91 results about "Helper virus" patented technology

The present invention relates methods of generating infectious negative-strand virus in host cells by an entirely vector-based system without the aid of a helper virus. In particular, the present invention relates methods of generating infectious recombinant negative-strand RNA viruses intracellularly in the absence of helper virus from expression vectors comprising cDNAs encoding the viral proteins necessary to form ribonucleoprotein complexes (RNPs) and expression vectors comprising cDNA for genomic viral RNA(s) (vRNAs) or the corresponding cRNA(s). The present invention also relates to methods of generating infectious recombinant negative-strand RNA viruses which have mutations in viral genes and / or which express, package and / or present peptides or polypeptides encoded by heterologous nucleic acid sequences. The present invention further relates the use of the recombinant negative-strand RNA viruses or chimeric negative-strand RNA viruses of the invention in vaccine formulations and pharmaceutical compositions.

A method for producing recombinant adeno-associated virus in the absence of contaminating helper virus or wild-type virus involves culturing a mammalian host cell containing an rAd / AAV hybrid virus, an AAV rep sequence and an AAV cap sequence under the control of regulatory sequences directing expression thereof. The rAd / AAV hybrid virus contains a rAAV construct to be packaged into an AAV virion in a backbone containing the adenoviral sequences necessary to express E1a and E1b gene products and to permit replication of the hybrid virus. The method of the invention permits replication of the hybrid virus and production of rAAV virion in this host cell in the absence of a helper virus and obviates a subsequent purification step to purify rAAV from contaminating virus.

The invention provides a composition useful to prepare influenza A viruses, e.g., in the absence of helper virus.

Accessory functions capable of supporting efficient recombinant AAV (rAAV) virion production in a suitable host cell are provided. The accessory functions are in the form of one or more vectors that are capable of being transferred between cells. Methods of producing rAAV virions are also provided. The methods can be practiced to produce commercially significant levels of rAAV particles without also generating significant levels of infectious helper virus or other contaminating by-products.

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 transfering 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.

This invention provides methods and compositions for producing high titer, substantially purified preparations of recombinant adeno-associated virus (AAV) that can be used as vectors for gene delivery. At the onset of vector production, AAV producer cells of this invention typically comprise one or more AAV packaging genes, an AAV vector comprising a heterologous (i.e. non-AAV) transgene of interest, and a helper virus such as an adenovirus. The AAV vector preparations produced are generally replication incompetent but are capable of mediating delivery of a transgene of interest (such as a therapeutic gene) to any of a wide variety of tissues and cells. The AAV vector preparations produced according to this invention are also substantially free of helper virus as well as helper viral and cellular proteins and other contaminants. The invention described herein provides methods of producing rAAV particles by culturing producer cells under conditions, such as temperature and pH, that promote release of virus. Also provided is a quantitative, high-throughput assay useful in the assessment of viral infectivity and replication, as well as in the screening of agent that affect viral infectivity and / or replication.

The invention provides a composition useful to prepare high titer influenza viruses, e.g., in the absence of helper virus, which includes internal genes from an influenza virus vaccine strain or isolate, e.g., one that is safe in humans, for instance, one that does not result in significant disease, and genes from vaccine seed virus isolates which include a HA gene segment with a HA2 sequence encoding a HA2 that confers enhanced growth in cells in culture, such as Vero cells.