Biomedical subjects

Luz M Salazar

Publications and source records attributed to Luz M Salazar.

8 recordsLinked to original sources

PubMed2005

Identifying and characterising the Plasmodium falciparum merozoite surface protein 10 Plasmodium vivax homologue.

Plasmodium vivax malaria is one of the most prevalent parasitic diseases in Asia and Latin-America. The difficulty of maintaining this parasite culture in vitro has hampered identifying and characterising proteins implied in merozoite invasion of red blood cells. We have been able to identify an open reading frame in P. vivax encoding the Plasmodium falciparum merozoite surface protein 10 homologous protein using the partial sequences from this parasite's genome reported during 2004. This new protein contains 479 amino-acids, two epidermal growth factor-like domains, hydrophobic regions at the N- and C-termini, being compatible with a signal peptide and a glycosylphosphatidylinositol anchor site, respectively. The protein is expressed during the parasite's asexual stage and is recognised by polyclonal sera in parasite lysate using Western blot. P. vivax-infected patients' sera highly recognised recombinant protein by ELISA.

Amino Acid Sequence↗

PubMed2004

Plasmodium vivax merozoite surface protein 8 cloning, expression, and characterisation.

Plasmodium vivax, one of the four parasite species causing malaria in humans, is the most widespread throughout the world, leading to nearly 80 million cases per year, mainly in Latin-America and Asia. An open reading frame encoding the Plasmodium falciparum merozoite surface protein 8 P. vivax homologue has been identified in the present study by screening the current data obtained from this parasite's partially sequenced genome. This new protein contains 487 amino-acids, two epidermal growth factor like domains, hydrophobic regions at the N- and C-termini compatible with a signal peptide, and a glycosylphosphatidylinositol anchor site, respectively. This gene's transcription and its encoded protein expression have been assessed, as well as its recognition by P. vivax-infected patients' sera. Based on this recognition, and a previous study showing that mice immunised with the Plasmodium yoelii homologous protein were protected, we consider the PvMSP8 a good candidate to be included in a multi-stage multi-antigen P. vivax vaccine.

Amino Acid Motifs↗

PubMed2004

Identifying and structurally characterizing CD1b in Aotus nancymaae owl monkeys.

This study reports the molecular characterization and tissue expression of the non-human Aotus nancymaae primate CD1b isoform in the search for an experimental animal model to be used in evaluating the role of non-peptide antigen-presentation molecules in the immune response to infectious agents. CD1b expression on the surface of A. nancymaae peripheral blood monocyte-derived dendritic cells, shown by flow cytometry, was made possible by using human CD1b isoform antibodies. Studying the expression of CD1b-encoded transcripts revealed this molecule's broad distribution in several tissues. The A. nancymaae CD1b transcript-encoded amino-acid sequence showed 95.5% identity with the human sequence. Such high sequence homology was reflected in the identical structural conservation of how pockets A', C' and F' and tunnel T' conforming the antigen's binding site are organized, the similar arrangement of those amino-acids interacting with the T-cell receptor (TCR) during antigen presentation, and the conservation of YQNI-motif sequence in the cytoplasmatic tail (responsible for the molecule's intracellular trafficking in humans). Comparing the structure of human CD1a and CD1b and mouse CD1d proteins with CD1b structure in A. nancymaae obtained by minimization revealed that changes in the latter molecule's alpha1 and alpha2 domains imposed a narrowing of the antigen-binding groove in A. nancymaae CD1b. The high structural similarity between A. nancymaae CD1b and that from humans presented in this study leads to A. nancymaae being proposed as a suitable experimental animal model for analyzing CD1b in vivo, mainly in bacterial and parasite infections such as tuberculosis and malaria, respectively.

Amino Acid Sequence↗

PubMed2004

Changing ABRA protein peptide to fit into the HLA-DRbeta1*0301 molecule renders it protection-inducing.

The Plasmodium falciparum acidic-basic repeat antigen represents a potential malarial vaccine candidate. One of this protein's high activity binding peptides, named 2150 ((161)KMNMLKENVDYIQKNQNLFK(180)), is conserved, non-immunogenic, and non-protection-inducing. Analogue peptides whose critical binding residues (in bold) were replaced by amino-acids having similar mass but different charge were synthesized and tested to try to modify such immunological properties. These analogues' HLA-DRbeta1* molecule binding ability were also studied in an attempt to explain their biological mechanisms and correlate binding capacity and immunological function with their three-dimensional structure determined by (1)H NMR. A 3(10) distorted helical structure was identified in protective and immunogenic peptide 24922 whilst alpha-helical structure was found for non-immunogenic, non-protective peptides having differences in alpha-helical position. The changes performed on immunogenic, protection-inducing peptide 24922 allowed it to bind specifically to the HLA-DRbeta1*0301 molecule, suggesting that these changes may lead to better interaction with the MHC Class II-peptide-TCR complex rendering it immunogenic and protective, thus suggesting a new way of developing multi-component, sub-unit-based anti-malarial vaccines.

Amino Acid Sequence↗

PubMed2003

An alpha helix conformationally restricted peptide is recognized by cervical carcinoma patients' sera.

Human papillomavirus type 16 (HPV-16) represents the major cervical carcinoma associated virus among women, especially in Colombia. It has thus become important to develop reliable inexpensive tests for detecting the presence of this virus. It has been shown that HPV16-E7 oncoprotein structural features have three alpha-helical structures and a loop-like structure. The hydrazone link approach was used to mimic helix secondary substructures. Sera from women with invasive cervical carcinoma were tested against conformationally restricted peptides and their respective linear peptides to identify conformational epitopes. One peptide that was conformationally restricted to an alpha-helix showed very strong positive reaction with sera from women having invasive cervical carcinoma; there was no reaction with sera from patients with other carcinomas, children, or healthy women. NMR studies confirmed this peptide's alpha-helical structure. The observation that constrained protein substructure peptidomimetics can identify new conformationally sensitive antibodies in cervical carcinoma patients' sera is very important, since these antibodies are almost all generated by native proteins, providing a new selection of antibodies for diagnostic and vaccine studies.

Child↗

PubMed2003

Modified merozoite surface protein-1 peptides with short alpha helical regions are associated with inducing protection against malaria.

The merozoite surface protein-1 represents a prime candidate for development of a malaria vaccine. Merozoite surface protein-1 has been shown to demonstrate high-activity peptide binding to human red blood cells. One of the high-activity binding peptides, named 5501, located in the N-terminus (amino acid sequence MLNISQHQCVKKQCPQNS) of the 19-kDa molecular mass fragment of merozoite surface protein-1, is conserved, nonimmunogenic and nonprotective. Its critical binding residues were identified and replaced with amino acids of similar mass but different charge, in order to modify their immunogenic and protective characteristics. Three analogues with positive or negative immunological results were studied by nuclear magnetic resonance to correlate their three-dimensional structure with their biological functions. The studied peptides presented alpha-helical fragments, but in different peptide regions and extensions, except for randomly structured 5501. We show that altering a few amino acids induced immunogenicity and protectivity against experimental malaria and changed the peptide three-dimensional structure, suggesting a better fit with immune-system molecules.

Amino Acid Sequence↗

PubMed2002

1H-NMR structures of the Plasmodium falciparum 1758 erythrocyte binding peptide analogues and protection against malaria.

A conserved high activity erythrocyte binding peptide (HAEBP) derived from the 175-erythrocyte binding antigen (EBA-175), coded 1758, was synthesized and analyzed for antigenic and protective activities in Aotus monkeys, together with several of its analogues. Conformational analysis by 1H Nuclear Magnetic Resonance in TFE-solution was done for some of them, as well as the 1758 parent peptide. We show that the conserved 1758 HAEBP (being neither immunogenic nor protective) has an alpha helical structure, whilst its analogues contain beta-turn structures. The 13790 peptide (highly immunogenic and protective for some monkeys) shows a type I beta-turn structure distorted in psi(i + 1) psi(i + 2) angles, whilst immunogenic and non-protective (as well as the non-immunogenic and non-protective peptides) have type III' beta-turns. An understanding of native peptide's correlation with altered peptide three-dimensional structure and resulting immunogenicity and protective activity may lead to a more rational design of multi-antigenic, multi-stage P. falciparum subunit based malaria vaccines.

Amino Acid Sequence↗

PubMed2002

Protection against experimental malaria associated with AMA-1 peptide analogue structures.

One Plasmodium falciparum malaria antigen is an integral membrane protein called apical membrane antigen-1. High activity binding peptides to human red blood cells have been identified in this protein. 4337 is a conserved, non-immunogenic peptide with high activity red blood cell binding and its critical residues have already been identified. Peptide analogues (with amino acids having the same mass but different charge) were generated to change their immunogenic and protective characteristics. Three analogues having positive or negative immunological results were studied by nuclear magnetic resonance. The studied peptides all had an alpha-helix fragment, but in different peptide regions and extensions, except for randomly structured 4337. We show that altering a few amino acids induced immunogenicity and protectivity against experimental malaria and changed their three-dimensional structure, suggesting a better fit with immune system molecules and that modified peptides having better immunological properties can be included in the design of new malaria multi-component subunit-based vaccine.

Amino Acid Sequence↗