Refocusing antibody responses by chemical modification of vaccine antigens
<p>The envelope glycoprotein (Env) of Human Immunodeficiency Virus 1 (HIV-1) has developed several immune-evasion mechanisms to avoid the induction of neutralising antibodies, including immunodominant non-neutralising epitopes, conformational flexibility of conserved epitopes, and spontaneous...
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| Format: | Thesis |
| Language: | English |
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2014
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| _version_ | 1826316134394101760 |
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| author | Schiffner, T |
| author2 | Sattentau, Q |
| author_facet | Sattentau, Q Schiffner, T |
| author_sort | Schiffner, T |
| collection | OXFORD |
| description | <p>The envelope glycoprotein (Env) of Human Immunodeficiency Virus 1 (HIV-1) has developed several immune-evasion mechanisms to avoid the induction of neutralising antibodies, including immunodominant non-neutralising epitopes, conformational flexibility of conserved epitopes, and spontaneous subunit dissociation, thus impeding vaccine development. Here, chemical modification of Env-based vaccine antigens is explored to overcome these obstacles.</p> <p>Firstly, covalent fixation of Env by chemical cross-linking was used to stabilise the conformationally flexible structure and prevent subunit dissociation. Cross-linked Env constructs showed reduced binding of many non-neutralising antibodies whilst largely maintaining antibody recognition by broadly neutralising antibodies. Compared to unmodified material, immunisation with some of these cross-linked proteins led to the induction of significantly increased antibody titres targeting the conserved CD4 binding site of Env despite similar overall antibody titres. These refocused antibody responses resulted in increased serum neutralising titres compared to animals receiving unmodified protein.</p> <p>Secondly, an epitope masking strategy was developed to reduce or eliminate the immunogenicity of neutralisation-irrelevant surfaces. This was achieved using site-selective addition of theoretically immunosilent glycoconjugates to lysine residues. Masking of model protein hen egg lysozyme (HEL) led to site-selective loss of antibody binding to the modification sites <em>in vitro</em>, which translated into refocusing of antibody responses from masked to unmasked epitopes <em>in vivo</em>. Mutant HIV-1 and influenza virus surface glycoproteins were designed that had lysine residues removed from close proximity to the respective broadly neutralising epitopes, but added throughout the remaining surface. Masking of these mutant proteins with second-generation glycoconjugates led to predictable perturbations of antibody binding <em>in vitro</em>. However, administration of these modified glycoproteins revealed unexpectedly that the masking glycans were highly immunogenic <em>in vivo</em>. Thus, this strategy may well prove useful if truly non-immunogenic glycoconjugates can be identified.</p> <p>Taken together, these chemical modifications of vaccine antigens may allow focused targeting of specific antigenic regions for increased B cell recognition, and may thus be a valuable tool for vaccine antigen design.</p> |
| first_indexed | 2024-03-06T20:12:52Z |
| format | Thesis |
| id | oxford-uuid:2b2cac0f-6be3-4f91-96e5-9888e02780d4 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:38:22Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | oxford-uuid:2b2cac0f-6be3-4f91-96e5-9888e02780d42024-12-07T09:59:54ZRefocusing antibody responses by chemical modification of vaccine antigensThesishttp://purl.org/coar/resource_type/c_db06uuid:2b2cac0f-6be3-4f91-96e5-9888e02780d4PathologyBiology (medical sciences)ImmunologyDisease preventionGlycobiologyBiologyBiochemistryInfectious diseasesHIV/AIDSVirusesVaccinologyMedical sciencesEnglishOxford University Research Archive - Valet2014Schiffner, TSattentau, Q<p>The envelope glycoprotein (Env) of Human Immunodeficiency Virus 1 (HIV-1) has developed several immune-evasion mechanisms to avoid the induction of neutralising antibodies, including immunodominant non-neutralising epitopes, conformational flexibility of conserved epitopes, and spontaneous subunit dissociation, thus impeding vaccine development. Here, chemical modification of Env-based vaccine antigens is explored to overcome these obstacles.</p> <p>Firstly, covalent fixation of Env by chemical cross-linking was used to stabilise the conformationally flexible structure and prevent subunit dissociation. Cross-linked Env constructs showed reduced binding of many non-neutralising antibodies whilst largely maintaining antibody recognition by broadly neutralising antibodies. Compared to unmodified material, immunisation with some of these cross-linked proteins led to the induction of significantly increased antibody titres targeting the conserved CD4 binding site of Env despite similar overall antibody titres. These refocused antibody responses resulted in increased serum neutralising titres compared to animals receiving unmodified protein.</p> <p>Secondly, an epitope masking strategy was developed to reduce or eliminate the immunogenicity of neutralisation-irrelevant surfaces. This was achieved using site-selective addition of theoretically immunosilent glycoconjugates to lysine residues. Masking of model protein hen egg lysozyme (HEL) led to site-selective loss of antibody binding to the modification sites <em>in vitro</em>, which translated into refocusing of antibody responses from masked to unmasked epitopes <em>in vivo</em>. Mutant HIV-1 and influenza virus surface glycoproteins were designed that had lysine residues removed from close proximity to the respective broadly neutralising epitopes, but added throughout the remaining surface. Masking of these mutant proteins with second-generation glycoconjugates led to predictable perturbations of antibody binding <em>in vitro</em>. However, administration of these modified glycoproteins revealed unexpectedly that the masking glycans were highly immunogenic <em>in vivo</em>. Thus, this strategy may well prove useful if truly non-immunogenic glycoconjugates can be identified.</p> <p>Taken together, these chemical modifications of vaccine antigens may allow focused targeting of specific antigenic regions for increased B cell recognition, and may thus be a valuable tool for vaccine antigen design.</p> |
| spellingShingle | Pathology Biology (medical sciences) Immunology Disease prevention Glycobiology Biology Biochemistry Infectious diseases HIV/AIDS Viruses Vaccinology Medical sciences Schiffner, T Refocusing antibody responses by chemical modification of vaccine antigens |
| title | Refocusing antibody responses by chemical modification of vaccine antigens |
| title_full | Refocusing antibody responses by chemical modification of vaccine antigens |
| title_fullStr | Refocusing antibody responses by chemical modification of vaccine antigens |
| title_full_unstemmed | Refocusing antibody responses by chemical modification of vaccine antigens |
| title_short | Refocusing antibody responses by chemical modification of vaccine antigens |
| title_sort | refocusing antibody responses by chemical modification of vaccine antigens |
| topic | Pathology Biology (medical sciences) Immunology Disease prevention Glycobiology Biology Biochemistry Infectious diseases HIV/AIDS Viruses Vaccinology Medical sciences |
| work_keys_str_mv | AT schiffnert refocusingantibodyresponsesbychemicalmodificationofvaccineantigens |