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1.
Brief Bioinform ; 22(6)2021 11 05.
Artículo en Inglés | MEDLINE | ID: mdl-33979434

RESUMEN

Experimentally estimating peptide-major histocompatibility complex (pMHC) binding affinity has been quite challenging due to the many receptors and the many potential ligands implicated in it. We have thus proposed a straightforward computational methodology considering the different mechanisms involved in pMHC binding to facilitate studying such receptor-ligand interactions. We have developed a pipeline using semi-empirical quantum mechanical methods for calculating pMHC class I and II molecules' binding energy (BE). This pipeline can systematize the methodology for calculating pMHC system BE, enabling the rational design of T-cell epitopes to be used as pharmaceuticals and vaccines.


Asunto(s)
Biología Computacional/métodos , Antígenos de Histocompatibilidad/química , Modelos Moleculares , Oligopéptidos/química , Teoría Cuántica , Programas Informáticos , Algoritmos , Secuencia de Aminoácidos , Antígenos de Histocompatibilidad/inmunología , Antígenos de Histocompatibilidad/metabolismo , Humanos , Ligandos , Oligopéptidos/inmunología , Oligopéptidos/metabolismo , Unión Proteica , Relación Estructura-Actividad
2.
Int J Med Microbiol ; 313(3): 151579, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-37030083

RESUMEN

Plasmodium falciparum-related malaria represents a serious worldwide public health problem due to its high mortality rates. P. falciparum expresses rhoptry neck protein 4 (PfRON4) in merozoite and sporozoite rhoptries, it participates in tight junction-TJ formation via the AMA-1/RON complex and is refractory to complete genetic deletion. Despite this, which PfRON4 key regions interact with host cells remain unknown; such information would be useful for combating falciparum malaria. Thirty-two RON4 conserved region-derived peptides were chemically synthesised for determining and characterising PfRON4 regions having high host cell binding affinity (high activity binding peptides or HABPs). Receptor-ligand interaction/binding assays determined their specific binding capability, the nature of their receptors and their ability to inhibit in vitro parasite invasion. Peptides 42477, 42479, 42480, 42505 and 42513 had greater than 2% erythrocyte binding activity, whilst peptides 42477 and 42480 specifically bound to HepG2 membrane, both of them having micromolar and submicromolar range dissociation constants (Kd). Cell-peptide interaction was sensitive to treating erythrocytes with trypsin and/or chymotrypsin and HepG2 with heparinase I and chondroitinase ABC, suggesting protein-type (erythrocyte) and heparin and/or chondroitin sulphate proteoglycan receptors (HepG2) for PfRON4. Erythrocyte invasion inhibition assays confirmed HABPs' importance during merozoite invasion. PfRON4 800-819 (42477) and 860-879 (42480) regions specifically interacted with host cells, thereby supporting their inclusion in a subunit-based, multi-antigen, multistage anti-malarial vaccine.


Asunto(s)
Malaria , Plasmodium falciparum , Animales , Humanos , Plasmodium falciparum/genética , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , Proteínas Portadoras/metabolismo , Péptidos , Eritrocitos/parasitología , Unión Proteica , Merozoítos/metabolismo , Hepatocitos/metabolismo , Antígenos de Protozoos
3.
Biochem Biophys Res Commun ; 534: 86-93, 2021 01 01.
Artículo en Inglés | MEDLINE | ID: mdl-33316544

RESUMEN

This work describes a methodology for developing a minimal, subunit-based, multi-epitope, multi-stage, chemically-synthesised, anti-Plasmodium falciparum malaria vaccine. Some modified high activity binding peptides (mHABPs) derived from functionally relevant P. falciparum MSP, RH5 and AMA-1 conserved amino acid regions (cHABPs) for parasite binding to and invasion of red blood cells (RBC) were selected. They were highly immunogenic as assessed by indirect immunofluorescence (IFA) and Western blot (WB) assays and protective immune response-inducers against malarial challenge in the Aotus monkey experimental model. NetMHCIIpan 4.0 was used for predicting peptide-Aotus/human major histocompatibility class II (MHCII) binding affinity in silico due to the similarity between Aotus and human immune system molecules; ∼50% of Aotus MHCII allele molecules have a counterpart in the human immune system, being Aotus-specific, whilst others enabled recognition of their human counterparts. Some peptides' 1H-NMR-assessed structural conformation was determined to explain residue modifications in mHABPs inducing secondary structure changes. These directly influenced immunological behaviour, thereby highlighting the relationship with MHCII antigen presentation. The data obtained in such functional, immunological, structural and predictive approach suggested that some of these peptides could be excellent components of a fully-protective antimalarial vaccine.


Asunto(s)
Eritrocitos/parasitología , Vacunas contra la Malaria/farmacología , Plasmodium falciparum/patogenicidad , Animales , Antígenos de Protozoos/química , Aotidae , Proteínas Portadoras/química , Epítopos , Eritrocitos/efectos de los fármacos , Antígenos de Histocompatibilidad Clase II/metabolismo , Interacciones Huésped-Parásitos/efectos de los fármacos , Humanos , Espectroscopía de Resonancia Magnética , Vacunas contra la Malaria/inmunología , Vacunas contra la Malaria/metabolismo , Malaria Falciparum/inmunología , Malaria Falciparum/prevención & control , Péptidos/inmunología , Péptidos/metabolismo , Proteínas Protozoarias/química , Vacunas de Subunidad/inmunología , Vacunas de Subunidad/farmacología
4.
Mem Inst Oswaldo Cruz ; 116: e200587, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34287503

RESUMEN

BACKGROUND: The inappropriate use of antibiotics has led to the accelerated growth of resistance to antibiotics. The search for new therapeutic strategies (i.e., antimicrobial peptides-AMPs) has thus become a pressing need. OBJECTIVE: Characterising and evaluating Sarconesiopsis magellanica larval fat body-derived AMPs. METHODS: Fat body extracts were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC); mass spectrometry was used for characterising the primary structure of the AMPs so found. ProtParam (Expasy) was used for analysing the AMPs' physico-chemical properties. Synthetic AMPs' antibacterial activity was evaluated. FINDINGS: Four new AMPs were obtained and called sarconesin III, IV, V and VI. Sarconesin III had an α-helix structure and sarconesins IV, V and VI had linear formations. Oligomer prediction highlighted peptide-peptide interactions, suggesting that sarconesins III, V and VI could form self-aggregations when in contact with the microbial membrane. AMPs synthesised from their native molecules' sequences had potent activity against Gram-positive bacteria and, to a lesser extent, against Gram-negative and drug-resistant bacteria. Sarconesin VI was the most efficient AMP. None of the four synthetic AMPs had a cytotoxic effect. MAIN CONCLUSIONS: S. magellanica larval fat body-derived antimicrobial peptides are an important source of AMPs and could be used in different antimicrobial therapies and overcoming bacterial resistance.


Asunto(s)
Dípteros , Animales , Antibacterianos/farmacología , Calliphoridae , Cuerpo Adiposo , Larva , Pruebas de Sensibilidad Microbiana , Proteínas Citotóxicas Formadoras de Poros
5.
Int J Mol Sci ; 22(23)2021 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-34884666

RESUMEN

Congenital long QT syndrome (LQTS) is a cardiac channelopathy characterized by a prolongation of the QT interval and T-wave abnormalities, caused, in most cases, by mutations in KCNQ1, KCNH2, and SCN5A. Although the predominant pattern of LQTS inheritance is autosomal dominant, compound heterozygous mutations in genes encoding potassium channels have been reported, often with early disease onset and more severe phenotypes. Since the molecular mechanisms underlying severe phenotypes in carriers of compound heterozygous mutations are unknown, it is possible that these compound mutations lead to synergistic or additive alterations to channel structure and function. In this study, all-atom molecular dynamic simulations of KCNQ1 and hERG channels were carried out, including wild-type and channels with compound mutations found in two patients with severe LQTS phenotypes and limited family history of the disease. Because channels can likely incorporate different subunit combinations from different alleles, there are multiple possible configurations of ion channels in LQTS patients. This analysis allowed us to establish the structural impact of different configurations of mutant channels in the activated/open state. Our data suggest that channels with these mutations show moderate changes in folding energy (in most cases of stabilizing character) and changes in channel mobility and volume, differentiating them from each other and from WT. This would indicate possible alterations in K+ ion flow. Hetero-tetrameric mutant channels showed intermediate structural and volume alterations vis-à-vis homo-tetrameric channels. These findings support the hypothesis that hetero-tetrameric channels in patients with compound heterozygous mutations do not necessarily lead to synergistic structural alterations.


Asunto(s)
Canalopatías/genética , Canal de Potasio ERG1/metabolismo , Canal de Potasio KCNQ1/metabolismo , Síndrome de QT Prolongado/genética , Simulación de Dinámica Molecular , Niño , Preescolar , Canal de Potasio ERG1/genética , Humanos , Canal de Potasio KCNQ1/genética , Masculino
6.
Biochem Biophys Res Commun ; 527(4): 1021-1026, 2020 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-32439169

RESUMEN

Malaria remains a large-scale public health problem, killing more than 400,000 people and infecting up to 230 million worldwide, every year. Unfortunately, despite numerous efforts and research concerning vaccine development, results to date have been low and/or strain-specific. This work describes a strategy involving Plasmodium falciparum Duffy binding-like (DBL) and reticulocyte-binding protein homologue (RH) family-derived minimum functional peptides, netMHCIIpan3.2 parental and modified peptides' in silico binding prediction and modeling some Aotus major histocompatibility class II (MHCII) molecules based on known human molecules' structure to understand their differences. These are used to explain peptides' immunological behaviour when used as vaccine components in the Aotus model. Despite the great similarity between human and Aotus immune system molecules, around 50% of Aotus allele molecules lack a counterpart in the human immune system which could lead to an Aotus-specific vaccine. It was also confirmed that functional Plasmodium falciparum' conserved proteins are immunologically silent (in both the animal model and in-silico prediction); they must therefore be modified to elicit an appropriate immune response. Some peptides studied here had the desired behaviour and can thus be considered components of a fully-protective antimalarial vaccine.


Asunto(s)
Vacunas contra la Malaria/inmunología , Malaria Falciparum/prevención & control , Plasmodium falciparum/inmunología , Proteínas Protozoarias/inmunología , Vacunas de Subunidad/inmunología , Secuencia de Aminoácidos , Animales , Aotidae , Control de Enfermedades Transmisibles , Enfermedades Transmisibles/inmunología , Modelos Animales de Enfermedad , Antígenos de Histocompatibilidad Clase II/inmunología , Humanos , Vacunas contra la Malaria/química , Vacunas contra la Malaria/uso terapéutico , Malaria Falciparum/inmunología , Modelos Moleculares , Plasmodium falciparum/química , Proteínas Protozoarias/química , Proteínas Protozoarias/uso terapéutico , Vacunas de Subunidad/química , Vacunas de Subunidad/uso terapéutico
7.
Cell Immunol ; 347: 103999, 2020 01.
Artículo en Inglés | MEDLINE | ID: mdl-31733823

RESUMEN

We are currently living the advent of a new age for medicine in which basic research is being quickly translated into marketable drugs, and the widespread access to genomics data is allowing the design and implementation of personalized solutions to medical conditions. Non-human primates (NHP) have gained an essential role in drug discovery and safety testing due to their close phylogenetic relationship to humans. In this study, a collection of well characterized genes of the human immune system was used to define the orthology-based immunome in four NHP species, with carefully curated annotations available based on multi-tissue RNA-seq datasets. A broad variation in the frequency of expressed protein isoforms was observed between species. Finally, this analysis also revealed the lack of expression of at least four different chemokines in new-world primates. In addition, transcripts corresponding to four genes including interleukin 12 subunit alpha were expressed in humans but no other primate species analyzed. Access to the non-human primate immunome is available in http://www.fidic.org.co:90/proyecto/.


Asunto(s)
Quimiocinas/genética , Bases de Datos de Ácidos Nucleicos , Bases de Datos de Proteínas , Subunidad p35 de la Interleucina-12/genética , Primates/genética , Investigación Biomédica Traslacional/métodos , Animales , Aotidae/genética , Callithrix/genética , Diseño de Fármacos , Descubrimiento de Drogas/métodos , Humanos , Sistema Inmunológico , Macaca mulatta/genética , Modelos Animales , Pan troglodytes/genética , Isoformas de Proteínas/genética
8.
J Chem Inf Model ; 59(12): 5148-5160, 2019 12 23.
Artículo en Inglés | MEDLINE | ID: mdl-31747514

RESUMEN

Estimating peptide-major histocompatibility complex (pMHC) binding using structural computational methods has an impact on understanding overall immune function triggering adaptive immune responses in MHC class II molecules. We developed a strategy for optimizing pMHC structure interacting with water molecules and for calculating the binding energy of receptor + ligand systems, such as HLA-DR1 + HA, HLA-DR1 + CLIP, HLA-DR2 + MBP, and HLA-DR3 + CLIP, as well as a monosubstitution panel. Taking pMHC's structural properties, we assumed that ΔH ≫ -TΔS would generate a linear model for estimating relative free energy change, using three semiempirical quantum methods (PM6, PM7, and FMO-SCC-DFTB3) along with the implicit solvent models, and considering proteins in neutral and charged states. Likewise, we confirmed our approach's effectiveness in calculating binding energies having high correlation with experimental data and low root-mean-square error (<2 kcal/mol). All in all, our pipeline differentiates weak from strong peptide binders as a reliable method for studying pMHC interactions.


Asunto(s)
Antígenos de Histocompatibilidad Clase II/metabolismo , Modelos Moleculares , Péptidos/metabolismo , Teoría Cuántica , Antígenos de Histocompatibilidad Clase II/química , Unión Proteica , Conformación Proteica , Termodinámica
9.
Molecules ; 24(11)2019 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-31159162

RESUMEN

Antibiotic resistance is at dangerous levels and increasing worldwide. The search for new antimicrobial drugs to counteract this problem is a priority for health institutions and organizations, both globally and in individual countries. Sarconesiopsis magellanica blowfly larval excretions and secretions (ES) are an important source for isolating antimicrobial peptides (AMPs). This study aims to identify and characterize a new S. magellanica AMP. RP-HPLC was used to fractionate ES, using C18 columns, and their antimicrobial activity was evaluated. The peptide sequence of the fraction collected at 43.7 min was determined by mass spectrometry (MS). Fluorescence and electronic microscopy were used to evaluate the mechanism of action. Toxicity was tested on HeLa cells and human erythrocytes; physicochemical properties were evaluated. The molecule in the ES was characterized as sarconesin II and it showed activity against Gram-negative (Escherichia coli MG1655, Pseudomonas aeruginosa ATCC 27853, P. aeruginosa PA14) and Gram-positive (Staphylococcus aureus ATCC 29213, Micrococcus luteus A270) bacteria. The lowest minimum inhibitory concentration obtained was 1.9 µM for M. luteus A270; the AMP had no toxicity in any cells tested here and its action in bacterial membrane and DNA was confirmed. Sarconesin II was documented as a conserved domain of the ATP synthase protein belonging to the Fli-1 superfamily. The data reported here indicated that peptides could be alternative therapeutic candidates for use in infections against Gram-negative and Gram-positive bacteria and eventually as a new resource of compounds for combating multidrug-resistant bacteria.


Asunto(s)
Péptidos Catiónicos Antimicrobianos/biosíntesis , Péptidos Catiónicos Antimicrobianos/farmacología , Dípteros/metabolismo , Secuencia de Aminoácidos , Animales , Antibacterianos/biosíntesis , Antibacterianos/química , Antibacterianos/aislamiento & purificación , Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/aislamiento & purificación , Bacterias/efectos de los fármacos , Fenómenos Químicos , Cromatografía Líquida de Alta Presión , Relación Dosis-Respuesta a Droga , Espectrometría de Masas , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Conformación Proteica , Relación Estructura-Actividad
10.
Curr Issues Mol Biol ; 22: 65-78, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-27698284

RESUMEN

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 induce.


Asunto(s)
Interacciones Huésped-Parásitos/inmunología , Malaria Falciparum/inmunología , Plasmodium falciparum/inmunología , Animales , Antígenos de Protozoos/inmunología
11.
Biochem Biophys Res Commun ; 489(3): 339-345, 2017 07 29.
Artículo en Inglés | MEDLINE | ID: mdl-28549586

RESUMEN

A vaccine candidate component must fit perfectly into the antigen presenting HLA-DRß* molecule's groove (or canonical nonapeptide) peptide binding region (PBR) during antigen presentation to the T-cell receptor (TCR), conforming a specific and stable macromolecular complex and induce an appropriate immune response. Antigen's peripheral flanking residues (PFR, positions (p) -p2 and p10) must thus establish strong interactions with the HLA-DRß* - TCR complex. These amino acids (aa) have specific physico-chemical characteristics enabling differentiation between non-protective but antibody-inducer (NPAI), short-lived protection inducer (SLPI) and long-lasting protection inducer (LLPI) peptides when used as an antimalarial vaccine component. Their identification (through 1H-NMR and Aotus monkey immunization) and proper modification contributes to a logical and rational methodology for long-lasting and protective immunological memory.


Asunto(s)
Cadenas HLA-DRB1/química , Cadenas HLA-DRB1/inmunología , Vacunas contra la Malaria/química , Vacunas contra la Malaria/inmunología , Péptidos/química , Péptidos/inmunología , Animales , Aotidae , Sitios de Unión , Péptidos/síntesis química
12.
Mol Cell Biochem ; 430(1-2): 149-160, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28205097

RESUMEN

This study was aimed at characterising the PPE7 protein from the PE/PPE protein family. The presence and transcription of the rv0354c gene in the Mycobacterium tuberculosis complex was determined and the subcellular localisation of the PPE7 protein on mycobacterial membrane was confirmed by immunoelectron microscope. Two peptides were identified as having high binding activity (HABPs) and were tested in vitro regarding the invasion of Mycobacterium tuberculosis H37Rv. HABP 39224 inhibited invasion in A549 epithelial cells and U937 macrophages by more than 50%, whilst HABP 39225 inhibited invasion by 40% in U937 cells. HABP 39224, located in the protein's C-terminal region, has a completely conserved amino acid sequence in M. tuberculosis complex species and could be selected as a base peptide when designing a subunit-based, anti-tuberculosis vaccine.


Asunto(s)
Proteínas Bacterianas , Membrana Celular , Mycobacterium tuberculosis , Células A549 , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Membrana Celular/genética , Membrana Celular/metabolismo , Membrana Celular/patología , Humanos , Mycobacterium tuberculosis/genética , Mycobacterium tuberculosis/metabolismo , Mycobacterium tuberculosis/patogenicidad , Mycobacterium tuberculosis/ultraestructura , Vacunas contra la Tuberculosis/genética , Vacunas contra la Tuberculosis/metabolismo , Células U937
13.
BMC Evol Biol ; 16(1): 256, 2016 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-27894257

RESUMEN

BACKGROUND: The merozoite surface protein 7 (MSP7) is a Plasmodium protein which is involved in parasite invasion; the gene encoding it belongs to a multigene family. It has been proposed that MSP7 paralogues seem to be functionally redundant; however, recent experiments have suggested that they could have different roles. RESULTS: The msp7 multigene family has been described in newly available Plasmodium genomes; phylogenetic relationships were established in 12 species by using different molecular evolutionary approaches for assessing functional divergence amongst MSP7 members. Gene expansion and contraction rule msp7 family evolution; however, some members could have had concerted evolution. Molecular evolutionary analysis showed that relaxed and/or intensified selection modulated Plasmodium msp7 paralogous evolution. Furthermore, episodic diversifying selection and changes in evolutionary rates suggested that some paralogous proteins have diverged functionally. CONCLUSIONS: Even though msp7 has mainly evolved in line with a birth-and-death evolutionary model, gene conversion has taken place between some paralogous genes allowing them to maintain their functional redundancy. On the other hand, the evolutionary rate of some MSP7 paralogs has become altered, as well as undergoing relaxed or intensified (positive) selection, suggesting functional divergence. This could mean that some MSP7s can form different parasite protein complexes and/or recognise different host receptors during parasite invasion. These results highlight the importance of this gene family in the Plasmodium genus.


Asunto(s)
Evolución Molecular , Proteínas de la Membrana/genética , Plasmodium/genética , Proteínas Protozoarias/genética , Animales , Conversión Génica , Merozoítos/metabolismo , Familia de Multigenes , Filogenia , Plasmodium/clasificación , Plasmodium/crecimiento & desarrollo , Selección Genética
14.
Curr Issues Mol Biol ; 18: 57-78, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26317369

RESUMEN

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.


Asunto(s)
Malaria Falciparum/parasitología , Péptidos/fisiología , Plasmodium falciparum/fisiología , Proteínas Protozoarias/fisiología , Eritrocitos/parasitología , Células Hep G2 , Interacciones Huésped-Parásitos , Humanos , Esporozoítos/fisiología
15.
Curr Issues Mol Biol ; 18: 11-9, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-25830771

RESUMEN

Malaria parasites have their Achilles' heel; they are vulnerable in small parts of their relevant molecules where they can be wounded and killed. These are sporozoite and merozoite protein conserved high activity binding peptides (cHABPs), playing a critical role in binding to and invasion of host cells (hepatocytes and erythrocytes, respectively). cHABPs can be modified by specific amino acid replacement, according to previously published physicochemical rules, to produce analogues (mHABPs) having left-handed polyproline II (PPIIL)-like structures which can modulate an immune response due to fitting perfectly into the HLA-DRß1* peptide binding region (PBR) and having an appropriate presentation to the T-cell receptor (TCR).


Asunto(s)
Malaria Falciparum/parasitología , Plasmodium falciparum/fisiología , Secuencia de Aminoácidos , Animales , Antimaláricos/farmacología , Interacciones Huésped-Parásitos , Humanos , Malaria Falciparum/prevención & control , Proteínas Protozoarias/química , Proteínas Protozoarias/fisiología
16.
Biochem Biophys Res Commun ; 477(4): 654-660, 2016 09 02.
Artículo en Inglés | MEDLINE | ID: mdl-27363338

RESUMEN

Fully-protective, long-lasting, immunological (FPLLI) memory against Plasmodium falciparum malaria regarding immune protection-inducing protein structures (IMPIPS) vaccinated into monkeys previously challenged and re-challenged 60 days later with a lethal Aotus monkey-adapted P. falciparum strain was found to be associated with preferential high binding capacity to HLA-DRß1* allelic molecules of the major histocompatibility class II (MHC-II), rather than HLA-DRß3*, ß4*, ß5* alleles. Complete PPIIL 3D structure, a longer distance (26.5 Å ± 1.5 Å) between residues perfectly fitting into HLA-DRß1*PBR pockets 1 and 9, a gauche(-) rotamer orientation in p8 TCR-contacting polar residue and a larger volume of polar p2 residues was also found. This data, in association with previously-described p3 and p7 apolar residues having gauche(+) orientation to form a perfect MHC-II-peptide-TCR complex, determines the stereo-electronic and topochemical characteristics associated with FPLLI immunological memory.


Asunto(s)
Cadenas beta de HLA-DR/química , Cadenas beta de HLA-DR/inmunología , Malaria/inmunología , Plasmodium falciparum/inmunología , Receptores de Antígenos de Linfocitos T/química , Receptores de Antígenos de Linfocitos T/inmunología , Animales , Aotus trivirgatus , Sitios de Unión , Inmunidad Innata/inmunología , Memoria Inmunológica/inmunología , Unión Proteica , Relación Estructura-Actividad
17.
Malar J ; 15(1): 501, 2016 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-27756311

RESUMEN

BACKGROUND: Designing a vaccine against Plasmodium vivax has focused on selecting antigens involved in invasion mechanisms that must have domains with low polymorphism for avoiding allele-specific immune responses. The rhoptry neck protein 4 (RON4) forms part of the tight junction, which is essential in the invasion of hepatocytes and/or erythrocytes; however, little is known about this locus' genetic diversity. METHODS: DNA sequences from 73 Colombian clinical isolates from pvron4 gene were analysed for characterizing their genetic diversity; pvron4 haplotype number and distribution, as well as the evolutionary forces determining diversity pattern, were assessed by population genetics and molecular evolutionary approaches. RESULTS: ron4 has low genetic diversity in P. vivax at sequence level; however, a variable amount of tandem repeats at the N-terminal region leads to extensive size polymorphism. This region seems to be exposed to the immune system. The central region has a putative esterase/lipase domain which, like the protein's C-terminal fragment, is highly conserved at intra- and inter-species level. Both regions are under purifying selection. CONCLUSIONS: pvron4 is the locus having the lowest genetic diversity described to date for P. vivax. The repeat regions in the N-terminal region could be associated with immune evasion mechanisms while the central region and the C-terminal region seem to be under functional or structural constraint. Bearing such results in mind, the PvRON4 central and/or C-terminal portions represent promising candidates when designing a subunit-based vaccine as they are aimed at avoiding an allele-specific immune response, which might limit vaccine efficacy.


Asunto(s)
Variación Genética , Haplotipos , Malaria Vivax/parasitología , Plasmodium vivax/genética , Proteínas Protozoarias/genética , Adolescente , Adulto , Análisis por Conglomerados , Colombia , ADN Protozoario/química , ADN Protozoario/genética , ADN Protozoario/aislamiento & purificación , Evolución Molecular , Femenino , Humanos , Masculino , Persona de Mediana Edad , Filogenia , Análisis de Secuencia de ADN , Homología de Secuencia , Adulto Joven
18.
BMC Microbiol ; 15: 199, 2015 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-26438104

RESUMEN

BACKGROUND: Candida species are the most frequently found fungal pathogens causing nosocomial disease in a hospital setting. Such species must be correctly identified to ensure that appropriate control measures are taken and that suitable treatment is given for each species. Candida albicans is causing most fungal disease burden worldwide; the challenge lies in differentiating it from emerging atypical, minor and related species such as Candida dubliniensis and Candida africana. The purpose of this study was to compare identification based on MALDI-TOF MS to standard identification systems using a set of nosocomial isolates. METHODS: Eleven nosocomial samples were collected from 6 third-level hospitals in Bogotá, Colombia. All the samples were identified by combining MALDI-TOF MS with morphological characters, carbohydrate assimilation and molecular markers (D1/D2 and HWP1). RESULTS: The present work describes the first collection of atypical Colombian Candida clinical isolates; these were identified as Candida albicans/Candida africana by their MALDI-TOF MS profile. Phenotypical characteristics showed that they were unable to produce chlamydospores, assimilate trehalose, glucosamine, N- acetyl-glucosamine and barely grew at 42 °C, as would be expected for Candida africana. The molecular identification of the D1/D2 region of large subunit ribosomal RNA and HWP1 hyphal cell wall protein 1 sequences from these isolates was consistent with those for Candida albicans. The mass spectra obtained by MALDI-TOF MS were analysed by multi-dimensional scaling (MDS) and cluster analysis, differences being revealed between Candida albicans, Candida africana, Candida dubliniensis reference spectra and two clinical isolate groups which clustered according to the clinical setting, one of them being clearly related to C. albicans. CONCLUSION: This study highlights the importance of using MALDI-TOF MS in combination with morphology, substrate assimilation and molecular markers for characterising Candida albicans-related and atypical C. albicans species, thereby overcoming conventional identification methods. This is the first report of hospital-obtained isolates of this type in Colombia; the approach followed might be useful for gathering knowledge regarding local epidemiology which could, in turn, have an impact on clinical management. The findings highlight the complexity of distinguishing between typical and atypical Candida albicans isolates in hospitals.


Asunto(s)
Candida albicans/clasificación , Candida albicans/aislamiento & purificación , Candidiasis/diagnóstico , Candidiasis/microbiología , Técnicas de Tipificación Micológica/métodos , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Candida albicans/química , Candida albicans/genética , Colombia , Infección Hospitalaria/diagnóstico , Infección Hospitalaria/microbiología , ADN de Hongos/química , ADN de Hongos/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Femenino , Humanos , Lactante , Masculino , Persona de Mediana Edad , ARN Ribosómico/genética , Análisis de Secuencia de ADN , Centros de Atención Terciaria
19.
Malar J ; 14: 106, 2015 Mar 07.
Artículo en Inglés | MEDLINE | ID: mdl-25888962

RESUMEN

BACKGROUND: Different proteins derived from the membrane or the apical organelles become involved in malarial parasite invasion of host cells. Among these, the rhoptry neck proteins (RONs) interact with a protein component of the micronemes to enable the formation of a strong bond which is crucial for the parasite's successful invasion. The present study was aimed at identifying and characterizing the RON5 protein in Plasmodium vivax and evaluating its ability to bind to reticulocytes. METHODS: Taking the Plasmodium falciparum and Plasmodium knowlesi RON5 amino acid sequences as template, an in-silico search was made in the P. vivax genome for identifying the orthologous gene. Different molecular tools were used for experimentally ascertaining pvron5 gene presence and transcription in P. vivax VCG-1 strain schizonts. Polyclonal antibodies against PvRON5 peptides were used for evaluating protein expression (by Western blot) and sub-cellular localization (by immunofluorescence). A 33 kDa PvRON5 fragment was expressed in Escherichia coli and used for evaluating the reactivity of sera from patients infected by P. vivax. Two assays were made for determining the RON5 recombinant fragment's ability to bind to reticulocyte-enriched human umbilical cord samples. RESULTS: The pvron5 gene (3,477 bp) was transcribed in VCG-1 strain schizonts and encoded a ~133 kDa protein which was expressed in the rhoptry neck of VCG-1 strain late schizonts, together with PvRON2 and PvRON4. Polyclonal sera against PvRON5 peptides specifically detected ~85 and ~30 kDa fragments in parasite lysate, thereby suggesting proteolytic processing in this protein. Comparative analysis of VCG-1 strain PvRON5 with other P. vivax strains having different geographic localizations suggested its low polymorphism regarding other malarial antigens. A recombinant fragment of the PvRON5 protein (rPvRON5) was recognized by sera from P. vivax-infected patients and bound to red blood cells, having a marked preference for human reticulocytes. CONCLUSIONS: The pvron5 gene is transcribed in the VCG-1 strain, the encoded protein is expressed at the parasite's apical pole and might be participating in merozoite invasion of host cells, taking into account its marked binding preference for human reticulocytes.


Asunto(s)
Plasmodium vivax/genética , Proteínas Protozoarias/genética , Reticulocitos/parasitología , Humanos , Datos de Secuencia Molecular , Plasmodium vivax/crecimiento & desarrollo , Plasmodium vivax/metabolismo , Unión Proteica , Proteínas Protozoarias/química , Proteínas Protozoarias/metabolismo , Reticulocitos/metabolismo , Esquizontes/crecimiento & desarrollo , Esquizontes/metabolismo , Alineación de Secuencia , Análisis de Secuencia de ADN
20.
Crit Rev Microbiol ; 40(2): 117-45, 2014 May.
Artículo en Inglés | MEDLINE | ID: mdl-23445450

RESUMEN

Tuberculosis (TB) is an air-born, transmissible disease, having an estimated 9.4 million new TB cases worldwide in 2009. Eventual control of this disease by developing a safe and efficient new vaccine able to detain its spread will have an enormous impact on public health policy. Selecting potential antigens to be included in a multi-epitope, minimal subunit-based, chemically-synthesized vaccine containing the minimum sequences needed for blocking mycobacterial interaction with host cells is a complex task due to the multiple mechanisms involved in M. tuberculosis infection and the mycobacterium's immune evasion mechanisms. Our methodology, described here takes into account a highly robust, specific, sensitive and functional approach to the search for potential epitopes to be included in an anti-TB vaccine; it has been based on identifying short mycobacterial protein fragments using synthetic peptides having high affinity interaction with alveolar epithelial cells (A549) and monocyte-derived macrophages (U937) which are able to block the microorganism's entry to target cells in in vitro assays. This manuscript presents a review of the results obtained with some of the MTB H37Rv proteins studied to date, aimed at using these high activity binding peptides (HABPs) as platforms to be included in a minimal subunit-based, multiepitope, chemically-synthesized, antituberculosis vaccine.


Asunto(s)
Antígenos Bacterianos/inmunología , Adhesión Bacteriana/efectos de los fármacos , Proteínas Bacterianas/inmunología , Mycobacterium tuberculosis/inmunología , Vacunas contra la Tuberculosis/inmunología , Antígenos Bacterianos/química , Antígenos Bacterianos/aislamiento & purificación , Antígenos Bacterianos/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/aislamiento & purificación , Proteínas Bacterianas/metabolismo , Línea Celular , Células Epiteliales/microbiología , Humanos , Macrófagos/microbiología , Mycobacterium tuberculosis/química , Mycobacterium tuberculosis/fisiología , Vacunas contra la Tuberculosis/química , Vacunas contra la Tuberculosis/aislamiento & purificación
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