title: Characterization of a macaque recombinant monoclonal antibody that binds to a CD4-induced epitope and neutralizes simian immunodeficiency virus.
abstract: A potent neutralizing Fab fragment from a long-term survivor of simian immunodeficiency virus (SIVsm) infection was used to construct a recombinant macaque immunoglobulin G1kappa (IgG1kappa) molecule, designated IgG1-201. A Chinese hamster ovary cell line expressing IgG1-201 was derived by stable transfection and optimized for antibody secretion by methotrexate selection and dihydrofolate reductase gene amplification. IgG1-201 effectively neutralized the homologous, molecularly cloned SIVsmH4 virus but had no activity against the heterologous SIVmac251/BK28 virus. The previously characterized, neutralization-resistant SIVsmE543-3 virus was also not neutralized by IgG1-201. Binding to SIVsmH4 gp120 was enhanced in the presence of recombinant soluble CD4, suggesting that IgG1-201 bound a CD4-induced epitope. IgG1-201 immunoprecipitated the SIVsmH4 but not the SIVsmE543-3 envelope despite a close relationship between these two clones. Immunoprecipitation of a panel of SIVsmH4/SIVsmE543-3 chimeric viruses tentatively assigned the neutralization epitope to the third constant domain, immediately C terminal to the V3 loop. These findings suggest the presence of at least one CD4-induced neutralization epitope on SIV, as is the case with human immunodeficiency virus type 1.
authors.affiliation: Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA.
authors.forename: J
authors.initials: J
authors.lastname: Glamann
authors.forename: V M
authors.initials: VM
authors.lastname: Hirsch
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D000914:Antibodies, Viral / Q000276:immunology / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D016466:CHO Cells; D019556:COS Cells; D006224:Cricetinae; D000939:Epitopes / Q000276:immunology / Q000378:metabolism*; D005803:Genes, Immunoglobulin; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008252:Macaca fascicularis; D008253:Macaca mulatta; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D011233:Precipitin Tests; D011994:Recombinant Proteins / Q000276:immunology / Q000378:metabolism; D015302:Simian Immunodeficiency Virus / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000914:Antibodies, Viral; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D011994:Recombinant Proteins