Efficient Isolation of Novel Human Monoclonal Antibodies with Neutralizing Activity Against HIV-1 from Transgenic Mice Expressing Human Ig Loci

Abstract

Despite considerable interest in the isolation of mAbs with potent neutralization activity against primary HIV-1 isolates, both for identifying useful targets for vaccine development and for the development of therapeutically useful reagents against HIV-1 infection, a relatively limited number of such reagents have been isolated to date. Human mAbs (hu-mAbs) are preferable to rodent mAbs for treatment of humans, but isolation of hu-mAbs from HIV-infected subjects by standard methods of EBV transformation of B cells or phage display of Ig libraries is inefficient and limited by the inability to control or define the original immunogen. An alternative approach for the isolation of hu-mAbs has been provided by the development of transgenic mice that produce fully hu-mAbs. In this report, we show that immunizing the XenoMouse G2 strain with native recombinant gp120 derived from HIVSF162 resulted in robust humoral Ab responses against gp120 and allowed the efficient isolation of hybridomas producing specific hu-mAbs directed against multiple regions and epitopes of gp120. hu-mAbs possessing strong neutralizing activity against the autologous HIVSF162 strain were obtained. The epitopes recognized were located in three previously described neutralization domains, the V2-, V3- and CD4-binding domains, and in a novel neutralization domain, the highly variable C-terminal region of the V1 loop. This is the first report of neutralizing mAbs directed at targets in the V1 region. Furthermore, the V2 and V3 epitopes recognized by neutralizing hu-mAbs were distinct from those of previously described human and rodent mAbs and included an epitope requiring a full length V3 loop peptide for effective presentation. These results further our understanding of neutralization targets for primary, R5 HIV-1 viruses and demonstrate the utility of the XenoMouse system for identifying new and interesting epitopes on HIV-1.

The V1/V2 Domain of gp120 Is a Global Regulator of the Sensitivity of Primary Human Immunodeficiency Virus Type 1 Isolates to Neutralization by Antibodies Commonly Induced upon Infection

“…Similar comparisons were performed for three MAbs directed to the V2 domain: 8.22.2, directed against a linear epitope located at the beginning of the V2 crown (22), and 2158 and 830A, directed against conserved V2-specific disulfide-dependent epitopes similar to that recognized by the previously described human MAb 697D (18). 8.22.2 bound equally well to the two gp120s, but while it weakly neutralized SF162 (ND 50 ϭ 37 g/ml) it did not neutralize the JR-FL pseudotypes at 100 g/ml (Table 1).…”

Characterization of Antibody Responses Elicited by Human Immunodeficiency Virus Type 1 Primary Isolate Trimeric and Monomeric Envelope Glycoproteins in Selected Adjuvants

“…More direct proof of this deduction will require further V1 peptide fine mapping. Strain-restricted, V1-directed antibodies have been reported in Abgenix XenoMouse animals inoculated with SF162 gp120 (23).…”

Isolation and characterization of human anti-acetylcholine receptor monoclonal antibodies from transgenic mice expressing human immunoglobulin loci

“…Several mouse strains harboring human Ig loci have been generated over the last years as an alternative strategy for the generation of human mAb of therapeutic value, and in a number of cases, the efforts have been quite successful [19][20][21][22][23]. However, in a previous study, immunization of mice transgenic for human l, c1, and j germ-line genes (HuMab-Mice) with Torpedo AChR or the fusion protein Trx-Ha1-210 did not result in the isolation of anti-AChR mAb [17].…”