Do you have a protocol for concentrating lentivirus?

Yes. In our product manual for the Trans-Lentiviral GIPZ Packaging System, Protocol II. This manual is available for download using the following link: http://www.openbiosystems.com/ProductLiterature.aspx?AliasPath=/Viral%20Packaging/TransLentiviral% 20Packaging%20Syst&CatalogNumber=TLP4614