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M E Patarroyo

Publications and source records attributed to M E Patarroyo.

115 records · Page 7Linked to original sources
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Induction of protective immunity against experimental infection with malaria using synthetic peptides.

Synthetic peptides are potential vaccine candidates because they may be able to induce high antibody titres and specific cellular immune responses against native proteins and thus the whole invading organism. In a previous study we showed that immunization with molecules of relative molecular mass (Mr) 155,000 (155K) 83K, 55K and 35K, specific for the late schizont and merozoite stages of Plasmodium falciparum, could elicit either partial or total protection in Aotus trivirgatus monkeys experimentally infected with P. falciparum. Here we have chemically synthesized 18 peptides corresponding to different fragments of these proteins to immunize Aotus trivirgatus monkeys. Some peptides gave partial protection from challenge with P. falciparum parasites, but none provided complete protection individually. A combination of three partially protective peptides gave complete or almost complete protection, however, suggesting that this particular combination of peptides is a good candidate for a malaria vaccine.

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A GBP 130 derived peptide from Plasmodium falciparum binds to human erythrocytes and inhibits merozoite invasion in vitro.

The malarial GBP 130 protein binds weakly to intact human erythrocytes; the binding sites seem to be located in the repeat region and this region's antibodies block the merozoite invasion. A peptide from this region (residues from 701 to 720) which binds to human erythrocytes was identified. This peptide named 2220 did not bind to sialic acid; the binding site on human erythrocyte was affected by treatment with trypsin but not by chymotrypsin. The peptide was able to inhibit Plasmodium falciparum merozoite invasion of erythrocytes. The residues F701, K703, L705, T706, E713 (FYKILTNTDPNDEVERDNAD) were found to be critical for peptide binding to erythrocytes.

Amino Acid Sequence↗
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Proteolytic processing of the Cyt1Ab1 toxin produced by Bacillus thuringiensis subsp. medellin.

Bacillus thuringiensis produces d-endotoxins that require proteolytic processing to become active. The activation of the B. thuringiensis subsp. medellin 28 kDa (Cyt1Ab1) cytolytic toxin by trypsin, chymotrypsin and gut extract from Culex quinquefasciatus larvae was analyzed. The Cyt1Ab1 toxin of B. thuringiensis subsp. medellin was processed by all proteases tested to fragments between 23 and 25 kDa, while processing of the Cyt1Aa1 toxin produce fragments between 22.5 and 24.5 kDa. The Cyt1Ab1 toxin was preferentially processed at the alkaline pH of 12. The in vitro proteolytic processing of the Cyt1Ab1 toxin by C. quinquefasciatus larvae midgut extract showed a 25 kDa fragment; a similar result was observed when the activation was performed in the in vivo experiments. The solubilized Cyt1Ab1 toxin and the protease resistant cores generated by in vitro processing showed hemolytic activity but not mosquitocidal activity. Amino terminal sequence of the C. quinquefasciatus gut extract resistant fragment indicated that the cutting site was located between Lys31 and Asp32, with a sequence DDPNEKNNHNS; while for the trypsin-resistant fragment the cutting site was determined between Leu29 and Arg30, and for the chymotrypsin-resistant fragment between Arg30 and Lys31.

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Cultivation and characterization of stable Leishmania guyanensis complex axenic amastigotes derived from infected U937 cells.

The study of the differential regulation of several genes, in both Leishmania parasite life cycle forms, has been simplified by the development of in vitro axenic amastigote culture. Different reports have described extracellular amastigote production and maintenance from several Leishmania spp. A general approach to induce amastigote-like transformation includes progressive pH and temperature changes. Production of axenic amastigotes in continuous cultures using amastigotes recovered from macrophages is described in this report. Leishmania (Viannia) panamensis (M/HOM/PA/71/LS94) and Leishmania (V). guyanensis (M/HOM/BR/75/M4147) intracellular amastigotes were recovered from the human macrophage-like U937 cell line previously infected with promastigotes. The parasites were immediately adapted for growth and kept as axenic amastigotes at 34 degrees C and acidic pH. These organisms were able to infect macrophage cell lines, maintain amastigote morphologic features, and express stage-specific transcripts. The relevance of axenic amastigotes in characterizing virulence factors in American leishmaniasis is discussed.

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GGRGDSPCA peptide: a new antiscarring agent on glaucoma filtration surgery.

BACKGROUND AND OBJECTIVE: GGRGDSPCA synthetic peptide competes for integrin receptor in scar formation after glaucoma filtering surgery in a rabbit model. The purpose of this study was to evaluate the use of this peptide and compare it with mitomycin on glaucoma filtering surgery. MATERIALS AND METHODS: Posterior sclerectomy was performed in both eyes of 17 rabbits. The right eye received GGRGDSPCA (p605) at 0, 4, 8, 12, and 16 days after. Nine left eyes received saline as a control; the remaining 8 eyes received mitomycin C at 0.5 mg/mL intraoperative. Intraocular pressures and biomicroscopy were evaluated as well as bleb function. RESULTS: Intraocular pressure decreased significantly in both the peptide and mitomycin treated eyes in comparison with the saline group (P = 0.0003). Pressure was similar in both groups. The blebs showed filtrating function in a functional analysis at day 21 and 41 in the mitomycin cases as well as in the peptide group. Histologic analysis performed in both peptide and mitomycin groups showed inhibitory effect in fibrocellular and collagen organization with bleb formation. CONCLUSIONS: The p605 peptide showed to be similar to mitomycin C in controlling and improving glaucoma filtering surgery in rabbits. This alternative may potentially be useful for similar purposes in humans for the control of glaucoma and improvement of filtering surgery.

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Specific interactions of synthetic peptides derived from P. falciparum merozoite proteins with human red blood cells.

In the search for strategies which might help in the elucidation of molecular mechanisms involved in the red blood cell (RBC) invasion by P. falciparum merozoites, and with the specific aim of establishing whether synthetic peptides derived from selected parasite proteins bind to human RBCs, 26 different peptides were chemically synthesized and radiolabeled. It was found that the peptides could be grouped, according to their RBC-binding kinetics, into high, medium and low binding activity. A correlation was detected between the high binding activity of a peptide and the presence of either a KEK motif (or its variants LEK or KEL) or a NVXAA (where X is V or Y). Peptides with medium or low binding activities did not possess either of these two consensus sequences. Selective modification of amino acids within the KEK motif diminished their uptake or binding capacity. Competitive inhibition assays of labeled or unlabeled peptide demonstrated a correlation between the presence of KEK or NVXAA motifs and a high binding activity of a peptide. Invasion-inhibition studies showed a direct correlation between a peptide's binding activity and inhibitions of human RBC reinvasion. Other experiments showed that high binding activity peptides show a decreased uptake with related and nonrelated human erythrocytes.

Amino Acid Sequence↗