Design, display and immunogenicity of HIV1 gp120 fragment immunogens on virus-like particles

• Published in: Vaccine Vol. 36; no. 42; pp. 6345 - 6353
• Main Authors: Purwar, Mansi, Pokorski, Jonathan K., Singh, Pranveer, Bhattacharyya, Sanchari, Arendt, Heather, DeStefano, Joanne, La Branche, Celia C., Montefiori, David C., Finn, M.G., Varadarajan, Raghavan
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 08.10.2018; Elsevier Limited
• Subjects: Animals; Antibodies; Antibodies, Neutralizing - immunology; Antibody response; Antigens; Binding Sites; CD4 antigen; CD4 Antigens - metabolism; Circular dichroism; Competition; Design; Dichroism; Displays; Disulfide bonds; E coli; Epitopes; Escherichia coli - metabolism; Fragmentation; Glycoprotein gp120; Glycoproteins; HIV; HIV Envelope Protein gp120 - immunology; HIV Envelope Protein gp120 - metabolism; Human immunodeficiency virus; Immune focusing; Immune response; Immune system; Immunization; Immunogenicity; Immunoglobulins; Ligands; Mutation; Nanoparticles; Nanoparticles - chemistry; Neutralizing antibodies; Polypeptides; Protein Stability; Proteins; Rabbits; Surface Plasmon Resonance; Vaccine; Vaccines; Virus-like particles; Viruses; PBS; RU; PBSB; Neutralizing antibodies; Protein stability; Vaccine; CD4bs; MODIP; Env; CP; Immune focusing; Nanoparticles; VLPs; SPR; OD; PBST; RLU; Cys; SMCC; ELISA
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2018.07.032

•gp120 fragments with enhanced stability, affinity to CD4bs antibody b12 were designed.•Stabilized fragments were displayed on Qβ VLP’s and used in rabbit immunizations.•The most stable fragment elicited cross clade Tier 1 and weak Tier 2 neutralization.•Priming with the fragments resulted in an epitope focused response to the CD4bs. The broadly neutralizing antibody against HIV-1, b12, binds to the CD4 binding site (CD4bs) on the outer domain (OD) of the gp120 subunit of HIV-1 Env. We have previously reported the design of an E. coli expressed fragment of HIV-1 gp120, b122a, containing about 70% of the b12 epitope with the idea of focusing the immune response to this structure. Since the b122a structure was found to be only partially folded, as assessed by circular dichroism and protease resistance, we attempted to stabilize it by the introduction of additional disulfide bonds. One such mutant, b122a1-b showed increased stability and bound b12 with 30-fold greater affinity as compared to b122a. Various b122a and OD fragment proteins were displayed on the surface of Qβ virus-like particles. Sera raised against these particles in six-month long rabbit immunization studies could neutralize Tier1 viruses across different subtypes with the best results observed with b122a1-b displayed particles. Significantly higher amounts of antibodies directed towards the CD4bs were also elicited by particles displaying b122a1-b. This study highlights the ability of fragment immunogens to focus the antibody response to the conserved CD4bs of HIV-1.