title: Optimized Infectivity of the Cell-Free Single-Cycle Human Immunodeficiency Viruses Type 1 (HIV-1) and Its Restriction by Host Cells.
abstract: The infectivity of retroviruses such as HIV-1 in plasma or cultured media is less than 0.1% in general, the mechanisms of which are not yet fully understood. One possible explanation among others is the potential presence of large numbers of defective virions in a virus pool, which limits the apparent infectivity of HIV virions. To test this hypothesis, we have varied the culture conditions used to generate single-cycle HIV-1 virions. Among these culture variables, virion harvest time, media change after transfection, and envelope plasmid input can all improve HIV-1 infectivity by reducing the number of defective virions. A harvest time of 18-24 hours post transfection as opposed to 48 hours, and a media change six hours post transfection both improve viral infectivity. An optimal quantity of envelope plasmid input during transfection was also found. Collectively, these conditions increased the infectivity of HIV-1 virions by sevenfold compared to normally reported values in TZM-bl indicator cell lines. These conditions also increased the infectivity of HIV-1 in CD4(+) T cells, suggesting that these conditions work by increasing the intrinsic infectivity of a virus pool. Nevertheless, these improvements on virion infectivity were marginal compared to the impact of host cells on HIV infection, which can decrease the apparent infectivity by 19-fold even for the most optimized viruses. These results suggest that the infectivity of HIV-1 virions can be optimized by reducing the number of defective virions; however, viral-cell interactions may pose a major barrier for HIV-1 infectivity.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Michigan, Ann Arbor, Michigan, United States of America.
authors.forename: Jin H
authors.initials: JH
authors.lastname: Kim
authors.forename: Hanna
authors.initials: H
authors.lastname: Song
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Austin
authors.forename: Wei
authors.initials: W
authors.lastname: Cheng
mesh_terms: D002474:Cell-Free System; D015497:HIV-1 / Q000472:pathogenicity*; D006801:Humans; D010957:Plasmids; D014162:Transfection; D014771:Virion / Q000472:pathogenicity; D014774:Virulence