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Assessment of Immunologically Relevant Dynamic Tertiary Structural Features of the HIV-1 V3 Loop Crown R2 Sequence by ab initio Folding
10:50

Assessment of Immunologically Relevant Dynamic Tertiary Structural Features of the HIV-1 V3 Loop Crown R2 Sequence by ab initio Folding

Published on: September 15, 2010

HIV-2 neutralization by intact V3-specific Fab fragments

Samer Sourial1, Charlotta Nilsson

  • 1Department of Microbiology, Tumor and Cellbiology, Karolinska Institute, Stockholm, Sweden. samer.sourial@astrazeneca.com

Virology Journal
|August 19, 2008
PubMed

The V3 region of both HIV-1 gp120 and HIV-2 gp125 surface glycoprotein has been described as a target for neutralizing antibodies. In this study a conformation-sensitive (3C4) and a linear site-specific (7C8) anti-HIV-2 V3 monoclonal antibody (mAb) were characterized. The neutralization capacity of the purified mAbs and their respective papain-generated Fab fragments was analyzed. The Fabs were further characterized by sequence analysis. Our results demonstrate that neither purified mAbs were capable of neutralizing HIV-2, while intact Fab fragments from both mAbs blocked in vitro infection of HIV-2 isolates. Moreover, the conformation sensitive 3C4 Fab neutralized both subtype A and B HIV-2 isolates and SIVsm. Sequence analysis of the hypervariable regions of 3C4 Fab and 7C8 Fab revealed that the third CDR of the heavy chain (CDRH3) of the antibodies was not as long as many of the previously characterized neutralizing antibodies. Our findings suggest that whole 7C8 and 3C4 mAbs are sterically hindered from neutralizing HIV-2, whereas the smaller size of Fab fragments enables access to the V3 region on the virion surface.

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