Design of a non-glycosylated outer domain-derived HIV-1 gp120 immunogen that binds to CD4 and induces neutralizing antibodies.
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.
Bhattacharyya
Sanchari
S
Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
Rajan
Roshan Elizabeth
RE
Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
Swarupa
Yalla
Y
Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
Rathore
Ujjwal
U
Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560 012, India.
Verma
Anjali
A
Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
Udaykumar
Ranga
R
Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P. O., Bangalore 560 064, India.
Varadarajan
Raghavan
R
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.
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
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