Patent Evaluation: Methods for the Improved Production of Recombinant Retroviruses

Summary

Novelty: Methods for the improved production of recombinant retroviruses are disclosed.

Biology: The generation of packaging cell lines, which facilitate the production of recombinant retroviruses at high titre, is described. The cells are selected, as they express high levels of all the required packaging proteins. Non-murine packaging cell lines, which produce titres of virus at least ten-fold higher than standard murine packaging cell lines, while avoiding the production of endogenously activated retroviruses and the packaging of defective murine retroviral sequences, are provided. Techniques are also provided for the generation of packaging cell lines which contain alternative envelope proteins and allow the production of xenotropic or polytrophic recombinant retroviruses. The production of retrovirses which can be targeted to specific cell types by utilizing a packaging cell line which expresses a hybrid env gene comprising the cytoplasmic segment of a retroviral env gene, fused to a receptor-binding domain specific for the targeted cell, is also described.