Epitope of dengue virus E protein detect human antibodies associated with mild disease: a potential peptide for vaccine development

ABSTRACT The antigenic potential of seven immunogenic peptides of the dengue virus was evaluated in the sera of patients with dengue confirmed by IgM/IgG serology. Antibodies IgM and IgG against dengue virus peptides were analyzed by ELISA in 31 dengue sero-positive and 20 sero-negative patients. The P5 peptide showed significant IgG immunoreactivity mostly in the sera of patients with dengue without warning signs in comparison with patients with dengue with warning signs, correlating with mild disease. This finding suggests that the low antibody response against P5 epitope could be a risk factor for higher susceptibility to dengue virus infection with warning signs, and that P5 could be a potential antigen for vaccine development.

Intestinal parasites and genotyping of Giardia duodenalis in children: first report of genotype B in isolates from human clinical samples in Mexico

Giardia duodenalis is one of the most prevalent enteroparasites in children. This parasite produces several clinical manifestations. The aim of this study was to determine the prevalence of genotypes of G. duodenalis causing infection in a region of southeastern Mexico. G. duodenalis cysts were isolated (33/429) from stool samples of children and molecular genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis, targeting the triosephosphate isomerase ( tpi ) and glutamate dehydrogenase ( gdh ) genes. The tpi gene was amplified in all of the cyst samples, either for assemblage A (27 samples) or assemblage B (6 samples). RFLP analysis classified the 27 tpi -A amplicons in assemblage A, subgenotype I. Samples classified as assemblage B were further analysed using PCR-RFLP of the gdh gene and identified as assemblage B, subgenotype III. To our knowledge, this is the first report of assemblage B of G. duodenalis in human clinical samples from Mexico.

Giardia duodenalis: analysis of secreted proteases upon trophozoite-epithelial cell interaction in vitro

Protease secretion by Giardia duodenalis trophozoites upon interaction with epithelial cells and its association with the parasite adhesion was studied in co-cultures of parasites with IEC6 epithelial cell monolayers in the presence or absence of protease inhibitors. Proteolytic activity in supernatants from trophozoites was enhanced when they were co-cultured with IEC6 cells. This activity was strongly inhibited by pre-incubation of live trophozoites with E-64 and TPCK and a concomitant inhibition of parasite adhesion to IEC6 cells was observed. These data suggest that trophozoites secrete cysteine-type proteases that play a role in the adhesion of G. duodenalis to epithelial cells.

Evaluation of albendazole prodrugs in experimental trichinellosis

Background. Two albendazole (ABZ) prodrugs, N-methoxycarbonyl-N'-[(2-nitro-4-propylthio) phenyl] thiourea (compound 2), and N-methoxycarbonyl-N'-[2-nitro-5-propylthio) phenyl] thiourea (compound 3) have recently been synthesized. These compounds showed greater solubility than ABZ itself. Methods. In order to evaluate the biotransformation of compounds 2 and 3 to ABZ and/or ABZ-sulphoxide (ABZ-SO), plasma samples taken from mice treated with the prodrugs were analyzed by HPLC. Also, the anthelmintic activity of compounds 2 and 3 against Trichinella spiralis was evaluated in mice experimentally infected with the prarasite. Results. The presence of ABZ and/or ABZ-SO was demostrated in plasma samples taken at different time intervals after prodrug administration, although their levels were low compared to those reached in mice treated with ABZ. Additionally, prodrugs 2 and 3 were also detected in these samples. In regrad to the anthelmintic activity of ABZ prodrugs, it was shown that compound 3 was more active than compound 2. Additionally, it was as effective as ABZ against T. spiralis pre-adult, adult, and female fecundity. However, compound 3 was not as active sa ABZ against the muscle stage of the parasite. Conclusions. Compound 3 had better anthelmintic activity againts T. spiralis than compound 2. The bioconversion of compounds 2 and 3 to ABZ and/or ABZ-SO was demostrated by HPLC, but they did not reach equivalant concentrarion to that of ABZ. Prodrugs 2 and 3 were also present in plasma samples, suggesting that prodrugs were not efficiently reduced in the intestine of mice

Selorogic evidences suggesting the presence of borrelia burgdorferi infection in Mexico

Background. Lyme disease is the most common vector-borne Human disease in Europe and the United States. In Mexico, clinical cases suggestive of lyme borreliosis have been reported; however, infection was not confirmed by serologic or microbiologic tests. Methods. To study the prevalence of IgG antibodies againts Borrelia burgdorferi among Mexican persons, a community-based sero-survery including all states of Mexico was done. A sample of 2,890 sera representing individuals of all ages and all socioeconomic levels was studied. Antibodies ati-B. burgdorferi were determined by enzyme-linked immunosorbent assay (ELISA) using a whole-cell sonicated extract of B. burgdorferi strain B31. Serum specimens positive for ELISA were further studied by Western blot (WB). A serum sample was considered positive by WB if at least three of the following protein bands were recognized: 18, 24, 28, 31, 34, 39, 41, 45, 58, 62, 66, and 93 KDa. Some WB positive specimens were futher confirmed with an inmmunodot-blot (IDB) test using recombinant and purified B. burgdorferi proteins. Results. Of the 2,890 specimens, 34 were positive for ELISA; nine of these 34 were confirmed as positive by WB. Four of the nine WB positive sera were testd by IDB and all four were positive. The prevalence of WB confirmed cases in the sample studied was 0.3 percent. Positive specimens were from residents of the northeastern and central areas of Mexico. Conclusions. the resological evidences of this study suggest that Borrelia burgdorferi infection is present in the Mexican population. This finding should be confirmed by documenting the infection in clinical cases and in tick vectors

Comparación de dos tinciones en la detección de Pneumocystis carinii / Comparison of two staining methods in the detection of pneumocystis carinii

Evaluar dos metodologías para identificar P. carinii en lavado bronquio-alveolar. Material y métodos. Se obtuvo lavado bronquio-alveolar de 20 ratas a las que se indujo una infección de P. carinii por inmunosupresión. Las muestras se tiñieron con tres métodos: azul de toluidina modificada (ATM), Diff Quik (DQ), y tinción de plata como estándar de oro. Dos observadores hicieron la búsqueda de P. carinii en forma independiente. Resultados. La tinción de plata mostró P. carinii en 15 de las 20 muestras. Con DQ hubo una especificidad de 100 por ciento pero 27 por ciento de sensibilidad; con ATM la sensibilidad fue de 93 por ciento pero especificidad de 80 por ciento. La concordancia interobservadores (índice kappa) fue de 0.11 con DQ y de 0.53 con ATM. Conclusión. Nuestros resultados sugieren la conveniencia de usar la tinción de plata para garantizar los resultados en el diagnóstico de neumonía por P carinii

Frecuencia de anticuerpos séricos contra Pneumocystis carinii en un grupo de mujeres embarazadas sanas y sus productos / Frequency of serum antibodies againts Pneumocystis carinii in a group of health pregnant women and their infants

Para determinar la frecuencia con la que se encuentran anticuerpos contra Pneumocystis carinii en un grupo de 58 mujeres embarazadas sanas, y la frecuencia con la que transfieren estos anticuerpos al producto, se utilizaron muestras de suero tomadas de la madre al momento del parto y del cordón umbilical para búsqueda de anticuerpos por la técnica de Western blot (inmunotransferencia). Se utilizó como fuente de antígeno P. carinii derivado de rata inmunosuprimida. En 28 (48 por ciento) sueros se identificó la presencia de anticuerpos contra P. carinii; existió prueba de transferencia en 21 (75 por ciento) de las muestras tomadas del cordón umbilical. El antígeno más reconocido estuvo entre 45-55 kDa. En 20 por ciento de las muestras maternas, se encontró reconocimiento al antígeno de 95 kDa, a diferencia de las muestras tomadas del cordón umbilical, en las cuales no se identificó respuesta contra este antígeno, que suponemos puede der detectado en la primoinfección natural

Historia natural de la infección amibiana durante el primer año de vida: estudio comparativo de cohortes / Natural history of amebic infection in infants: a cohort comparative study

Introducción. El mecanismo de transmisión intrafamiliar es uno de los más importantes en la infección amibiana; sin embargo el papel de la madre portadora no ha sido demostrado con objetividad y existe escasa información sobre la historia natural de la respuesta inmune humoral en los portadores asintomáticos. Fue objetivo de este estudio identificar el papel de la infección materna por Entamoeba hystolytica en la transmisión del parásito a sus hijos y su relación con la respuesta inmune humoral así como con la caracterización del tipo de zimodemo. Material y métodos. Se efectuó un estudio comparativo y prolectivo de cohortes madre-recién nacido caracterizado por la presencia (n= 21) o ausencia (n= 29) de madres portadoras del parásito, a las cuales se visitó cada 2 semanas durante un año, a partir del nacimiento de los hijos. En cada ocasión se obtuvieron muestras de heces del binomio para la identificación de E. histolytica por estudios coproparasitoscópicos y cultivo de Robinson. Cada 4 meses se colectó sangre venosa del binomio para hemaglutinación indirecta y Western-blot. Resultados. El 51 por ciento de las muestras fecales de las madres portadoras mantuvieron esta característica a lo largo del seguimiento, mientras que sólo en el 1.5 por ciento de las muestras de las madres no portadoras se idenificó al parásito P < 0.0001). La incidencia de infección amibiana durante el primer año de vida de los hijos índice fue de 10 por ciento (5/50), cuatro pertenecientes a la cohorte de madres portadoras y uno a la de no portadoras (P = 0.1). En los cinco niños infectados los títulos de anticuerpos antiamibianos fueron más altos que el resto de los hijos (P < 0.02) y el Western blot mostró que hay fracciones antigénicas que inducen anticuerpos séricos de clase IgG, IgA e IgM contra este parásito desde fases muy tempranas. Conclusiones. ninguno de los portadores, incluidos los cinco niños infectados, presento manifestaciones de enfermedad amibiana. El patrón de excreción de quistes de E. histolytica entre las madres fue diferente, a pesar de compartir las mismas características del medio ambiente. La respuesta inmunológica observada en los niños infectados, sugiere mecanismos de inducción de anticuerpos diferentes a los descritos para la amibiasis intestinal invasora

Utrastructural localization of Giardia lamblia antigens by human IgA and IgG

Surface and intracellular antigenic components of Giardia lamblia trophozoites were investigated using anti-giardia IgA and IgG antibodies from human milk and serum. Immunoperoxidase techniques were employed to identify these components with light and electron microscopy. Cryosections of trophozoites of G. lamblia were used with the purpose of allowing direct exposure of intracellular components in the light microscopy studies. Fixed trophozoites of this parasite were used for ultraestructural studies. The antigenic components that were linked with anti-Giardia IgA and IgG antibodies were located diffusely on the full extent of the parasite surface, mainly on the dorsal area. In the frozen section immunostaining was also found in the cytoplasm. Flagella and ventral surface were also immunoperoxidase positive. It is concluded that surface and intracellular antigens of G. lamblia trophozoites induce a human immune humoral response