Recombinant human Fab fragments neutralize human type 1 immunodeficiency virus in vitro.

Abstract

A panel of 20 recombinant Fab fragments reactive with the surface glycoprotein gpl20 of human type 1 immunodeficiency virus (HIV-1) were examined for their ability to neutralize MN and hUB strains of the virus. Neutralization was determined as the ability of the Fab fragments to inhibit infection as measured in both a p24 ELISA and a syncytium-formation assay. One group of closely sequencerelated Fab fragments was found to neutralize virus in both assays with a 50% neutralization titer at -1 ,ug/ml. AnotherFab neutralized in the p24 ELISA but not in the syncytium assay. The other Fab fragments showed weak or no neutralizing ability. The results imply that virion aggregation or crosslinking of gp120 molecules on the virion surface is not an absolute requirement for HIV-1 neutralization. Further, all of the Fab fragments were shown to be competitive with soluble CD4 for binding to gpl20 and yet few neutralized the virus effectively, implying that the mechanism of neutralization in this case may not involve receptor blocking. The observation of a preponderance ofhigh-affminty Fab fragments with poor or no neutralizing ability could have implications for vaccine strategies.

Identification and specificity of broadly neutralizing antibodies against HIV

“…The first HIV bnAbs were isolated by our laboratory using phage display12, 13, 14 and by Hermann Katinger's laboratory using human hybridoma electrofusion 15, 16. These were the bnAbs b12 and 2F5.…”

Llama Antibody Fragments with Cross-Subtype Human Immunodeficiency Virus Type 1 (HIV-1)-Neutralizing Properties and High Affinity for HIV-1 gp120

“…Of these, only a handful have been found to be broadly neutralizing across HIV-1 subtypes (8), and have been the result of HIV-1 infection rather than immunization. Two of these are directed against gp120: MAb b12, which binds to an epitope that overlaps a subset of the CD4-binding site (CD4bs) of gp120 (3,10,11,68,94), and MAb 2G12, which recognizes a carbohydrate motif (9,70,72,80). Two broadly neutralizing MAbs, 4E10 and 2F5, recognize gp41 (9,56,77,96).…”

Increased HIV-1 sensitivity to neutralizing antibodies by mutations in the Env V3-coding region for resistance to CXCR4 antagonists

“…447-52D (Gorny et al, 1992) was purchased from Polymun Scientific Immunbiologische Forschung. b12 (Barbas et al, 1992;Burton et al, 1991Burton et al, , 1994Roben et al, 1994), VRC01 (Wu et al, 2010), 17b (Sullivan et al, 1998;Thali et al, 1993;Trkola et al, 1996;Wyatt et al, 1995, 2G12 Crawford et al, 1999;Etemad-Moghadam et al, 1999;Mascola et al, 1999;Trkola et al, 1996), PG16 (Walker et al, 2009) and 2F5 Purtscher et al, 1994Purtscher et al, , 1996 were obtained from the NIH AIDS Reagent Program, Division of AIDS, NIAID, NIH.…”