title: Design of a non-glycosylated outer domain-derived HIV-1 gp120 immunogen that binds to CD4 and induces neutralizing antibodies.
abstract: The outer domain (OD) of the HIV-1 envelope glycoprotein gp120 is an important target for vaccine design as it contains a number of conserved epitopes, including a large fraction of the CD4 binding site. Attempts to design OD-based immunogens in the past have met with little success. We report the design and characterization of an Escherichia coli-expressed OD-based immunogen (OD(EC)), based on the sequence of the HxBc2 strain. The OD(EC)-designed immunogen lacks the variable loops V1V2 and V3 and incorporates 11 designed mutations at the interface of the inner and the outer domains of gp120. Biophysical studies showed that OD(EC) is folded and protease-resistant, whereas OD(EC) lacking the designed mutations is highly aggregation-prone. In contrast to previously characterized OD constructs, OD(EC) bound CD4 and the broadly neutralizing antibody b12 but not the non-neutralizing antibodies b6 and F105. Upon immunization in rabbits, OD(EC) was highly immunogenic, and the sera showed measurable neutralization for four subtype B and one subtype C virus including two b12-resistant viruses. In contrast, sera from rabbits immunized with gp120 did not neutralize any of the viruses. OD(EC) is the first example of a gp120 fragment-based immunogen that yields significant neutralizing antibodies.
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Sanchari
authors.initials: S
authors.lastname: Bhattacharyya
authors.affiliation: Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
authors.forename: Roshan Elizabeth
authors.initials: RE
authors.lastname: Rajan
authors.affiliation: Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
authors.forename: Yalla
authors.initials: Y
authors.lastname: Swarupa
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: Ujjwal
authors.initials: U
authors.lastname: Rathore
authors.affiliation: Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
authors.forename: Anjali
authors.initials: A
authors.lastname: Verma
authors.affiliation: Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
authors.forename: Ranga
authors.initials: R
authors.lastname: Udaykumar
authors.affiliation: Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India; Chemical Biology Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India. Electronic address: varadar@mbu.iisc.ernet.in.
authors.forename: Raghavan
authors.initials: R
authors.lastname: Varadarajan
mesh_terms: D000818:Animals; D057134:Antibodies, Neutralizing / Q000737:chemistry / Q000276:immunology*; D000914:Antibodies, Viral / Q000737:chemistry / Q000276:immunology*; D001665:Binding Sites / Q000235:genetics / Q000276:immunology; D015704:CD4 Antigens / Q000235:genetics / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D005260:Female; D006031:Glycosylation; D015699:HIV Envelope Protein gp120 / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000494:pharmacology; D015497:HIV-1 / Q000235:genetics / Q000276:immunology*; D006801:Humans; D007114:Immunization; D009154:Mutation; D017510:Protein Folding; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000494:pharmacology
chemical_list: D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D015704:CD4 Antigens; D000939:Epitopes; D015699:HIV Envelope Protein gp120; D011994:Recombinant Proteins; C514793:gp120 protein, Human immunodeficiency virus 1