Virus isolates contain many more infectious virions than can be detected by standard infectious assay measurement
1 . A major problem appears to be the efficient delivery of the virions to the target cell for their subsequent effective uptake by endocytosis
2 or fusion with the plasma membrane. The envelope of HIV-1 contains beside virus-encoded proteins also host cell proteins
3,4 . The HIV Infectivity Enhancement Reagent uses the presence of these host proteins in both the virus envelope and the target cell to tether HIV on the surface of target lymphocytes and macrophages. Pre-treatment of viral isolates with the HIV Infectivity Enhancement Reagent results in an infection of a higher percentage of target cells, increased viral integration events, greatly enhanced kinetics of viral replication, and amplified viral titers and amounts of soluble p24 protein in the cell culture supernatant
5 .