High affinity mimotope of the polysaccharide capsule of Cryptococcus neoformans identified from an evolutionary phage peptide library
| Autor: | Rena J. May, David O. Beenhouwer, Matthew D. Scharff, Philippe Valadon |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Phage display
Antigens Fungal medicine.drug_class Immunology Molecular Sequence Data chemical and pharmacologic phenomena Biology Monoclonal antibody Epitope Microbiology Evolution Molecular Mice Meningoencephalitis Peptide Library Polysaccharides medicine Tetanus Toxoid Immunology and Allergy Animals Amino Acid Sequence Peptide library Antibodies Fungal Cryptococcus neoformans Mice Inbred BALB C Base Sequence Mimotope Molecular Mimicry Toxoid Antibodies Monoclonal Cryptococcosis biology.organism_classification Virology carbohydrates (lipids) DNA-Binding Proteins biology.protein Capsid Proteins Binding Sites Antibody Fungal Vaccines Peptides Viral Fusion Proteins Keyhole limpet hemocyanin Injections Intraperitoneal Bacteriophage M13 |
| Zdroj: | Journal of immunology (Baltimore, Md. : 1950). 169(12) |
| ISSN: | 0022-1767 |
| Popis: | Cryptococcus neoformans causes a life-threatening meningoencephalitis in a significant percentage of AIDS patients. Mice immunized with a glycoconjugate vaccine composed of the glucuronoxylomannan (GXM) component of the cryptococcal capsular polysaccharide conjugated to tetanus toxoid (TT) produce Abs that, based on the epitope recognized, can be either protective or nonprotective. Since nonprotective Abs block the efficacy of protective Abs, we are interested in developing a vaccine that would focus the immune response specifically to protective epitopes. Previously, we screened a phage display library with 2H1, a protective anti-GXM mAb, and isolated PA1, a representative peptide that had a Kd of 295 nM for 2H1. Mice immunized with PA1 conjugated to keyhole limpet hemocyanin developed high anti-peptide (1/13,000), but low anti-GXM (maximum, 1/200) titers. We now report our efforts to improve this vaccine by screening a sublibrary with six random amino acids added to either end of the PA1 motif to identify higher affinity peptides. P206.1, a peptide isolated from this sublibrary, had 80-fold higher affinity for 2H1 (Kd = 3.7 nM) than PA1. P206.1 bound protective, but not nonprotective, anti-GXM Abs. Mice immunized with P206.1 conjugated to various carriers did not mount an Ab response to GXM despite developing high anti-peptide titers. However, mice primed with GXM-TT and boosted with P206.1-TT developed significant anti-GXM titers (maximum, 1/180,000). This latter immunization scheme focused the immune response on protective epitopes, since only 2–5% of these titers were directed against nonprotective de-O-acetylated GXM epitopes compared with 20–60% in animals primed and boosted with GXM-TT. |
| Databáze: | OpenAIRE |
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