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L Ortiz-Ortiz

Publications and source records attributed to L Ortiz-Ortiz.

At least 19 recordsLinked to original sources
PubMed2000

Cloning and characterization of Entamoeba histolytica antigens recognized by human secretory IgA antibodies.

To identify the Entamoeba histolytica antigens capable of inducing secretory IgA (sIgA) responses in humans, a cDNA library from the strain HM1:IMSS was immuno-screened with saliva from patients with intestinal amebiasis or amebic liver abscess. Clones isolated with sIgA antibodies from patients with intestinal amebiasis corresponded to the known serine-rich protein isoform, a 29 kDa cysteine-rich protein and 1-alpha elongation factor. Clones corresponding to enolase, cyclophilin, ribosomal protein L23a, and an Hsp70 family protein were isolated with sIgA from a patient with amebic liver abscess. A glutamic acid-rich peptide (EhGARP) positive with sIgA from a patient with amebic liver abscess was also isolated; for EhGARP, no homologs were found in the protein databases. The antigens isolated are potentially useful in the development of an oral vaccine or new diagnostic tools for amebiasis.

Amino Acid Sequence↗
PubMed2000

Intestinal amoebiasis: delayed-type hypersensitivity response in mice.

Delayed-type hypersensitive (DTH) response was evaluated in C3H/HeJ mice intestinally infected with Entamoeba histolytica. Infected and non-infected control mice were challenged with amoebic antigen on day 5, 10, 15, 20, 25, 30, 40, 50, and 60 post-infection. Maximum footpad swelling was observed after 24 hours of the challenge. The E. histolytica-infected mice exhibited a DTH response on day 5, 15, 20, 25, 40 and 60 post-infection. However, on day 10, 30, and 50, such response was similar to that of the non-infected control mice. The mice developed an evident DTH response late in the course of infection (25 days post-infection). The infected mice did not show any alteration to their DTH response against heterologous unrelated antigen (sheep red blood cells), suggesting that cellular anergy was antigen-specific.

Animals↗
PubMed1999

Effect of zinc on Entamoeba histolytica pathogenicity.

The present study analyzes the effects of zinc on Entamoeba histolytica activity and on its pathogenicity. Metal activity was evaluated in vitro with regard to the parasite's viability, replication, and adhesion to epithelial cells and in vivo with regard to its pathogenicity. The results obtained in vitro show that zinc at 1.0 mM concentration does not affect amebic viability; however, it does decrease amebic replication and adhesion (P < 0.001). In vivo studies performed on a model of experimental liver abscess in the hamster indicate that the intraperitoneal administration of a single dose of zinc at 48 h after the intrahepatic inoculation of amebic trophozoites significantly inhibits (P < 0.001) abscess development. The results indicate that zinc alters the functionality of the ameba in vitro as reflected by a decrease in replication and adhesion and in vivo as manifested by inhibition of amebic pathogenicity.

Animals↗
PubMed1999

Experimental amebiasis: molecular weight analysis of Entamoeba histolytica antigens recognized by IgG antibodies.

The reactivity of sera from experimentally infected animal was studied from 5-60 days postinoculation to determine which of the E. histolytica antigens are recognized frequently to infection. Crude extract of E. histolytica trophozoites was used and sera were examined by immunoelectrotransference assay. It was observed that sera recognized polypeptide with 70 kDa molecular mass after 15 days postinoculation onward and later 14 to 24 polypeptide with molecular weight of 110-22 kDa were recognized. All the amebic antigens (polypeptides) could be recognized by sera till 60 days postinoculated animals. Significance of expression of different amebic polypeptides in terms of pathogenesis needs further investigations.

Animals↗
PubMed1998

Rapid screening test for tuberculosis using a 38-kDa antigen from Mycobacterium tuberculosis.

A screening test for the diagnosis of tuberculosis by immunodot (IDt) is described, using an antigen of Mycobacterium tuberculosis, namely, a 38-kDa glycoprotein which has shown great specificity in previous serologic analyses. The test was used to examine 28 sera from patients with lung tuberculosis. Of these, 85% were positive by micro-ELISA and by the IDt test herein described. Control sera from healthy subjects (n = 20) gave negative results for ELISA and for IDt, which indicates that the screening test is highly specific. The test is easy to handle and requires no equipment and is therefore particularly useful for field studies.

Antibodies, Bacterial↗
PubMed1998

Secretory immune response in patients with intestinal amoebiasis.

The secretory immune response in saliva from intestinal amoebiasis patients against antigens obtained from Entamoeba histolytica membranes was studied. Western blot analysis indicated that patient saliva contains secretory IgA antibodies against antigens with molecular masses ranging from 170 to 24 kDa, some of which were also recognized by saliva from healthy subjects. However, antigens of 170, 125, 46 and 37 kDa are recognized more frequently (> 90%) by the secretory IgA from patients with intestinal amoebiasis than by that from healthy subjects (< 10%).

Animals↗
PubMed1998

Secretory immune response to membrane antigens during Giardia lamblia infection in humans.

The secretory immune response in humans infected with Giardia lamblia was studied by using saliva samples and a membrane-rich protein fraction. The membrane fraction, studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, showed 24 antigen bands, ranging from 170 to 14 kDa. Saliva samples from giardiasis patients showed a heterogeneous response against the membrane fraction when they were assayed by immunoblotting. Among the antigens recognized by patient saliva samples, those of 170, 105, 92, 66, 32, 29, and 14 kDa stood out. These antigens were not recognized by saliva samples from healthy individuals. They may be of importance in future studies of protection from or diagnosis of G. lamblia infections.

Adolescent↗
PubMed1998

Intestinal amoebiasis: antibody-secreting cells and humoral antibodies.

Splenic plasma cell response and systemic antibody response to intestinal amoebiasis were studied in C3H/HeJ mice from 5 to 60 days post-inoculation with Entamoeba histolytica. At various time intervals specific antibody-secreting cells (ASC) in the spleen were measured in infected mice and non-infected control mice by enzyme-linked immunospot (ELISPOT) assay. Serum antibodies were measured by enzyme-linked immunosorbent assay (ELISA). The infected animals showed high IgA ASC from 30 to 50 days post-inoculation as compared to IgM and IgG ASC. However, class-specific serum antibody showed high IgG titre from 30 to 60 days post-inoculation as compared to IgM and IgA serum titres. Our results suggest that E. histolytica trophozoites can induce a plasma cell response in the spleen that is different from anti-amoebic antibody response in serum.

Animals↗
PubMed1996

Antigen association of total HEp-2 cell extract in the screening of autoimmune diseases by western blot.

Sera from patients with autoimmune diseases and healthy individuals were comparatively analyzed by Western blot, using total extract from HEp-2 cells as antigen. Bands between 14 and 20 kDa were present in 99% of patients with autoimmune diseases and symptomatic seronegative patients, in contrast to only 4% of healthy controls. No bands were detected in the remaining 96% of healthy controls. We propose these antigens as pathologically important for the diagnostic screening of patients with suspected autoimmune disease.

Autoantibodies↗
PubMed1995

Intestinal amebiasis: cyclic suppression of the immune response.

The cellular immune response was evaluated in a C3H/HeJ mouse model of intestinal amebiasis at 5-60 days postinoculation with Entamoeba histolytica. At various intervals, spleen lymphocytes were obtained from infected and noninfected control mice and cultured with concanavalin A (Con A), pokeweed mitogen (PWM), or ameba antigen. E. histolytica infection induced a cyclic depression of DNA synthesis when spleen lymphocytes were stimulated with a T-cell mitogen (Con A), a T- and B-cell (PWM) mitogen, or an ameba antigen. A similar response was observed in the determinations of interleukin-2 in the supernatants of Con A-stimulated spleen cells from infected mice. When spleen cells from E. histolytica-infected mice were stimulated with phorbol myristate acetate plus ionomycin, results indicated a signal-transduction defect. These alterations, observed at the cellular level, might facilitate invasion of the host by the parasite.

Animals↗
PubMed1995

Carbohydrate epitopes of Entamoeba histolytica cell surface glycoproteins are major targets of the human humoral response.

The antigens of Entamoeba histolytica recognized by antibodies in 11 individual sera from patients treated for amebic liver abscess were determined both by immunoprecipitation of metabolically-radiolabeled whole trophozoite proteins and by immunoblotting.Collectively, twenty-s even antigens ranging from 167 to 21 kDa were detected in immunoblots of whole trophozoite extracts; eight of these were recognized by all tested patient sera. Immunoprecipitation studies also revealed a complex amebic antigenic profile. Of a total of twenty immunoprecipitated polypeptides (from 200 to 24 kDa), seventeen were uniquely recognized by the patient sera. Eight of these seventeen antigens were immunoprecipitated by most immune sera. The cellular localization of trophozoite antigens was determined by analyzing plasma membrane and soluble cytosol fractions. Plasma membranes contained virtually as many antigenic moieties as the total trophozoite extract; in contrast, the soluble fraction was antigenically less complex. Mild periodate oxidation of plasma membrane antigens indicated that surface glycoproteins are highly immunogenic for the human host and that antibodies to their carbohydrate epitopes are a major component of the total response of most patients.

Animals↗
PubMed1994

Human secretory immunoglobulin A anti-Entamoeba histolytica antibodies inhibit adherence of amebae to MDCK cells.

The presence of secretory immunoglobulin A (IgA) anti-Entamoeba histolytica antibodies in the saliva of patients with intestinal amebiasis was demonstrated by immunoblot assay, and the capacity of these antibodies to inhibit amebic adherence to a monolayer of MDCK cells was analyzed. Inhibition was due to IgA antiamebic antibodies and in part to anti-Gal-binding-lectin antibodies, as demonstrated by absorption experiments with total amebic extract and with the fraction of Gal-binding lectin. These results emphasize the relevance of secretory IgA antibodies in the phenomenon of E. histolytica adherence to epithelial cells.

Animals↗
PubMed1994

Antibody response to Plasmodium vivax antigens in human malaria.

The present study investigated the serum antibody response to parasite antigens involved in human Plasmodium vivax malaria. Analysis was performed by protein immunoblotting of a pool of P. vivax preparations obtained from blood of patients from Tapachula, Chiapas (southeastern Mexico), and sera from local malarious patients. Patient sera recognized 19 P. vivax antigens with molecular sizes between 17 and 170 kD. The most frequently recognized antigens were proteins of 19, 31, 43, 72, 93, and 97 kD. These proteins could be useful in diagnostic methods and possibly relevant in vaccine design.

Adolescent↗
PubMed1994

Seroepidemiology of amebiasis in Mexico.

The presence of serum antibodies to Entamoeba histolytica was detected by indirect hemagglutination in a representative sample of the 32 federal entities of the Mexican Republic. This study was designed to include biologic, geographic, social, economic, and educational variables. The total percentage of positive sera was 8.41%. Seroprevalence varied with geographic zones, with the South Central, South Pacific, and Yucatan Peninsula areas showing the highest values (> or = 9%), and the North, Northeast, and Gulf of Mexico areas showing the lowest values (< or = 8.0%). Seroprevalence of anti-E. histolytica antibodies seemed to increase from the northern regions to the southern areas of Mexico. These results indicated that amebiasis is endemic in the Mexican Republic, with areas of high seroprevalence not related to climatic conditions. Exposure to infectious contact with E. histolytica occurred at all ages, with a higher frequency at school age.

Adolescent↗
PubMed1994

Antigenic characterization of Plasmodium vivax with monoclonal antibodies.

Monoclonal antibodies were produced against Plasmodium vivax obtained from patients living in southeastern Mexico, where P. vivax malaria is endemic. Nine hybridomas specific for this parasite were obtained. By an indirect immunofluorescence assay, seven antibodies were found to react with epitopes present in the cytoplasm of the infected erythrocyte and two with the parasite itself. By immunoblotting, five monoclonal antibodies reacted with a 17-kD protein band, three with an 85-kD band, and two with one of 45 kD. By immunogold electron microscopy, two antibodies that reacted with the cytoplasm of infected erythrocytes by immunofluorescence also labeled cytoplasmic clefts, and one, in addition, recognized caveola-vesicle complexes and the parasite matrix. These results demonstrate the value of monoclonal antibodies in identifying P. vivax antigens and disclosing their subcellular distribution.

Animals↗
PubMed1994

Intestinal amebiasis: histopathologic features in experimentally infected mice.

Intestinal amebiasis is still an important health problem in developing regions of the world. In order to advance our knowledge on the pathogenesis and to test the relevance of recently obtained in vitro observations, suitable in vivo experimental models of intestinal amebiasis are needed. In the past a variety of laboratory animals have been used, but the mouse, whose genetics and immunology is well known, has been seldomly used. Therefore, Entamoeba histolytica strain HM1:IMSS was directly inoculated into the cecum of C3H/HeJ mice, which were sacrificed at 5, 10, 15, 20, 25 and 30 days for histopathologic analysis. An ulcerative inflammatory disease highly reminiscent of human amebiasis was observed. Early 5 day lesions consisted of tiny erosions of the surface epithelium which evolved to deeper and more extensive destructive lesions of the cecal wall. Indeed, flask-shaped ulcers, intestinal perforations and intramural abscess formation were observed at later times. It was noticeable that, despite the lack of obvious significant tissue invasion by amebae, ulcerative disease was extensive and found virtually in all mice. These observations support the view that tissue invasion by trophozoites is not necessarily required for ulcerative disease to occur, suggesting a role for toxic factors released by amebae.

Animals↗