Antibodies to the alkaline phosphatase (AP) of Schistosoma mansoni in infected human and mice ser... more Antibodies to the alkaline phosphatase (AP) of Schistosoma mansoni in infected human and mice sera were evaluated by a direct solid-phase AP immunoadsorption assay (APIA) and by Western blot and immunostaining. APIA consisted of (a) solid-phase capture of immunoglobulins from infected human or mice, (b) immunoadsorption of the enzyme antigen by the antibodies, and (c) detection of the enzymatic activity. By this procedure the appearance of the anti-AP response in mice was detected around 50 days post-infection; this response was not specific for an AP of a given schistosome strain and it was not induced by an autoimmunity phenomenon. Fourteen out of 15 sera from infected people tested by APIA showed a clear antibody response against this enzyme. Immunoblots in non-reducing conditions supported APIA results indicating that the parasite AP was specifically recognized by the antibodies present in infected human and mice sera. These results suggest the possible usefulness of the schistosome AP as a marker for S. mansoni infection.
We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study... more We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study was to evaluate the extent and the dynamic of HIV-1 dissemination in eight Warao communities. HIV-1 infection was evaluated in 576 Warao Amerindians from the Orinoco Delta. Partial HIV-1 pol sequences were analyzed to reconstruct the spatiotemporal and demographic dynamics of the epidemic. HIV-1 antibodies were present in 9.55% of Warao Amerindians, ranging from 0 to 22%. A significantly higher prevalence was found in men (15.6%) compared with women (2.6%), reaching up to 35% in men from one community. All but one isolates were classified as subtype B. Warao's HIV-1 subtype-B epidemic resulted from a single viral introduction at around the early 2000s. After an initial phase of slow growth, the subtype B started to spread at a fast rate (0.8/year) following two major routes of migration within the communities. A dramatic high prevalence was documented in almost all the communities of Warao Amerindians from the Orinoco Delta tested for HIV-1 infection. This epidemic resulted from the dissemination of a single HIV-1 subtype B founder strain introduced about 10 years ago and its size is probably doubling every year, creating a situation that can be devastating for this vulnerable Amerindian group.
Occult hepatitis B infection (OBI) is characterized by the presence of hepatitis B virus (HBV) DN... more Occult hepatitis B infection (OBI) is characterized by the presence of hepatitis B virus (HBV) DNA in the absence of HBsAg in the serum of patients. The aim of this study was to characterize HBV infection among a Piaroa community, an Amerindian group which exhibits significant evidence of exposure to HBV but relatively low presence of HBsAg, and to explore the presence of OBI in this population. Of 150 sera, with 17% anti-HBc and 1.3% HBsAg prevalence, 70 were tested for the presence of HBV DNA. From these, 25 (36%) were found positive for HBV DNA by PCR in the core region. Two of these 25 sera were HBsAg positive, indicating an overt infection. Of the remaining 68 sera tested, 23 exhibited OBI. Of these, 13 were HBV DNA out of 25 anti-HBc positive (52%) and 10 HBV DNA positive, out of 43 anti-HBc negative (23%), with a statistical significance of p = 0.03. Viral DNA and HBsAg were present intermittently in follow up sera of 13 individuals. Sequence analysis in the core region of the amplified DNA products showed that all the strains belonged to HBV genotype F3. The OBI isolates displayed 96-100% nucleotide identity between them. One isolate exhibited the co-circulation of a wild type variant with a variant with a premature stop codon at the core protein, and a variant exhibiting a deletion of 28 amino acids. The frequency of OBI found in this Amerindian group warrants further studies in other communities exhibiting different degrees of HBV exposure.
Lectins from Lens culinaris and Arachis hypogaea immobilized on polyacrylamide beads were used fo... more Lectins from Lens culinaris and Arachis hypogaea immobilized on polyacrylamide beads were used for selective isolation of glycosylated surface membrane domains of adult Schistosoma mansoni worms, and the method was compared with the membrane isolation procedure developed with polycationic (Affi-Gel) beads. The lentil lectin proved to be suitable for interaction with surface membrane components: an increment in the specific activities of tegumental phosphohydrolases was observed in the bound fraction with respect to that observed in a total worm homogenate. A characteristic polypeptide pattern on gel electrophoresis was also seen, more restricted than that obtained with the bound Affi-Gel fraction. Immobilized peanut lectin was not successful as a method for isolating membrane material from the tegument of adult worms. Solubilization and dissociation of the lentil lectin-bound enzyme markers was achieved after addition of detergent and competing sugars. Glycosylation of the solubilized enzymes was further confirmed by affinity chromatography with fresh lentil lectin-coated beads. These results, together with histochemical evidences, suggest that the active sites of some of these enzymes are located within or close to the cytoplasmic leaflet of the surface tegumental membranes, and allow us to propose a model for the double surface membrane complex where some proteins may be crossing the two bilayers.
G.E.N.: organo oficial de la Sociedad Venezolana de Gastroenterología, Endocrinología y Nutrición
In the study we show the usefulness of PCR (polymerase chain reaction) to follow patients with ch... more In the study we show the usefulness of PCR (polymerase chain reaction) to follow patients with chronic hepatitis, infected with hepatitis C virus (HCV) of Centro Médico de Caracas. The study included 14 patients: 12 anti-HCV positive, 1 with chronic autoimmune hepatitis and 1 classified as non B-non C hepatitis. The patients were divided in 3 groups: Group 1 (5 pretreatment patients, anti-HCV+), 4 with increase in ALT and PCR positive, 1 with normal ALT and PCR negative. Group 2 (7 treated with recombinant interferon alpha 2b), 4 without normalization of ALT and PCR positive, 3 with normalization of ALT and PCR negative. Group 3 (control) 2 patients anti-HCV negative and PCR negative. Two posttreatment patients could be genotyped: one patient was infected with 1a and showed an early relapse with treatment and the other was infected with genotype 1b, which is reported to be more refractory to antiviral treatment. the results show a 100% correlation between biochemical markers of HCV infected patients and the presence of viral RNA detected by PCR. the usefulness of determination of genotype to assess any prognostic value of this parameter in Venezuela is discussed.
Alrededor de 3 millones de personas están infectadas con el virus de inmunodeficiencia humana (VI... more Alrededor de 3 millones de personas están infectadas con el virus de inmunodeficiencia humana (VIH) en las Américas y unas 110000 en Venezuela, donde la distribución de subtipos es bastante homogénea, representada principalmente por el subtipo B y una escasa representación de subtipos no B y/o formas recombinantes. El predominio del subtipo B en las Américas quizá se deba al efecto fundador de esta variante viral en los años 1960-1970, siendo Haití uno de los países donde pudo haberse iniciado la epidemia para luego diseminarse hacia otros países. El incremento en la frecuencia de subtipos no B en las Américas ha sido asociado a varios comportamientos de riesgo: el uso de drogas endovenosas, el comercio sexual y movilizaciones sanitarias o militares. En países como Cuba, Brasil y en países del Cono Sur la presencia de subtipos no B y de formas recombinantes es mayor que en el resto de la región. Esta situación pudiera ser el espejo de lo que encontremos en todo el continente america...
Antibodies to the alkaline phosphatase (AP) of Schistosoma mansoni in infected human and mice ser... more Antibodies to the alkaline phosphatase (AP) of Schistosoma mansoni in infected human and mice sera were evaluated by a direct solid-phase AP immunoadsorption assay (APIA) and by Western blot and immunostaining. APIA consisted of (a) solid-phase capture of immunoglobulins from infected human or mice, (b) immunoadsorption of the enzyme antigen by the antibodies, and (c) detection of the enzymatic activity. By this procedure the appearance of the anti-AP response in mice was detected around 50 days post-infection; this response was not specific for an AP of a given schistosome strain and it was not induced by an autoimmunity phenomenon. Fourteen out of 15 sera from infected people tested by APIA showed a clear antibody response against this enzyme. Immunoblots in non-reducing conditions supported APIA results indicating that the parasite AP was specifically recognized by the antibodies present in infected human and mice sera. These results suggest the possible usefulness of the schistosome AP as a marker for S. mansoni infection.
We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study... more We previously reported HIV-1 infection in Warao Amerindians from Venezuela. The aim of this study was to evaluate the extent and the dynamic of HIV-1 dissemination in eight Warao communities. HIV-1 infection was evaluated in 576 Warao Amerindians from the Orinoco Delta. Partial HIV-1 pol sequences were analyzed to reconstruct the spatiotemporal and demographic dynamics of the epidemic. HIV-1 antibodies were present in 9.55% of Warao Amerindians, ranging from 0 to 22%. A significantly higher prevalence was found in men (15.6%) compared with women (2.6%), reaching up to 35% in men from one community. All but one isolates were classified as subtype B. Warao's HIV-1 subtype-B epidemic resulted from a single viral introduction at around the early 2000s. After an initial phase of slow growth, the subtype B started to spread at a fast rate (0.8/year) following two major routes of migration within the communities. A dramatic high prevalence was documented in almost all the communities of Warao Amerindians from the Orinoco Delta tested for HIV-1 infection. This epidemic resulted from the dissemination of a single HIV-1 subtype B founder strain introduced about 10 years ago and its size is probably doubling every year, creating a situation that can be devastating for this vulnerable Amerindian group.
Occult hepatitis B infection (OBI) is characterized by the presence of hepatitis B virus (HBV) DN... more Occult hepatitis B infection (OBI) is characterized by the presence of hepatitis B virus (HBV) DNA in the absence of HBsAg in the serum of patients. The aim of this study was to characterize HBV infection among a Piaroa community, an Amerindian group which exhibits significant evidence of exposure to HBV but relatively low presence of HBsAg, and to explore the presence of OBI in this population. Of 150 sera, with 17% anti-HBc and 1.3% HBsAg prevalence, 70 were tested for the presence of HBV DNA. From these, 25 (36%) were found positive for HBV DNA by PCR in the core region. Two of these 25 sera were HBsAg positive, indicating an overt infection. Of the remaining 68 sera tested, 23 exhibited OBI. Of these, 13 were HBV DNA out of 25 anti-HBc positive (52%) and 10 HBV DNA positive, out of 43 anti-HBc negative (23%), with a statistical significance of p = 0.03. Viral DNA and HBsAg were present intermittently in follow up sera of 13 individuals. Sequence analysis in the core region of the amplified DNA products showed that all the strains belonged to HBV genotype F3. The OBI isolates displayed 96-100% nucleotide identity between them. One isolate exhibited the co-circulation of a wild type variant with a variant with a premature stop codon at the core protein, and a variant exhibiting a deletion of 28 amino acids. The frequency of OBI found in this Amerindian group warrants further studies in other communities exhibiting different degrees of HBV exposure.
Lectins from Lens culinaris and Arachis hypogaea immobilized on polyacrylamide beads were used fo... more Lectins from Lens culinaris and Arachis hypogaea immobilized on polyacrylamide beads were used for selective isolation of glycosylated surface membrane domains of adult Schistosoma mansoni worms, and the method was compared with the membrane isolation procedure developed with polycationic (Affi-Gel) beads. The lentil lectin proved to be suitable for interaction with surface membrane components: an increment in the specific activities of tegumental phosphohydrolases was observed in the bound fraction with respect to that observed in a total worm homogenate. A characteristic polypeptide pattern on gel electrophoresis was also seen, more restricted than that obtained with the bound Affi-Gel fraction. Immobilized peanut lectin was not successful as a method for isolating membrane material from the tegument of adult worms. Solubilization and dissociation of the lentil lectin-bound enzyme markers was achieved after addition of detergent and competing sugars. Glycosylation of the solubilized enzymes was further confirmed by affinity chromatography with fresh lentil lectin-coated beads. These results, together with histochemical evidences, suggest that the active sites of some of these enzymes are located within or close to the cytoplasmic leaflet of the surface tegumental membranes, and allow us to propose a model for the double surface membrane complex where some proteins may be crossing the two bilayers.
G.E.N.: organo oficial de la Sociedad Venezolana de Gastroenterología, Endocrinología y Nutrición
In the study we show the usefulness of PCR (polymerase chain reaction) to follow patients with ch... more In the study we show the usefulness of PCR (polymerase chain reaction) to follow patients with chronic hepatitis, infected with hepatitis C virus (HCV) of Centro Médico de Caracas. The study included 14 patients: 12 anti-HCV positive, 1 with chronic autoimmune hepatitis and 1 classified as non B-non C hepatitis. The patients were divided in 3 groups: Group 1 (5 pretreatment patients, anti-HCV+), 4 with increase in ALT and PCR positive, 1 with normal ALT and PCR negative. Group 2 (7 treated with recombinant interferon alpha 2b), 4 without normalization of ALT and PCR positive, 3 with normalization of ALT and PCR negative. Group 3 (control) 2 patients anti-HCV negative and PCR negative. Two posttreatment patients could be genotyped: one patient was infected with 1a and showed an early relapse with treatment and the other was infected with genotype 1b, which is reported to be more refractory to antiviral treatment. the results show a 100% correlation between biochemical markers of HCV infected patients and the presence of viral RNA detected by PCR. the usefulness of determination of genotype to assess any prognostic value of this parameter in Venezuela is discussed.
Alrededor de 3 millones de personas están infectadas con el virus de inmunodeficiencia humana (VI... more Alrededor de 3 millones de personas están infectadas con el virus de inmunodeficiencia humana (VIH) en las Américas y unas 110000 en Venezuela, donde la distribución de subtipos es bastante homogénea, representada principalmente por el subtipo B y una escasa representación de subtipos no B y/o formas recombinantes. El predominio del subtipo B en las Américas quizá se deba al efecto fundador de esta variante viral en los años 1960-1970, siendo Haití uno de los países donde pudo haberse iniciado la epidemia para luego diseminarse hacia otros países. El incremento en la frecuencia de subtipos no B en las Américas ha sido asociado a varios comportamientos de riesgo: el uso de drogas endovenosas, el comercio sexual y movilizaciones sanitarias o militares. En países como Cuba, Brasil y en países del Cono Sur la presencia de subtipos no B y de formas recombinantes es mayor que en el resto de la región. Esta situación pudiera ser el espejo de lo que encontremos en todo el continente america...
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