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1.
Arch Virol ; 151(10): 1961-72, 2006 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-16710631

RESUMEN

Human papillomaviruses (HPV) infect keratinocytes of skin and mucosa. Persistent infection can lead to the formation of benign tumors. In cases of high-risk HPV, such as HPV16 or 18, these may further progress to cancer. In order to support viral replication in suprabasal keratinocytes, the HPV E7 protein employs various strategies to keep keratinocytes in cycle and counteracts anti-proliferative signals from outside. HPV16 E7 can directly interfere with transforming growth factor-beta (TGF-beta) signalling by binding to Smad proteins mediating growth arrest. It has been speculated that this property of HPV16 E7 contributes to HPV-associated carcinogenesis. Here, we show that E7 proteins from different low- and high-risk HPV types bind to Smad 1 to 4. The E7 protein from HPV1, a low-risk HPV causing plantar warts, efficiently inhibited Smad 3-induced transcription. Our data strongly indicate that the Smad-binding capacity of E7 proteins from different HPVs may preserve keratinocyte proliferation required for the productive viral life cycle rather than promoting carcinogenesis.


Asunto(s)
Proteínas E7 de Papillomavirus/genética , Proteínas E7 de Papillomavirus/metabolismo , Proteínas Smad/metabolismo , Activación Transcripcional , Proliferación Celular , Queratinocitos/citología , Queratinocitos/virología , Papillomaviridae/química , Verrugas/virología
2.
Am J Trop Med Hyg ; 65(5): 573-82, 2001 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-11716117

RESUMEN

We present a new polymerase chain reaction assay based on telomeric sequences of Leishmania donovani. When this assay was used in dilutions of purified L. donovani DNA, a strong amplification signal was observed with 1 fg of DNA. In a specificity test that used purified DNA from Old World and New World Leishmania, the assay recognized all parasites isolated from patients with visceral leishmaniasis, except for 2 isolates of Leishmania colombiensis from Venezuela and 1 isolate from Brazil. All Leishmania major and Leishmania tropica isolates tested were negative, except for one isolate in each species. We also used the assay on fresh and archive bone marrow samples recovered from Giemsa-stained slides and from dried blood stains.


Asunto(s)
Leishmania/aislamiento & purificación , Leishmaniasis Visceral/parasitología , Reacción en Cadena de la Polimerasa/métodos , Telómero , Adulto , Animales , Secuencia de Bases , Médula Ósea/parasitología , Preescolar , Femenino , Humanos , Lactante , Leishmania/genética , Masculino , Datos de Secuencia Molecular
3.
Vaccine ; 19(4-5): 423-30, 2000 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-11027804

RESUMEN

The genes, ORFF and BT1 (previously ORFG), are part of the multigenic LD1 locus on chromosome 35 which is frequently amplified in Leishmania. BT1 encodes a biopterin transporter, while the function of the ORFF gene product is unknown, but it is localized to the nucleus. We show here that immunization of mice with recombinant ORFF and BT1 proteins, individually, or in combination, conferred partial protection against challenge with Leishmania donovani. Protection correlated with the production of antigen-specific antibodies and in vitro splenocyte proliferation. Thus, these antigens can be potential vaccine candidates against visceral leishmaniasis.


Asunto(s)
Antígenos de Protozoos/administración & dosificación , Leishmania donovani/inmunología , Leishmaniasis Visceral/prevención & control , Animales , Anticuerpos Antiprotozoarios/sangre , Modelos Animales de Enfermedad , Genes Protozoarios , Inmunización , Técnicas In Vitro , Leishmania donovani/genética , Leishmaniasis Visceral/inmunología , Activación de Linfocitos , Ratones , Ratones Endogámicos BALB C , Familia de Multigenes , Proteínas Protozoarias/genética , Proteínas Protozoarias/inmunología , Proteínas Recombinantes/administración & dosificación
4.
Mol Biochem Parasitol ; 104(1): 93-105, 1999 Oct 25.
Artículo en Inglés | MEDLINE | ID: mdl-10589984

RESUMEN

We have previously described two genes, ORFF and ORFG, from the LD1 locus near one telomere of chromosome 35, which are frequently amplified in Leishmania isolates. In Leishmania donovani LSB-51.1, gene conversion of the rRNA gene locus on chromosome 27 with these two genes resulted in their over-expression, because of their transcription by the RNA polymerase I-mediated rRNA promoter. The predicted ORFG protein has substantial sequence homology to the ESAG10 gene product from the Trypanosoma brucei VSG expression site and both are putative membrane proteins. Using successive rounds of gene replacement of the three ORFG genes in L. donovani LSB-51.1, ORFG null mutants were obtained. These mutant cell lines show a direct relationship between ORFG mRNA, protein expression levels and active transport of biopterin into the cells. Transformation of the null mutant with a plasmid containing ORFG restores biopterin transport activity. In addition, the null mutants are unable to grow in the absence of supplemental biopterin. Thus, ORFG encodes a biopterin transporter and has been renamed BTI.


Asunto(s)
Biopterinas/metabolismo , Proteínas Portadoras/metabolismo , Genes Protozoarios , Leishmania donovani/genética , Proteínas Protozoarias/metabolismo , Animales , Transporte Biológico , Línea Celular , Mutación , Sistemas de Lectura Abierta , Proteínas Recombinantes/biosíntesis
5.
Am J Trop Med Hyg ; 61(3): 482-7, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10497995

RESUMEN

The serodiagnostic potential of recombinant ORFF protein (rORFF) from Leishmania infantum was assessed by ELISA. Of 49 sera from confirmed cases of visceral leishmaniasis (VL), all were seropositive using 5 ng of rORFF and serum diluted 1:20, while only 38 were positive with 500 ng of soluble antigen (SA) and 44 were positive by a direct agglutination test. There was also a positive correlation between spleen size and level of seropositivity with rORFF or SA. The reciprocal endpoint titer with rORFF was 1,280 for sera from VL patients, but < 20 with sera from malaria, filariasis, and tuberculosis patients, as well as with sera from healthy individuals from endemic and non-endemic areas. Sera from 10 confirmed cutaneous leishmaniasis cases from Turkey were negative or only weakly positive with rORFF although 9 were positive with SA. Thus, rORFF protein appears useful as a sensitive reagent for the differential diagnosis of VL caused by the Leishmania donovani complex.


Asunto(s)
Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos , Leishmania donovani/inmunología , Leishmaniasis Visceral/diagnóstico , Animales , Antígenos de Protozoos/genética , Antígenos de Protozoos/inmunología , Niño , Diagnóstico Diferencial , Ensayo de Inmunoadsorción Enzimática/métodos , Femenino , Humanos , Leishmaniasis Visceral/parasitología , Masculino , Proteínas Recombinantes/inmunología , Sensibilidad y Especificidad , Bazo/patología
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