Peptide antigen, sequencing

H. Kunz and 1. Miirz, Synthesis of glycopeptides with Lewis antigen side chain and HIV peptide T sequence using the trichloroethoxycaibonal/allyl ester protecting group combination, Synlett p. 591 (1992). 

Order, cellular delivery system or component Cell-specific homing sequence Organelle targeting sequence Signal sequence Cell-penetrating vector Delivery vehicle Order, immunological peptide Antigen... 

Epitopes for T lymphocytes comprise exclusively linear peptide sequences. T lymphocytes are unable to respond to carbohydrate, lipid or nucleic acid material and they only respond to peptide antigen when it is presented to the T lymphocyte by surface proteins on the plasma membrane of host cells. These surface proteins are termed major histocompatibility complex (MHC) proteins and can be subdivided into two main classes. MHC class I proteins are expressed on the surface of all nucleated host cell membranes and present peptide antigen to cytotoxic T lymphocytes. MHC class II proteins are expressed only on a more specialized group of cells termed antigen-presenting cells (APCs), and present peptide antigen to helper T lymphocytes. 

Development of a peptide vaccine is derived from the identification of the immunodominant epitope of an antigen (141). A polypeptide based on the amino acid sequence of the epitope can then be synthesized. Preparation of a peptide vaccine has the advantage of allowing for large-scale production of a vaccine at relatively low cost. It also allows for selecting the appropriate T- or B-ceU epitopes to be included in the vaccine, which may be advantageous in some cases. Several vaccines based on peptide approaches, such as SPf66 (95) for malaria and an HIV-1 peptide (142) have been in clinical trials. No peptide vaccines are Hcensed as yet. 

LDH-x is one of the best characterized antigens and its amino acid sequence is known. A synthetic peptide based on a portion of the molecule has been shown to reduce fertUity in laboratory animals. The nucleotide sequence coding for human LDH-x has been defined and engineered into an expression vector system (121). 

The most frequent application of SPOT-synthesis has been in the preparation of peptide arrays for the identification of linear B-cell epitopes. If the protein antigen is known, a set of overlapping peptides that encompass the entire sequence can be readily synthesized and assayed for binding of antibody (Reineke et al., 1999). The individual residues critical for binding can then be determined by SPOT-synthesis of peptides containing amino acid substitutions. 

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