Divergent effects of cell environment on HIV entry inhibitor activity.
OBJECTIVE
Successful HIV vaccine and entry inhibitor development depends on use of assay systems that closely reflect in-vivo activities. Recent reports suggest that the currently most widely used assay format, which relies on the genetically engineered target cell line TZM-bl, can fail to detect certain neutralization activities detected on primary peripheral blood mononuclear cell (PBMC)-based assay systems. In the present study, we investigate the influence the target cell context bears on HIV entry inhibition.


METHODS
In a comprehensive survey, the effect of 11 neutralizing antibodies and inhibitors in blocking entry of 30 envelope pseudotyped virus strains in two types of target cells, PBMC and TZM-bl, was evaluated.


METHODS
Env-pseudotyped HIV infection of PBMC and TZM-bl cells.


RESULTS
We demonstrate here that depending on the type of inhibitor, relative neutralization potencies are shifted to a variable extent and direction on TZM-bl and PBMC cells. In our assay set up, differences in inhibitor activity were solely effected by the target cell environment and amounted up to 2-3 logs lower activity on TZM-bl cells in several cases. Overall, neutralizing antibodies, 2G12, 2F5 and 4E10, were less active in the TZM-bl system, whereas CD4 binding site directed inhibitor activities were detected equally well on both target cells, raising concerns that the TZM-bl assay may overrate the relevance of CD4 binding site specific responses.


CONCLUSIONS
Our data strongly argue that preclinical assessment should not be restricted to a single type of assay, as systematic underestimation or overestimation of activities would be inevitable.
Rusert
Peter
P
Institute of Medical Virology, University of Zurich, University Hospital Zurich, Switzerland.
Mann
Axel
A
Huber
Michael
M
von Wyl
Viktor
V
Gunthard
Huldrych F
HF
Trkola
Alexandra
A
D016915:AIDS Vaccines; D001681:Biological Assay; D023581:HIV Fusion Inhibitors / Q000276:immunology / Q000627:therapeutic use*; D015658:HIV Infections / Q000276:immunology / Q000378:metabolism / Q000517:prevention & control*; D015497:HIV-1; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000378:metabolism; D016032:Randomized Controlled Trials as Topic; D054299:env Gene Products, Human Immunodeficiency Virus / Q000276:immunology / Q000378:metabolism
D016915:AIDS Vaccines; D023581:HIV Fusion Inhibitors; D054299:env Gene Products, Human Immunodeficiency Virus