Characterizing anti-HIV monoclonal antibodies and immune sera by defining the mechanism of neutralization

Issue title: Humoral immune response against HIV-1

Guest editors: M.K. Gorny

Article type: Research Article

Authors: Crooks, Emma T.^a | Moore, Penny L.^{a; b} | Richman, Douglas^c | Robinson, James^d | Crooks, Jeffrey A.^e | Franti, Michael^f | Schülke, Norbert^g | Binley, James M.^{a; *}

Affiliations: [a] Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121, USA | [b] National Institute for Communicable Diseases, Sandringham, Johannesburg, South Africa | [c] Department of Pathology and Medicine, Veterans Affairs San Diego Healthcare System, and the University of California, San Diego, 9500 Gilman Drive. La Jolla, CA 92093-0679, USA | [d] Department of Pediatrics, Tulane University Medical Center, 1430 Tulane Avenue, New Orleans, LA 70112, USA | [e] Tijuana River National Estuarine Research Reserve, and the Southwest Wetlands Interpretive Association, 301 Caspian Way, Imperial Beach, CA 91932, USA | [f] Progenics Pharmaceuticals, Inc., 777 Old Saw Mill River Road, Tarrytown NY 10591, USA | [g] Millennium Pharmaceuticals, Inc., 35 Landsdowne Street, Cambridge, MA 02139, USA | New York University School of Medicine, c/o Veterans Affairs Medical Center, 423 East, 23rd Street, Room 18124N New York, NY 10010, USA

Correspondence: [*] Corresponding author: J.M. Binley, Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121, USA. Tel.: +1 858 909 5142; Fax: +1 858 455 3804; E-mail: [email protected]

Abstract: Understanding the nature of neutralization may provide information for crafting improvements in HIV vaccines. Using JR-FL as a prototype primary pseudovirus, we first investigated anti-HIV monoclonal antibodies (mAbs) in several neutralization formats designed to elucidate the timing of neutralization. MAb b12 was most effective before receptor binding, 2G12 neutralized effectively even after CD4 binding, and X5 and a V3 loop mAb (LE311) were inactive in a standard format but were induced by sCD4. Consistent with this latter finding, native PAGE indicated that X5 and V3 mAb binding to Envelope trimers was dependent on sCD4 binding. In contrast, 2F5 and 4E10 were active even post-CD4/CCR5 engagement. We next analyzed the neutralization mechanism of a panel of HIV+ donor plasmas of various potencies. All mediated high levels of post-CD4 neutralization that was not associated with activity in the standard format. None, however, neutralized effectively in the post-CD4/CCR5 format, suggesting that 2F5/4E10-like Abs were absent or at low concentrations. Finally, we analyzed a non-neutralizing plasma spiked with mAbs b12, 2G12 or 2F5, which resulted in increases in neutralization titers consistent with the activities of the mAbs. We conclude that these methods, together with other mapping approaches, may provide a better understanding of neutralization that could be useful in vaccine research.

Keywords: HIV, antibody, neutralize, serum, plasma, mapping, vaccine, Envelope, T-20

DOI: 10.3233/HAB-2005-143-407

Journal: Human Antibodies, vol. 14, no. 3-4, pp. 101-113, 2005