Identificación de antígenos inmunorreactivos de Leptospira interrogans / Identification of immunoreactive antigens of Leptospira interrogans

Se estudió un lote de 28 sueros de llama (Lama gama) de la provincia de Jujuy, Argentina, a fin de identificar antígenos inmunorreactivos contra Leptospira interrogans. Se utilizaron distintas preparaciones antigénicas de la bacteria para estudiar la inmunorreactividad mediante microaglutinación (MAT), ELISA y Western inmunoblot. Un pool de sueros bovinos positivos a la MAT fue empleado como control. Todos los sueros de llama fueron negativos mediante MAT e igual resultado se observó mediante ELISA. Dos de los 28 sueros de llama y el pool de sueros bovinos positivos, al ser evaluados por Western inmunoblot, arrojaron resultados positivos y permitieron identificar proteínas inmunorreactivas. Por MALDI-TOF se logró establecer que la proteína asociada a los dos sueros de llama inmunorreactivos era una flagelina periplásmica de Leptospira interrogans serovar Lai STR, mientras que la asociada al pool de sueros bovinos positivos a Leptospira sp. se trataba de una lipoproteína de la membrana externa de Leptospira interrogans serovar Ballum, LipL21. Estas proteínas podrían ser utilizadas en el diseño de un nuevo ELISA aplicado al diagnóstico temprano de leptospirosis, ya sea en distintos tipos de ganado como así también en reservorios silvestres.

A batch of 28 llama (Lama gama) sera from Jujuy province in Argentina was studied in order to identify immune reactive antigens to Leptospira interrogans. Different antigenic preparations from the bacterium were used to study the immune reactivity by the microagglutinattion (MAT), ELISA and Western immunoblot tests. A control pool of positive bovine sera was used. All the llama sera were negative to MAT as well as to ELISA. Two of the llama sera and the positive bovine sera pool rendered positive results when evaluated by Western immunoblot, allowing the identification of immune reactive proteins. These proteins were identified by MALDI-TOF. A periplasmic flagellin of Leptospira interrogans serovar Lai STR called FlaB1 was identified from the reactive llama sera, and an external membrane lipoprotein of Leptospira interrogans serovar Ballum called LipL21 was identified from the pool of bovine positive sera. These proteins could be used in a new ELISA applied to the early diagnosis of leptospirosis in different kind of cattle or wild reservoirs.

Anticuerpos anticitoplasmas de neutrófilos y colitis ulcerosa inespecífica / Neutrophil anticytoplasmic antibodies and idiopathic ulcerative colitis

We studied tha presence of antineutrophil cytoplasmic antibodies in 16 patients with idiopathic ulcerative colitis, using an indirect immunofluorescence technique and specific ELISA for myeloperoxidase and proteinase 3. Twelve patients had an active disease and in ten, antineutrophil cytoplasmic antibodies were positive, with a predominantly perinuclear distribution and without specificity for myeloperoxidase or proteinase 3. These antiantineutrophil cytoplasmic antibodies could be serologic indicators of disease activity in patients with ulcerative colitis

Prevalence of antibodies to the repeat epitope of the circumsporozoite protein of Plasmodium vivax in San Luis Potosi, Mexico

The prevalence of antibodies against the repeat epitope of the circumsporozoite protein (cs) of the standard (PV210) and variant (PVK247) strain of Plasmodium vivax was determined by ELISA in 1170 sera from individual residents of seven localities of the Region Huasteca of San Luis Potosi, Mexico. The capture antigens were the synthetic peptides DDAAD and (ANGAGNQPG)4 that correspond to the repeats of the PV210 and PVK247 cs proteins, respectively. Of the analyzed serum samples, 34.1 percent (400/1170) were positive with one or both of these antigens. Of the sera, 18.2 percent (214/1170) reacted with the DDAADF peptide and 6.6 percent (78/1170) were positive with the variant synthetic peptide. Additionally, 9.2 percent (108/1170) of the samples reacted with both peptides. A sample of 10 percent of positive sera for the variant cs repeat (18/78) was tested with the cs repeat peptide of P. malariae/P. brasilianum (NAAG); almost all of them (16/18, 89 percent) being positive. These results confirm that the transmission of the variant strain of P. vivax is a common Phenomenon in endemic regions in Latin America, as well as in other tropical regions of the world. These findings may have implications for the development of a P. vivax vaccine since that based on the standard cs repeat only would not be universally protective

Niveles de anticuerpos anti-Gal en personas infectadas y no-infectadas por trypanosoma cruzi: probable inducción por bacterias y por el parásito / Anti-Gal antibodies levels in trypanosoma cruzi infected and non-infected persons: probable induction by bacteria and by the parasite

Se estudiaron los niveles de anticuerpos contra epítopes Gal Ó 1,3 Gal en 407 sueros humanos chagásicos (92) y no chagásicos (315), mediante la reacción de hemaglutinación con eritrocitos de conejo; con inmunoelectrotransferencia se investigó la reactividad de sueros con altos títulos de anticuerpos anti-Gal frente a antígenos de escherichia coli y serratia marcescens. Finalmente, utilizando un anticuerpo anti-Gal purificado se identificó epítopes Gal Ó 1,3 Gal en formas metacíclicas de 12 cepas altoandinas chilenas de trypanosoma cruzi. Entre los 92 sueros chagásicos, se demostró que en el 68,5 por ciento (63) de los menos chagásicos se detectó anticuerpos anti-Gal a títulos ò 1:1.600, mientras que entre los sueros no chagásicos, sólo el 15,6 por ciento (49) mostró respuesta anti-Gal a títulos similares. Estos datos sugieren que la determinación de estos anticuerpos podría contribuir a complementar el diagnóstico de la infección, especialmente cuando se establezcan títulos de corte ò 1:3.200. La inmunoelectrotransferencia mostró que sueros de personas infectadas con T. cruzi reconocen varios antígenos presentes en E. coli y S. marcescens, lo que refuerza la idea de que a lo menos en parte estas bacterias serían capaces de estimular estas respuestas. El análisis autorradiográfico utilizando anticuerpo anti-Gal purificado, mostró diferencias en la expresión de los epítopes Gal Ó 1,3 Gal en las diferentes cepas de T. cruzi. Estos resultados sugieren que los anticuerpos anti-Gal podrían tener real significado en los mecanismos de inmunidad natural y protección de la infección en chilenos infectados con T. cruzi

Tipos antigénicos de rotavirus circulantes en niños con diarrea aguda en Santiago de Chile / Antigenic types of rotavirus circulanting in children with acute diarrhea in Santiago, Chile

Protective immunity against rotavirus infection is directed against antigenic epitopes on the outer capsid proteins VP7 and VP4. The aim of this study was to characterize the VP7 and VP4 antigenic types circulating in different hospital areas of Santiago, Chile, obtained from children consulting for acute no bloody diarrhea in 5 hospitals representative of the 5 major health areas in Santiago. In addition, 256 rotavirus positive samples, obtained from children with acute diarrhea consulting in the north health area of Santiago between 1985-1987 were studied. All samples were processed for rotavirus by an ELISA and all rotavirus positive samples were selected for VP4 typing by PCR (types P1-P4). A total of 782 rotavirus positive samples were obtained of wich 618 (79 percent) were typeable for one specific VP7 type. VP7 type G1 represented 63 percent of the rotavirus positive samples and predominated in all areas evaluated throughout the entire period of observation. VP7 type G2 represented 13 percent of rotavirus samples, following G1 in predominance. G2 types decreased progressively in all areas in both study periods. G4 types were detected mainly during 1985-1987, and G3 types have so far not been detected. Preliminary analysis of VP4 types suggests that P1 types are predominant and closely associated with VP7 G1 type. These results are relevant for the adoption of appropiate preventive strategies for rotavirus infection, specifically aimed to the development of effective vaccines

Mapping of functional epitopes of Japanese encephalitis virus using monoclonal antibodies.

Epitopes involved in the important functions, hemagglutination (HA) and neutralization (NT), were mapped on Japanese encephalitis (JE) virus proteins by using monoclonal antibodies (MAbs). Fourteen MAbs raised against Nakayama-Yoken strain of JE virus characterized by hemagglutination inhibition (HI) and plaque reduction neutralization test (PRNT) were used to map the epitopes on the JE proteins by Western blot analysis in which non-reducing conditions were used for sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). With these MAbs, at least 8 functional epitopes were demonstrated comprising (i) epitopes recognized by 5 MAbs which gave strong HI but weak NT activities and were mapped on the envelope (E) 53 kDa protein; (ii) epitopes recognized by 2 MAbs which showed weak HI but strong NT activities and were mapped also on the E protein; (iii) epitopes recognized by 2 MAbs which possessed weak HI but no NT activities and were mapped on the E protein; (iv) an epitope recognized by 1 MAb which gave weak NT and no HI activities and was mapped on the nonstructural protein 5 (NS5); (v) an epitope recognized by 1 MAb which showed activities similar to (i) but was mapped on both E and NS5; (vi) an epitope recognized by 1 MAb which had high activities to both HI and NT and was mapped on E and NS5; (vii and viii) epitopes recognized by 1 MAb which also gave low HI but high NT, and strong HI as well as strong NT activities respectively, but their location could not be demonstrated by SDS-PAGE under non-reducing condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigenicity of sub-cellular components of Entamoeba histolytica.

Antigencity of the sub-cellular components of axenic Entamoeba histolytica trophozoites was studied. The cells were disrupted by means of a glass-teflon homogeniser and sub-cellular components were prepared by stepwise differential centrifugation. Four fractions were obtained, namely the 350 g, 6500 g, and 100,500 g fractions and the cell sap. Components of the sedimented fractions were examined by phase contrast and electron microscopy. The antigenicity of each fraction was studied by two different methods:-(1) By extraction with 0.5% sodium deoxycholate followed by testing against the reference sera; (2) By demonstration of the loss of immunological activity of the reference sera after absorption with fractionated components. It was found that all 4 fractions had varying antigenic activities as measured in the indirect hemagglutination (IHA), the complement fixation (CF) and the immunoelectrophoresis (IEP) tests. With the extraction technique, the following results were obtained:- The highest IHA activity was found in the cell sap, whereas this activity in other fractions clustered at lower levels. In the CF test, the activities associated with all 4 fractions were similar. In the IEP test, the highest activity was found in the cell sap and the least activity in the 100,500 g fraction. With the absorption technique, slightly different results were obtained. Whilst in the IHA and the IEP test, the results were in concordance with the extraction technique, the CF activity was slightly different, since it was highest in the cell sap and least in the 100,500 g fraction.