Leishmania mexicana is an intracellular protozoan parasite that infects macrophages and dendritic cells and causes a chronic cutaneous disease. Although many enzymatic activities have been reported in this parasite, the presence of kinases and phosphatases has been poorly studied. These enzymes control the phosphorylation and dephosphorylation of proteins. Specifically, protein tyrosine kinases phosphorylate tyrosine residues and protein tyrosine phosphatases (PTPases) dephosphorylate tyrosine residues. PTPase activities have been reported as pathogenic factors in various infectious microorganisms such as viruses, bacteria, and parasites. Also, it has been shown that the induction of one or more PTPase activities in macrophages represents an important pathogenicity factor in Leishmania. Recently, we reported a membrane-bound PTPase activity in promastigotes of Leishmania major. In the present work, we give evidence that promastigotes of L. mexicana are able to secrete a PTPase into the culture medium. Two antibodies: one monoclonal against the catalytic domains of the human placental PTPase 1B and a polyclonal rabbit anti-recombinant protein Petase7 from Trypanosoma brucei cross-reacted with a 50-kDa molecule. The anti-human PTPase 1B antibody depleted the enzymatic activity present in the conditioned medium. The pattern of sensitivity and resistance to specific PTPase and serine/threonine inhibitors showed that this enzyme is a protein tyrosine phosphatase.

Although hymenolepiasis is the commonest cestode infection of man, there are no data available on the human immune response to this parasite. Thus, in order to determine if infection induces antibodies against Hymenolepis nana antigens, sera from 52 infected children were initially studied on Ouchterlony plates and then by enzyme-linked immunosorbent assay (ELISA), using a crude antigenic extract prepared from scolex and neck regions of adult worms. In addition, sera from persons with cysticercosis, taeniasis and other parasitoses, and normal human sera, were studied. Only one serum from the Hymenolepis group showed precipitin antibodies against H. nana antigen, while several were positive by ELISA. The sensitivity of the ELISA was 84.62% and its specificity was 100%. Very high cross-reactivity rates were obtained with taeniasis (70.6%) and cysticercosis (75%) sera. These results show that Hymenolepis infection in man induces a low but detectable humoral immune response. Although not useful for diagnostic purposes, this may be relevant to the serodiagnosis of other tissue cestode infections of man, since antibodies detected in serological tests used for the diagnosis of cysticercosis, and probably hydatidosis, could be induced by H. nana instead of Taenia solium or Echinococcus larvae.

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El objetivo de esta investigación es conocer la prevalencia de infección por Fasciola hepatica, mediante examen serológico, coprológicos y epidemiológico en una muestra de niños aparentemente sanos residentes en la delegación Coyoacán de la Ciudad de México. En la búsqueda de anticuerpos anti-Fasciola hepatica, se analizaron los sueros de 331 niños de 6 a 12 años de edad mediante la prueba de hemoaglutinación indirecta (HAI). Se realizó examen coprológico de sedimentación simple en serie de tres a todos los participantes. El estudio epidemiológico incluyó 6 variables. Resultados. Cinco de los niños fueron seropositivos a F. hepatica con una seroprevalencia de 1.51%. El estudio coprológico no reportó huevos de F. hepatica. El análisis estadístico entre seropositividad y consumo de berros, alfalfa, y lechuga no resultó significativo (χ2 = 0.42, p = 0.84). Sin embargo se encontró una relación estadísticamente significativa entre los parásitos y la edad de los sujetos. Este hallazgo coincide con la edad de los seropositivos. No se encontró asociación entre seropositividad y vivienda, agua potable, drenaje, abastecimiento de agua o consumo de verduras crudas,(χ2=6.00,p = 0.11) la asociación con el origen de la familia también fue negativo (χ2= 1.85, p = 0.17). Conclusiones. Aunque la Ciudad de México no es una zona endémica, y no tiene características adecuadas para la fasciolosis es importante reconocer que la existencia de residentes de origen múltiple presenta riesgos como pudimos demostrar y es precisamente en la edad escolar la que se tiene como factor de riesgo demostrado