Passive immunization of piglets against enterotoxigenic colibacillosis by vaccinating dams with K88ac pili bearing bacterins.

Day-old-piglets were passively immunized by vaccinating the pregnant sows with K88ac enterotoxigenic Escherichia coli (ETEC) vaccine. High level of ETEC specific antibodies was excreted in colostrum (3733.33 +/- 1152.13) and maintained a detectable level (100.00 +/- 0.00) up to 21 day post partum (DPP). The IgG was the predominant immunoglobulin followed by IgA and IgM. Piglets born of vaccinated dam (group A) and unvaccinated dam (group B) were challenged in 7 day of age. Clinical and faecal scores were significantly (P < 0.01) low in group A than that of group B. Piglets of group A developed mild diarrhoea (33.33%), while all the control piglets developed profuse diarrhoea and 3 of these died before 14 day of challenge infection.

Epítopos continuos y comunes presentes en las fimbrinas de Escherichia coli enterotoxigénica (ETEC) / Common continuos epitopes present in enterotoxigenic escherichia coli (ETEC) fimbriae

Escherichia coli enterotoxigénica (ETEC) es un agente causal de diarrea. ETEC cuenta con factores antigénicos de colonización (CFAs y PCFs), que son importantes en la virulencia. Los anticuerpos contra los CFAs son producidos al término de la infección por ETEC y han mostrado ser protectores contra la enfermedad. Sin embargo, los epítopos en CFA/I, los cuales inducen protección, no han sido caracterizados. El objetivo de este estudio es la detección de los epítopos continuos y comunes en CFA/I de ETEC, a nivel molecular, que conduzcan al desarrollo de métodos para la prevención de la enfermedad causada por ETEC. Se sintetizaron octapéptidos continuos unidos a fase sólida que comprendían a todo la secuencia de CFA/I por el método de Geysen para el escrutinio, con sueros de niños infectados por ETEC, con sueros de adultos de zona endémica y no endémica con el anticuerpo monoclonal CAF/I 1:6 (Mab CFA/I 1:6) y con los sueros hiperinmunes contra CFAs y PCFs diferentes a CFA/I. Los sueros de los niños, de los adultos de zona endémica y los sueros hiperinmunes reconocieron tres epítopos continuos y comunes en CFA/I. El Mab CFA/I 1:6 no reconoció nungún epítopo continuo

Determination of the efficiency of K99-F41 fimbrial antigen vaccine in newborn calves

Semipurified K99 and F41 fimbrial antigens were used to prepare an oil-emulsified vaccine against bovine enterotoxigenic colibacillosis. Nine Nelore cows about 7 months pregnant were divided into 3 groups (A, B and C) of 3 animals each, which received different doses of vaccine (1,500 HU, 750 HU and 380 HU, respectively) 8 and 2 weeks before delivery, in the neck by the subcutaneous route. As a control (group D), 3 pregnant cows of the same breed were not vaccinated for later challange of their calves. Vaccine efficiency was measured by the serological tests double diffusion and ELISA. Challenge of calves from the vaccinated and from the three control unvaccinated cows was carried out with the virulent Escherichia coli B41 strain (0101), STa+, K99+, F41+). Two of the 3 calves from unvaccinated cows died within 48 h with acute diarrhea. E. coli B4 was recovered as pure culture from their stools. In contrast, none of the calves born from vaccinated cows presented diarrhea. These data suggest that the antibody transfer to calves through colostrum gave full protection aginst the challenge. This semipurified fimbrial vaccine against K99-F41-harboring strains is the first oil-emulsified immunogen prepared in Brazil, which was not only efficient, but also had no adverse effects on vaccinated pregnant cows

Humoral immune response anti K99 pilus from enterotoxigenic Escherichia coli in experimentally inoculated calves

The bovine model is extremely interesting to study several basic aspects of mucosal local immunity. Many reports have shown that, in young calves, the infectivity of enterotoxigenic Escherichia coli may be inhibited by passively administered antibodies anti K99 pilus. We have measured, by immunoradiometric assays, the IgG response anti K99 pilus in the serum of calves, deprived of colostrum and orally inoculated with enteropathogenic K99+ E. coli. Although variable levels of IgG anti K99 pilus were detected, their protective value could not be ascertained in vivo due to the acute development of the infection. In an effort to correlate the presence of serum antibodies anti K99 pilus with their protective capacity, an ex-vivo assay to monitor the interaction of radiolabeled K99 pilus with the bovine mucosa was standardized. Paradoxically, although K99 pilus, purified by standard procedures, was recognized by polyclonal rabbit and calf antisera, its interaction with the bovine intestinal mucosa, quantitated in the ex-vivo system, was not inhibited by these reagents, indicating that the antibodies did not effectively block those K99 pilus domains involved in the interaction with mucosal receptors

Aplicación de la técnica de hemaglutinación para la detección de fimbrias en cepas de Escherichia coli aisladas de niños con enfermedad diarreica aguda en Cuba / Application of the hemagglutination technique to detect fimbriae in Escherichia coli strains isolated from children with acute diarrheal in Cuba

Se estudia un total de 26 cepas de Escherichia coli, aisladas de niños con enfermedad diarreica aguda en el Laboratorio Nacional de Referencia de Enfermedades Diarreicas Agudas (EDA) del Instituto de Medicina Tropical "Pedro Kourí", con el objetivo de demostrar la presencia de fimbrias como factores de virulencia, mediante la técnica de Rutter y Jones. De las 26 cepas estudiadas 8 hemoglutinaron para el 30,7 por ciento , de ellas 3 resultaron ser resistentes a la inhibición de la hemaglutinación con D-manosa