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Time Frames for Neutralization during the Human Immunodeficiency Virus Type 1 Entry Phase, as Monitored in Synchronously Infected Cell Cultures
Journal article   Open access   Peer reviewed

Time Frames for Neutralization during the Human Immunodeficiency Virus Type 1 Entry Phase, as Monitored in Synchronously Infected Cell Cultures

Hillel Haim, Israel Steiner and Amos Panet
Journal of virology, Vol.81(7), pp.3525-3534
04/2007
DOI: 10.1128/JVI.02293-06
PMCID: PMC1866073
PMID: 17251303
url
https://doi.org/10.1128/JVI.02293-06View
Published (Version of record) Open Access

Abstract

Characterization of the neutralizing interaction between antibody and virus is hindered by the nonsynchronized progression of infection in cell cultures. Discrete steps of the viral entry sequence cannot be discerned, and thus, the mode of antibody-mediated interference with virus infectivity remains undefined. Here, we magnetically synchronize the motion and cell attachment of human immunodeficiency virus type 1 (HIV-1) to monitor the progression of neutralization, both in solution and following virus attachment to the cell. By simultaneous transfer of all viral particles from reaction solution with antibody to the cell-bound state, the precise rate of neutralization of cell-free virus could be determined for each antibody. HIV-1 neutralization by both monoclonal and polyclonal antibody preparations followed distinct pseudo-first-order kinetics. For all antibodies, cell types, and HIV-1 strains examined, postattachment interference served a major role in the neutralizing effect. To monitor the progression of postattachment interference, we synchronized the entry process at initiation and measured the escape of cell-bound virus from antibody. We found that different antibodies neutralized the virus over different time frames during the entry phase. Virus was observed to progress through a sequence of shifting sensitivities to different antibodies during entry, suggested here to correlate with the exposure time of the target epitope on receptor-activated viral envelope proteins. Thus, by monitoring the progression of HIV-1 entry under synchronized conditions, we identify a new and significant determinant of antibody neutralization capacity, namely, the time frames for neutralization during the course of the viral entry phase.
Virus-Cell Interactions

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