AVS 50th International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI-ThM

Paper BI-ThM5
Force Spectroscopy Investigation of HIV Envelope Glycoprotein and Dual Antibody Complex using Atomic Force Microscopy

Thursday, November 6, 2003, 9:40 am, Room 318/319

Session: Biosensors
Presenter: Y. Lam, Duke Univ. and Center for Biomolecular and Tissue Eng.
Authors: Y. Lam, Duke Univ. and Center for Biomolecular and Tissue Eng.
W.K. Lee, Duke Univ.
P. Marszalek, Duke Univ. and Center for Biomolecular and Tissue Eng.
M. Alam, Human Vaccine Institute
R. Clark, Duke Univ.
B. Haynes, Human Vaccine Institute
S. Zauscher, Duke Univ. and Center for Biomolecular and Tissue Eng.
Correspondent: Click to Email
Understanding the structure-function relationships of pathogenic molecules is the key to designing sensitive detection mechanisms, as well as effective inhibitory drugs. Atomic force microscopy (AFM) is an optimal tool for investigation of these molecular scale biomechanics, as it provides high temporal and spatial resolution while maintaining an aqueous testing environment. In this study, we use the AFM to examine a well-characterized model system of Human Immunodeficiency Virus-1 (HIV-1) envelope glycoprotein gp120 and several monoclonal antibodies. Antibodies were screened before AFM experiments using surface plasmon resonance (SPR), and chosen for greatest binding affinities. In the AFM experiment, one antibody, a human T-cell CD4 mimic, is immobilized on the surface, and functions to bind gp120 from solution. The second antibody, a human chemokine receptor mimic, is attached to the AFM tip, and only interacts with the bound gp120-CD4 complex. A large majority of trials registered adhesion events, qualitatively signifying the presence of gp120. Quantitative analysis determined antibody-antigen binding strengths on the order of 100 pN, in agreement with binding forces of other molecular recognition systems. Experiments with poly(ethylene glycol) tethers and variable pulling rates provide force profiles revealing details of attachment and detachment mechanisms. Results from this study show that AFM can be used effectively as a detection as well as characterization method to better understand the pathogenic system.