagging protein.

Human-derived virus-like particles (heVLPs), comprising a membrane comprising a phospholipid bilayer with one or more HERV-derived envelope proteins on the external side; one or more HERV-derived GAG proteins in the heVLP core, and a cargo molecule, e.g., a biomolecule and/or chemical cargo molecule, disposed in the core of the heVLP on the inside of the membrane, wherein the heVLP does not comprise a gag protein, except for gag proteins that are encoded in the human genome or gag proteins that are encoded by a consensus sequence that is derived from gag proteins found in the human genome, and methods of use thereof for delivery of the cargo molecule to cells.

An enveloped viral particle producer or packaging cell, wherein the cell is genetically engineered to decrease expression of MHC-I on the surface of the cell.

A cell for producing retroviral vectors comprising nucleic acid sequences encoding: i) gag-pol; ii) env; iii) the RNA genome of the retroviral vector; and iv) optionally rev, or a functional substitute thereof, wherein at least two nucleic acid sequences are located at the same genetic locus; and wherein the at least two nucleic acid sequences are in reverse and/or alternating orientations.

Described herein are virus-like particles (VLPs) and minimal human-derived virus-like particles (mhVLPs), comprising a membrane comprising a phospholipid bilayer with one or more human-derived envelope glycoproteins (env) on the external side. Optionally, a biomolecule cargo is disposed in the core of the VLP or mhVLP on the inside of the membrane. Preferably, the mhVLPs do not comprise any exogenous virally derived proteins, e.g., proteins from viral gag, pro, or pol, or other viral proteins that reside inside of enveloped particles (unless the cargo comprises the viral protein(s)). In some embodiments, the mhVLPs do not comprise any human endogenous retroviral (HERV) proteins other than the env (hENV), e.g., do not comprise gag, pol, or pro that was exogenously introduced into producer cells. In some embodiments, the VLPs include a targeting domain, either fused at the N or C terminus or internally into the hENV, or as a separate membrane-anchored targeting domain. Also described are methods of use of the VLPs or mhVLPs for delivery of the biomolecule cargo to cells.

The present invention provides methods for producing recombinant viral particles based on the use of exogenous mRNAs to supply various helper factors for assembly of viral particles, purified recombinant viral particles produced using such methods, and methods of using such viral particles.

The present invention relates to a nucleic acid construct comprising: (i) a first nucleic acid sequence which either comprises a retroviral transfer vector or which encodes a retroviral protein; and (ii) a second nucleic acid sequence which encodes a detectable marker which is a cell surface protein comprising an extracellular domain and a membrane targeting domain.

An enveloped viral particle producer or packaging cell, wherein the cell is genetically engineered to decrease expression of MHC-I on the surface of the cell.

The present invention relates to a replication retrovirus vector system comprising thymidine kinase (HSV-TK) gene and cytosine deaminase (CD) gene which make gene transfer to cancer cell tissue for the efficient treatment of cancer. Particularly, the HSV-TK/CD combined self-replicating retrovirus vector system of the present invention characteristically contains both HSV-TK and CD genes; has no worries about losing a therapeutic gene because recombination does not occur in this system during virus infection; and has an excellent stability, and also is able to induce cancer cell death by using the prodrug GCV or 5-FC and can apply a therapeutic gene or a prodrug thereof selectively to such cancer that shows resistance against cancer treatment using either TK or CD, so that this system of the invention can be advantageously used as a pharmaceutical composition for the treatment of cancer.

The present invention provides to a polyethylene glycol-modified feline-derived protein which is obtained by chemically modifying a feline-derived protein with polyethylene glycol. The feline-derived protein is produced by a method comprising any or a combination of extracting the protein from somatic cells of a transgenic bird and/or an egg laid thereby, purifying and activating the same. The transgenic bird has a foreign gene containing a sequence encoding a feline-derived protein.