Abstract: Provided herein are methods for producing a replication defective retrovirus, which comprises transfecting a producer cell with (1) a retroviral genome; (2) a nucleotide sequence coding for retroviral gag and pol proteins that is codon-optimized for expression in the producer cell; and (3) nucleotide sequences encoding other essential viral packaging components not encoded by the nucleotide sequence of (1).

Abstract: Retroviral vector production systems for producing lentivirus-based vector particles which are capable of infecting and transducing non-dividing target cells, wherein one or more of the auxiliary genes such as vpr, vif, tat, and nef in the case of HIV-1 are absent from the system. The systems and resulting retrovirus vector particles have improved safety over existing systems and vectors.

Abstract: A viral vector production system is provided which system comprises:

Abstract: Retroviral vector production systems for producing lentivirus-based vector particles which are capable of infecting and transducing non-dividing target cells, wherein one or more of the auxiliary genes such as vpr, vif, tat, and nef in the case of HIV-1 are absent from the system. The systems and resulting retrovirus vector particles have improved safety over existing systems and vectors.

Abstract: A retroviral vector derived from a non-primate lentivirus genome comprising a deleted gag gene wherein the deletion in gag removes one or more nucleotides downstream of nucleotide 350 of the gag coding sequence.

Abstract: A viral vector production system is provided which system comprises: (i) a viral genome comprising at least one first nucleotide sequence encoding a gene product capable of binding to and effecting the cleavage, directly or indirectly, of a second nucleotide sequence, or transcription product thereof, encoding a viral polypeptide required for the assembly of viral particles; (ii) a third nucleotide sequence encoding said viral polypeptide required for the assembly of the viral genome into viral particles, which third nucleotide sequence has a different nucleotide sequence to the second nucleotide sequence such that said third nucleotide sequence, or transcription product thereof, is resistant to cleavage directed by said gene product. The viral vector production system may be used to produce viral particles for use in treating or preventing viral infection.

Abstract: A selection system suitable for use in vivo is provided, the system comprising: I) a plurality of first nucleotide sequences encoding a gene product capable of binding to and effecting the cleavage, directly or indirectly, of a nucleotide sequence, or a transcription product thereof; wherein a region of the first nucleotide sequence required for binding to the nucleotide sequence is heterogeneous within the plurality of first nucleotide sequences; and ii) a second nucleotide sequence comprising: (a) a coding region encoding a detectable marker operably linked to sequences required for mRNA stability and/or translation; and (b) a third nucleotide sequence positioned between the coding region and at least one of the sequences required for mRNA stability and/or translation; wherein (a) and (b) are operably linked to a regulatory sequence capable of directing expression of (a) and (b) as a contiguous RNA molecule in a host cell; and wherein the first nucleotide sequence encoding a gene product is capable of bindi

Abstract: Retroviral vector production systems for producing lentivirus-based vector particles which are capable of infecting and transducing non-dividing target cells, wherein one or more of the auxiliary genes such as vpr, vif, tat, and nef in the case of HIV-1 are absent from the system. The systems and resulting retrovirus vector particles have improved safety over existing systems and vectors.

Abstract: Retroviral vector production systems for producing lentivirus-based vector particles which are capable of infecting and transducing non-dividing target cells, wherein one or more of the auxiliary genes such as vpr, vif, tat, and nef in the case of HIV-1 are absent from the system. The systems and resulting retrovirus vector particles have improved safety over existing systems and vectors.

Abstract: A retroviral vector derived from a non-primate lentivirus genome comprising a deleted gag gene wherein the deletion in gag removes one or more nucleotides downstream of nucleotide 350 of the gag coding sequence.