Rational Design of an HIV-1 Vaccine using a Filamentous Phage Carrier

• Author / Creator

  Bailey, Justin, J.

• Glycans are a diverse and integral component of all biological organisms, making them an ideal target for vaccine development. Carbohydrates often act as weak antigens, lacking the T cell epitopes required to recruit T cell help which is vital to develop a strong and long lasting protective antibody response. Chemical conjugation of glycan antigens to a protein carrier to elicit T cell help has been a successful strategy to improve the strength of the immune response towards glycan-derived haptens. The hapten-carrier concept has been successfully used for numerous synthetic glycoconjugate vaccines now approved for human use.
  HIV-1 appears to be an ideal candidate for developing a glycoconjugate vaccine as the exposed HIV-1 envelope protein, gp120, is one of the most heavily N-glycosylated proteins known. Glycoconjugate vaccines displaying the glycans of gp120 have thus far failed to elicit protective antibodies that bind to gp120 or neutralize viruses bearing HIV 1 Env. The lack of cross reactivity has been attributed to an inability of the glycoconjugate vaccines to faithfully mimic the carbohydrate-dense gp120 surface.
  Described herein is the synthesis of two mannosyl thiol analogues of gp120 glycans, their chemical conjugation to a filamentous phage carrier, and the LC-UV-MS methodology developed to characterize the resulting glycoconjugates. The mannosyl thiols provide access to highly reactive linker chemistry while maintaining a minimal linker length, which may be essential to mimic the limited flexibility of the tightly packed glycans of gp120. Filamentous phage possess a structurally homogenous, repeating surface with closely spaced, solvent exposed amines available for conjugation. This arrangement is ideal for mimicking the glycan shield of gp120. Coupling of mannosyl thiol analogues to the phage carrier produced a densely glycosylated surface where over 80% of the 8,100+ conjugation sites of the phage were occupied, as was determined to an unprecedented level of clarity by LC-UV-MS. The phage glycoconjugates were shown to interact with anti-HIV-1 glycan-specific antibody 2G12 with 0.5 nM affinity, ranking it as one of the best 2G12-binding antigenic mimics described thus far. Mice immunized with the phage glycoconjugates elicited high titres of carbohydrate-specific antibodies that were unable to cross react with gp120.

• Subjects / Keywords

  • Glycoconjugate vaccine
  • HIV-1
  • Filamentous phage

• Graduation date

  Spring 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R33F4KW7V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.