Far from the madding crowd: The molecular basis for immunological escape of plasmodium falciparum

Like Thomas Hardy’s famous novel Far from the Madding Crowd, Plasmodium falciparum parasites display their most relevant survival structures (proteins) involved in host cell invasion far away from the immune system’s susceptible regions, displaying tremendous genetic variability, to attract the immune response and escape immune pressure. The 3D structure localisation of the conserved amino acid sequences of this deadly parasite’s most relevant proteins involved in host cell invasion, as well as the location of the highly polymorphic, highly immunogenic regions, clearly demonstrates that such structures are far apart, sometimes 90° to 180° opposite, thereby rendering the immune response useless. It is also shown here that these conserved, functionally-relevant structures are immunologically silent, since no immune response has been induced. © 2017, Caister Academic Press. All rights reserved

The role of pi-interactions and hydrogen bonds in fully protective synthetic malaria vaccine development

Analysis of our Plasmodium falciparum malaria parasite peptides’ 1H-NMR database in the search for H-bonds and ?-interactions led us to correlate their presence or absence with a peptide's particular immunological behavior. It was concluded that a 26.5 ± 1.5 Å between positions 1 to 9 of the HLA-DR?1* interacting region was necessary for proper docking of 20mer-long peptides and these MHC Class II molecules for full-protective immunity. Presence of intramolecular H-bonds or ?-interactions leading to righ-handed ?-helix or ?-turn conformation in this peptide's region induces different immune responses or none. PPIIL conformation and the absence of any intramolecular interaction thus became the first feature characterising our immune protection-inducing structures as malaria vaccine candidates. © 2017 Elsevier Inc

The role of pi-interactions and hydrogen bonds in fully protective synthetic malaria vaccine development

Analysis of our Plasmodium falciparum malaria parasite peptides’ 1H-NMR database in the search for H-bonds and ?-interactions led us to correlate their presence or absence with a peptide's particular immunological behavior. It was concluded that a 26.5 ± 1.5 Å between positions 1 to 9 of the HLA-DR?1* interacting region was necessary for proper docking of 20mer-long peptides and these MHC Class II molecules for full-protective immunity. Presence of intramolecular H-bonds or ?-interactions leading to righ-handed ?-helix or ?-turn conformation in this peptide's region induces different immune responses or none. PPIIL conformation and the absence of any intramolecular interaction thus became the first feature characterising our immune protection-inducing structures as malaria vaccine candidates. © 2017 Elsevier Inc

Towards the development of a fully protective Plasmodium falciparum antimalarial vaccine

If ever there were a truism then it would be that a completely protective Plasmodium falciparum malaria vaccine is desperately needed. Our institute has devoted all its efforts during the last 30 years to developing a fully protective, minimal subunit-based, multiepitope, multistage (targeting sporozoite and merozoite proteins), chemically synthesized antimalarial vaccine, given that peptides with high binding activity to their corresponding host cells (liver cells or red blood cells) form the springboard for vaccine design. However, such conserved high activity binding peptides have to be specifically modified to render them into highly immunogenic and protection-inducing peptides since they are immunologically silent. These modifications, analyzed at the 3D structural level by 1H-NMR, allow them a better fit into the MHC II-peptide-T-cell receptor complex to induce an appropriate immune response, providing a rational and logical approach (analyzed at the single atom level) for vaccine development, particularly in the field of malaria. © 2012 Expert Reviews Ltd

Towards the development of a fully protective Plasmodium falciparum antimalarial vaccine

"If ever there were a truism then it would be that a completely protective Plasmodium falciparum malaria vaccine is desperately needed. Our institute has devoted all its efforts during the last 30 years to developing a fully protective, minimal subunit-based, multiepitope, multistage (targeting sporozoite and merozoite proteins), chemically synthesized antimalarial vaccine, given that peptides with high binding activity to their corresponding host cells (liver cells or red blood cells) form the springboard for vaccine design. However, such conserved high activity binding peptides have to be specifically modified to render them into highly immunogenic and protection-inducing peptides since they are immunologically silent. These modifications, analyzed at the 3D structural level by 1H-NMR, allow them a better fit into the MHC II-peptide-T-cell receptor complex to induce an appropriate immune response, providing a rational and logical approach (analyzed at the single atom level) for vaccine development, particularly in the field of malaria. © 2012 Expert Reviews Ltd.

Protective immunity provided by a new modified SERA protein peptide: Its immunogenetic characteristics and correlation with 3D structure

The serine repeat antigen (SERA) protein is a leading candidate molecule for inclusion as a component in a multi-antigen, multi-stage, minimal subunit-based, chemically synthesised anti-malarial vaccine. Peptides having high red blood cell binding affinity (known as HABPs) have been identified in this protein. The 6733 HABP was located in the C-terminal portion of the 47-kDa fragment while HABP 6754 was located in the C-terminal region of the 56-kDa fragment. These conserved HABPs failed to induce an immune response. Critical red blood cell binding residues and/or their neighbours (assessed by glycine-analogue scanning) were replaced by others having the same mass, volume and surface but different polarity, rendering some of them highly immunogenic when assessed by antibody production against the parasite or its proteins and protection-inducers against experimental challenge with a highly infectious Aotus monkey-adapted Plasmodium falciparum strain. This manuscript presents some modified HABPs as vaccine candidate components for enriching our tailor-made anti-malarial vaccine repertoire, as well as their 3D structure obtained by 1H-NMR displaying a short-structured region, differently from the native ones having random structures. © 2011 Springer-Verlag

Los ángulos Phi (?) y psi (?) involucrados en los enlaces peptídicos de la malaria determinan la inmunidad protectora estéril

Modified HABP (mHABP) regions interacting with HLA-DR?1 molecules have a more restricted conformation and/or sequence than other mHABPs which do not fit perfectly into their peptide binding regions (PBR) and do not induce an acceptable immune response due to the critical role of their ? and ? torsion angles. These angle’s critical role was determined in such highly immunogenic, protection-inducing response against experimental malaria using the conformers (mHABPs) obtained by 1H-NMR and superimposed into HLA-DR?1?-like Aotus monkey molecules; their phi (?) and psi (?) angles were measured and the H-bond formation between these molecules was evaluated. The aforementioned mHABP propensity to assume a regular conformation similar to a left-handed polyproline type II helix (PPIIL) led to suggesting that favouring these conformations according to their amino acid sequence would lead to high antibody titre production and sterile protective immunity induction against malaria, thereby adding new principles or rules for vaccine development, malaria being one of them

The role of pi-interactions and hydrogen bonds in fully protective synthetic malaria vaccine development

Analysis of ourPlasmodium falciparummalaria parasite peptides'1H-NMR database in the search for H-bonds andp-interactions led us to correlate their presence or absence with a peptide's particularimmunological behavior. It was concluded that a 26.5±1.5 Å between positions 1 to 9 of the HLA-DRb1*interacting region was necessary for proper docking of 20mer-long peptides and these MHC Class IImolecules for full-protective immunity. Presence of intramolecular H-bonds orp-interactions leading torigh-handeda-helix orb-turn conformation in this peptide's region induces different immune responsesor none. PPIILconformation and the absence of any intramolecular interaction thus became thefirstfeature characterising our immune protection-inducing structures as malaria vaccine candidate

Protective immunity provided by a new modified SERA protein peptide: Its immunogenetic characteristics and correlation with 3D structure

The serine repeat antigen (SERA) protein is a leading candidate molecule for inclusion as a component in a multi-antigen, multi-stage, minimal subunit-based, chemically synthesised anti-malarial vaccine. Peptides having high red blood cell binding affinity (known as HABPs) have been identified in this protein. The 6733 HABP was located in the C-terminal portion of the 47-kDa fragment while HABP 6754 was located in the C-terminal region of the 56-kDa fragment. These conserved HABPs failed to induce an immune response. Critical red blood cell binding residues and/or their neighbours (assessed by glycine-analogue scanning) were replaced by others having the same mass, volume and surface but different polarity, rendering some of them highly immunogenic when assessed by antibody production against the parasite or its proteins and protection-inducers against experimental challenge with a highly infectious Aotus monkey-adapted Plasmodium falciparum strain. This manuscript presents some modified HABPs as vaccine candidate components for enriching our tailor-made anti-malarial vaccine repertoire, as well as their 3D structure obtained by 1H-NMR displaying a short-structured region, differently from the native ones having random structures. © 2011 Springer-Verlag

Malaria parasite survival depends on conserved binding peptides’ critical biological functions

Biochemical, structural and single amino acid level analysis of 49 Plasmodium falciparum protein regions (13 sporozoite and 36 merozoite proteins) has highlighted the functional role of each conserved high activity binding peptide (cHABP) in cell host-microbe interaction, involving biological functions such as gliding motility, traversal activity, binding invasion, reproduction, nutrient ion transport and the development of severe malaria. Each protein's key function in the malaria parasite's asexual lifecycle (pre-erythrocyte and erythro-cyte) is described in terms of cHABPs; their sequences were located in elegant work published by other groups regarding critical binding regions implicated in malarial parasite invasion. Such cHABPs represent the starting point for developing a logical and rational methodology for selecting an appropriate mixture of modified cHABPs to be used in a completely effective, synthetic antimalarial vaccine. Such methodology could be used for developing vaccines against diseases scourging humanity. © 2016, Caister Academic Press. All rights reserved