Chimeric HIV-1 envelope glycoproteins with potent intrinsic granulocyte-macrophage colony-stimulating factor (GM-CSF) activity

• Published in: PloS one Vol. 8; no. 4; p. e60126
• Main Authors: Isik, Gözde, van Montfort, Thijs, Boot, Maikel, Cobos Jiménez, Viviana, Kootstra, Neeltje A, Sanders, Rogier W
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 02.04.2013; Public Library of Science (PLoS)
• Subjects: Antibodies; Antibodies, Neutralizing; Antigens; Biology; CD4 Antigens - metabolism; Cell Line; Cell proliferation; Chimeras; Cleavage; Colonies; Colony-stimulating factor; Comparative analysis; env Gene Products, Human Immunodeficiency Virus - genetics; env Gene Products, Human Immunodeficiency Virus - immunology; env Gene Products, Human Immunodeficiency Virus - metabolism; Epitopes - immunology; Gene Order; Genetic aspects; Glycoproteins; Glycosylation; Granulocyte-macrophage colony stimulating factor; Granulocyte-Macrophage Colony-Stimulating Factor - genetics; Granulocyte-Macrophage Colony-Stimulating Factor - immunology; Granulocyte-Macrophage Colony-Stimulating Factor - metabolism; Granulocytes; HIV; HIV Antibodies - immunology; HIV Antibodies - metabolism; HIV-1 - genetics; HIV-1 - immunology; Human immunodeficiency virus; Humans; Humoral immunity; Immunity; Immunogenicity; Immunoglobulin G - immunology; Immunoglobulin G - metabolism; Immunoglobulins; Immunology; Infections; Laboratories; Lymphocytes B; Lymphocytes T; Macrophages; Medicine; Monocytes; Monocytes - immunology; Monocytes - metabolism; Mutation; Physiological aspects; Protein Binding - immunology; Protein Interaction Domains and Motifs; Proteins; Proteolysis; Recombinant Fusion Proteins; Studies; Vaccines; Viral proteins; Virology; Viruses; United States; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0060126

HIV-1 acquisition can be prevented by broadly neutralizing antibodies (BrNAbs) that target the envelope glycoprotein complex (Env). An ideal vaccine should therefore be able to induce BrNAbs that can provide immunity over a prolonged period of time, but the low intrinsic immunogenicity of HIV-1 Env makes the elicitation of such BrNAbs challenging. Co-stimulatory molecules can increase the immunogenicity of Env and we have engineered a soluble chimeric Env trimer with an embedded granulocyte-macrophage colony-stimulating factor (GM-CSF) domain. This chimeric molecule induced enhanced B and helper T cell responses in mice compared to Env without GM-CSF. We studied whether we could optimize the activity of the embedded GM-CSF as well as the antigenic structure of the Env component of the chimeric molecule. We assessed the effect of truncating GM-CSF, removing glycosylation-sites in GM-CSF, and adjusting the linker length between GM-CSF and Env. One of our designed Env(GM-CSF) chimeras improved GM-CSF-dependent cell proliferation by 6-fold, reaching the same activity as soluble recombinant GM-CSF. In addition, we incorporated GM-CSF into a cleavable Env trimer and found that insertion of GM-CSF did not compromise Env cleavage, while Env cleavage did not compromise GM-CSF activity. Importantly, these optimized Env(GM-CSF) proteins were able to differentiate human monocytes into cells with a macrophage-like phenotype. Chimeric Env(GM-CSF) should be useful for improving humoral immunity against HIV-1 and these studies should inform the design of other chimeric proteins.