Cholera toxin: A paradigm of a multifunctional protein.

Cholera toxin (CT) was discovered exactly half a century ago by S.N. De. We have come a long way since this epoch-making discovery. Retrospectively, science had to wait a long time since Koch’s prediction of the existence of a toxin, and its actual discovery by De. CT is not just another enterotoxin that causes the signs and symptoms of the dreaded disease, cholera. It is unique in many respects, starting from its structure to its functions. CT is a multifunctional protein that is capable of influencing the immune system in many ways. It not only has remarkable adjuvant properties, but also acts as an anti-inflammatory agent, by modulating specific signal transduction pathways. Its immunomodulatory properties can be harnessed for treatment of various autoimmune disorders, and have shown great promise in the area of immunotherapeutics. CT can truly be considered as a paradigm of a multifunctional protein.

Helicobacter pylori vaccine: mucosal adjuvant & delivery systems.

Vaccination, especially mucosal vaccination, is considered to be effective in the management of Helicobacter pylori infections. However, most antigens alone cannot induce immune responses when administered mucosally and need to be co-administered with adjuvants or delivery systems. The current research on the mucosal adjuvant and delivery systems of vaccine against H. pylori, including advantages and disadvantages, mechanisms and applications is discussed in this review. Mutants of cholera toxin (CT) and the heat labile enterotoxin of Escherichia coli (LT), CpG oligodeoxynucleotides, biocompatible and biodegradable polymers, and live attenuated bacterial vectors may be promising adjuvant and delivery systems for H. pylori vaccine.

Intranasal sensitization with Blomia Tropicalis antigens induces allergic responses in mice characterized by elevated antigen-specific and non-specific serum ige and peripheral blood eosinophil counts

Para avaliar a capacidade alergizante do antígeno da Blomia tropicalis (Bt) a produção de IgE específica e não específica a antígeno Bt foi monitorada em camundongos BALB/c após exposição ao antígeno por via nasal. Foi evidenciado que Bt contem um alérgeno funcional em seus componentes. Os componentes alergênicos entretanto, quando administrados por via intra-nasal, sem qualquer adjuvante, não induzem resposta IgE durante um pequeno período. Por outro lado, a inoculação intra-nasal de antígenos Bt aumentou a resposta sérica de IgE em camundongos pré-tratados por uma injeção inicial sensibilizante sub-cutânea aos mesmos antígenos. A inoculação do antígeno Bt sem as injeções sensibilizantes iniciais induziu a produção de anticorpos IgE somente quando o antígeno foi administrado de maneira contínua, por um período longo de mais de 24 semanas. Mesmo quando as injeções sensibilizantes iniciais foram ausentes, o antígeno Bt inoculado com a toxina de cólera (CT) como adjuvante mucoso também aumentou de maneira significante a resposta IgE antígeno específica do Bt dependendo da dose de CT administrada conjuntamente. O presente estudo também demonstrou que camundongos inoculados com antígeno Bt/CT mostram aumento do nível IgE não específico no soro e médias de eosinófilos no sangue periférico sem qualquer elevação da contagem total de leucócitos. A análise por Immunoblot demonstrou cinco principais componentes antigênicos reativos aos anticorpos IgE induzidos. Estes componentes na posição 44-64 kilodaltons foram considerados importantes antígenos-candidatos para o diagnóstico da alergia relacionada ao ácaro.

Utilización de placas de elisa de alta y de baja avidez en la determinación de anticuerpos contra la toxina de cólera / The use of low and high binding elisa plates in the determination of cholera antitoxin antibodies

Los sueros de estudio de inmunogenicidad de una vacuna oral de células enteras de Vibrio cholerae 01 más la subunidad B recombinante de la toxina (CE/sBr) fueron procesados para la determinación de anticuerpos antitoxina de cólera en placas de elisa de alta y de baja avidez. Los títulos de anticuerpos antitoxina, de la clase IgG, de los sueros prevacunales estuvieron incrementados de 5 a 7 veces, en las placas de alta avidez, comparados con los títulos obtenidos en las placas de baja avidez. Igualmente, los títulos de los sueros post vacunales fueron 3 veces superiores cuando se realizó la misma comparación de placas. Por consiguiente, la tasa de seroconversión medida en las placas de baja avidez fue de 39 por ciento, comparada con el 68 por ciento al utilizar las placas de baja avidez. El suero control de alto título de anticuerpos no detectó el problema. Se sugiere utilizar placas de baja avidez al determinar anticuerpos contra la toxina de cólera por la técnica de elisa

La inmunología del cólera y la biología molecular de la toxina colérica: progresos recientes y perspectivas futuras / The immunology of the cholera and th molecular biology of toxins

Recientemente Vibrio cholerae ha llamado mucho la atención de los investigadores por ser un inmunógeno muy potente y, al mismo tiempo, un coadyuvante inmunomodulador de la respuesta inmunitaria en la mucosa intestinal, tanto para los antígenos que se administran mezclados como los ligados covalentemente a la toxina colérica. La inmunopatogenia del cólera es un fenómeno complejo. En este artículo se comunican los resultados preliminares de experimentos realizados con ratas de laboratorio para conocer la respuesta intestinal de la IgA en los roedores y los humanos

La inmunología del cólera y la biología molecular de la toxina colérica / The cholera immunology and the molecular biology of the toxin cholera

La toxina colérica (TC) y su análoga enteroxina termolábil (TL) de la Escherichia coli tienen varios efectos inmunomodulares, que podría explicar su acción adyuvante para estimular la síntesis de la IhA secretora, después de la inmunización bucal. En un modelo murino experimental esos efectos incluyen: la presentación más eficiente de los antígenos por los macrófagos y otras células B con una síntesis incrementada de IgA y otros efectos importantes sobre la proliferación de los linfoscitos T y su producción de linfocinas (interleucinas). La capacidad coadyuvante se debe a que la TC tiene una acción ribolisante de ADP, que lleva a un incremento del AMP cíclico en la célula afectada y por ello pudiera ser difícil de eliminar la enterotoxicidad, sin pérdida de su capacidad adyucante; sin embargo, se ha demostrado que la TC y la subunidad atóxica B (TCB) tienen la propiedad de facilitar la respuesta inmunitaria de la mucosa ante la presencia de varios epitopos o antígenos adyuvantes que pudieran servir como vehículo para inducir una respuesta específica de IgA secretora, ante un límite muy amplio de antígenos para la vacunación humana contra el cólera y otras infecciones entéricas

Oral vaccine against cholera prepared from Vibrio cholerae antigen(s).

Albino rats aged 7-8 weeks old purchased from the National Laboratory Animal Centre, Salaya, Nakhon Pathom, were found to be a good animal model for the study on immunogenicity of V. cholerae antigens. Seventy-two rats were fasted for 15 hours before feeding each one with 1 ml of 5% NaHCO3 to reduce gastric acidity prior to immunization. They were divided into 9 groups of 8 rats and immunized orally with 2 ml, each, of the V. cholerae antigens dissolved or suspended in Cassamino acid as follows: group 1 (control): Cassamino acid (Ca) alone; group 2 (control): 2.5% formalinized sheep red blood cells (F-SRBC); group 3: 1,000 micrograms of lipopolysaccharide (LPS); group 4: 100 micrograms of procholeragenoid (P); group 5: 80 haemagglutinating units of cell-bound haemagglutinin (CHA) adsorbed onto the surface of F-SRBC (CH-SRBC); group 6: 500 micrograms of LPS + 50 micrograms of P; group 7: CH-SRBC + 50 micrograms of P; group 8: combined vaccine formula 1 consisted of 500 micrograms of LPS, CH-SRBC and 50 micrograms of P and group 9: combined vaccine formula 2 consisted of 1,000 micrograms of LPS, CH-SRBC and 100 micrograms of P. The immunization was repeated once more 14 days later. Five days, thereafter, the rats were killed and their jejuni were removed for cryostat sectioning. Antibody producing cells against LPS (anti-LPS cells), P (anti-CT cells) and CHA (anti-CHA cells) in the intestinal lamina propria were enumerated by double antibody sandwich method of immunofluorescence using pure LPS, cholera toxin (CT) and pure CHA as the antigens in the assay, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies against Vibrio cholerae lipopolysaccharide, cell-bound haemagglutinin and toxin in the intestinal fluid during convalescence.

Specific antibodies to V. cholerae lipopolysaccharide (LPS), cell-bound haemagglutinin (CHA) and toxin (CT) in the intestinal lavages of healthy Thais and Thai cholera patients during the convalescence period were determined by enzyme-linked immunosorbent assay. Only IgM and IgA specific antibodies were detectable in the specimens. All of the persons who were just recovered from cholera had IgA anti-CT and IgA anti-LPS and 82.4% had IgA anti-CHA. The IgA anti-CT, anti-LPS and anti-CHA were detected also in the gut fluids of 70.6%, 94.1% and 88.2%, respectively, of the healthy controls. The mean levels of the IgA antibodies of all specificities between the two groups of individuals were not different. However, the IgM anti-CT and IgM anti-LPS of the cholera patients increased during the convalescence period. The levels, therefore, were significantly higher than those of the controls. The ratios of IgA anti-CT: IgM anti-CT and IgA anti-LPS: IgM anti-LPS among the patients were 2.93:1 and 2.02:1, respectively while those of the controls were 10:1 and 34:1, respectively. IgA antibodies predominated in the lavages of both groups of the individuals.

Vibriocidal antibody and antibodies to Vibrio cholerae lipopolysaccharide, cell-bound haemagglutinin and toxin in Thai population.

Vibriocidal antibody and antibodies to Vibrio cholerae lipopolysaccharide (anti-LPS), cell-bound haemagglutinin (anti-CHA) and toxin (anti-CT) were determined in Thai individuals of various age groups who lived in areas with high (H) and low (L) cholera endemicity. The enzyme-linked immunosorbent assay (ELISA) was performed to detect levels of class specific anti-LPS, anti-CHA and anti-CT. It was found that Thai individuals acquired the vibriocidal antibody early in life. Fifty percent of individuals aged 5 to 15 years old had detectable titre while more than 80% of adults had titres ranged from 1:5 to 1:125 or higher. Thai adults who lived in area with high cholera endemicity had significantly higher vibriocidal antibody levels than their counterparts who lived in area with low cholera endemicity. Lipopolysaccharide was not the only antigen responsible for stimulating the vibriocidal antibody production. Adult levels of all classes of anti-CHA from L were higher than those of H while the anti-LPS in the forms of total immunoglobulins, IgG and IgA were similar but IgM of L was higher than that of H. The levels of all classes of anti-CT from H seemed to increase with age except at the school age (5 years to 15 years old) when there were marked decreases of all antibody classes. Total immunoglobulin and IgM anti-CT at adult age of H and L were not different, although IgG anti-CT of L was higher than that of H and IgA anti-CT of H was higher than that of L.