Conformational study of a short Pertussis toxin T cell epitope incorporated in a multiple antigen peptide template by CD and two-dimensional NMR. Analysis of the structural effects on the activity of synthetic immunogens

Large-scale synthesis and structural analysis of a synthetic glycopeptide dendrimer as an anti-cancer vaccine candidate

A complex glycopeptide was obtained in multigram as a fully synthetic anti-cancer vaccine for human use.

Dendrimers for vaccine and immunostimulatory uses. A review

Dendrimers are well-defined (monodisperse) synthetic globular polymers with a range of interesting chemical and biological properties. Chemical properties include the presence of multiple accessible surface functional groups that can be used for coupling biologically relevant molecules and methods that allow for precise heterofunctionalization of surface groups. Biologically, dendrimers are highly biocompatible and have predictable biodistribution and cell membrane interacting characteristics determined by their size and surface charge. Dendrimers have optimal characteristics to fill the need for efficient immunostimulating compounds (adjuvants) that can increase the efficiency of vaccines, as dendrimers can provide molecularly defined multivalent scaffolds to produce highly defined conjugates with small molecule immunostimulators and/or antigens. The review gives an overview on the use of dendrimers as molecularly defined carriers/presenters of small antigens, including constructs that have built-in immunostimulatory (adjuvant) properties, and as stand-alone adjuvants that can be mixed with antigens to provide efficient vaccine formulations. These approaches allow the preparation of molecularly defined vaccines with highly predictable and specific properties and enable knowledge-based vaccine design substituting the traditional empirically based approaches for vaccine development and production.

Assessment of synthetic peptides for hepatitis A diagnosis using biosensor technology

In the present work we demonstrate the application of a commercial biosensor instrument (BIACORE 1000, Biacore AB, Uppsala) for the detection of antibodies against the hepatitis A virus (HAV) in human serum samples using linear and branched synthetic peptides related to the VP3 capsid protein of HAV. We also studied the conformation of the synthetic peptides by circular dichroism (CD) in order to analyse the changes in secondary structure of the constructs that could influence their recognition by antibodies. Linear and dimeric VP3(110-121) multiple antigen peptides (MAP) were the most sensitive and appropriate for serological studies of serum from HAV infected patients using BIACORE. Immobilization of tetrameric MAPs via amine groups apparently failed to preserve the active conformation of the peptide epitope since it led to lower antibody binding compared to linear and dimeric peptides. The CD analysis showed that the tetrameric MAP constructs tend to adopt a beta-sheet structure due to intermolecular aggregation, which limits epitope accessibility. Our results demonstrate the value of biospecific interaction analysis technology using synthetic peptides for the diagnosis of acute hepatitis A.

The solution structure of the C-terminal segment of tau protein

Pathological changes in the microtubule associated protein tau, leading to tau-containing filamentous lesions, are a major hallmark common to many types of human neurodegenerative diseases, including Alzheimer's disease (AD). No structural data are available which could rationalize the extensive conformational changes that occur when tau protein is converted to Alzheimer's paired helical filaments (PHF). The C-terminal portion of tau plays a crucial role in the aggregation of tau into PHF and in the truncation process that generates cytotoxic segments of tau. Therefore, we investigated the solution structure of the hydrophobic C-terminal segment 423-441 of tau protein (PQLATLADEVSASLAKQGL) by 1H 2D NMR spectroscopy. The peptide displays the typical NMR evidence consistent with a alpha-helix geometry with a stabilizing C-capping motif. The reported data represent the first piece of structural information on an important portion of the molecule and can have implications towards the understanding of its pathophysiology.

Mimicking a conformational B cell epitope of the heat shock protein PfHsp70-1 antigen of Plasmodium falciparum using a multiple antigenic peptide

The Pf72/Hsp70-1 antigen is a major target in the naturally acquired immunity against Plasmodium falciparum malaria. We carried out an extensive analysis of the responses to several epitopes on the least conserved C-terminal domain, according to the mode of sensitization: malaria infection or immunization with different immunogens. We found significant differences in the panel of B-cell epitopes recognized by animal models including primates, and by humans sensitized by natural infection. We focused the analysis on one epitope that is unique to Plasmodium species. It is specifically recognized by a monoclonal antibody that mediates the killing of infected hepatocytes in vitro. We produced a polymeric multiple antigenic peptide (MAP) form of this sequence, which enabled us to identify a new B-cell epitope not detected by ELISA with linear peptides. The polymer was strongly recognized by sera from monkeys or humans sensitized by natural infection, whereas the monomer was not. We modelled the three-dimensional structure of the Pf72/Hsp70-1 sequence, using known Escherischia coli DnaK structures as a template. This predicted that the corresponding region would form a loop in the native antigen. The results presented here suggest that the MAP strategy is also particularly useful as a means of obtaining suitable synthetic models for conformation-dependent epitopes.

Generation of antibodies to human IL-12 and amphiregulin by immunization of Balb/c mice with diepitope multiple antigen peptides

Six peptide sequences derived from the human proteins/oligopeptides IL-12, amphiregulin and FALL-39 were synthesized in order to raise specific antibodies in Balb/c mice. Although peptides are valuable tools for generating specific antibodies, they are often poor immunogens due to their small size and lack of relevant T-cell epitopes. To circumvent these limitations, the human peptides were co-synthesized in diepitope multiple antigen peptides (MAP) with a known H-2d-restricted T helper-cell epitope. The importance of including a T-cell epitope in the diepitope MAPs was demonstrated by the fact that only one of the human peptides was immunogenic as a monoepitope MAP, lacking the T-cell epitope. Conversely, all diepitope MAPs generated potent antibody responses to the desired human peptides as well as to the T-cell epitope. A certain degree of variability of the antibody responses to the diepitope MAPs indicated that the alterable component, i.e. the human B-cell epitope, influenced the T-cell help elicited by the T-cell epitope. Still, the relative conformity of the B-cell responses suggests that this strategy is generally applicable for a rational production of specific antibodies. Moreover, antiserum to four diepitope MAPs recognized the corresponding full-length human protein/oligopeptide as did monoclonal antibodies made against IL-12-and amphiregulin-based MAPs.