Characterization of recombinant antibodies developed for capturing enterohemorrhagic Escherichia coli O157:H7.

Escherichia coli O157:H7, an emerging cause of food-borne disease with the occurrence of an estimated 20,000 illnesses and 250 deaths each year in the United States, has now been reported from several countries worldwide. Infections with this bacteria, which follows the ingestion of contaminated food by humans, causes bloody diarrhea, hemolytic uremic syndrome (HUS), and renal disease, that can have serious health implications. The source of food contamination is usually associated with animals, mainly cattle. Many cattle become infected early in life when they are exposed to an environment that is contaminated by other animals shedding the organisms in their feces. Detection of E. coli O157:H7 in feces or contaminated food samples requires tests with high sensitivity, which is increased by the use of monoclonal antibodies. However, the production of concentrated monoclonal antibodies in ascites raises animal welfare concerns, and can be expensive. In this study, single chain of variable fragment (scFv) molecules were developed from hybridoma clones that produce immunoglobulins specific for the LPS and flagella antigen of E. coli O157:H7 using phage display technology. The reactivity of the soluble scFv for their respective antigens was preserved in ELISA and by partial inhibition of bacterial agglutination with polyclonal antiserum. Furthermore, the scFv were able to capture E. coli O157:H7 bacteria demonstrating their potential use in diagnostic assays.

Role of cell surface antigens of Vibrio cholerae 01 and non 01 serovars in intestinal adhesion.

Decrease in adherence of Vibrio cholerae to rabbit small intestine was observed following treatment with antisera against outer membrane (OM), lipopolysaccharide (LPS) and flagella. Anti LPS antibodies were more efficient than the other two antibodies in inducing adherence inhibition and promoting in vivo protection.

Expressäo do flagelo em sorotipos imóveis de Escherichia coli enteroinvasora / Expression of the non motile flagellum in enteroinvasive Escherichia coli serotypes

No presente estudo, a observação de dez sorotipos imóveis de EIEC em microscópio eletrônico levou à descoberta de flagelos em todos os sorotipos estudados, em quantidades que variaram de um a cinco filamentos. A produção do flagelo de EIEC (FLIEC) não foi influenciada pela temperatura, mas o nível de expressão dependeu da cepa e do meio. A maioria das cepas foi móvel em meios de cultura com baixa porcentagem de ágar (0,17-02 por cento). A preparação parcialmente purificada contendo FLIEC, identificado pela ME, foi submetida à técnica de SDS-PAGE. Uma banda de 77kDa, que é relativamente maior do que a massa molecular das flagelinas de outras bactérias entéricas, foi encontrada nessa preparação. Essa banda reagiu com vários soros anti-flagelina de diferentes anterobactérias...

Participacion de epitopes flagelares de Campylobacter jejuni en la adhesion celular / Partipation of Campylobacter jejuni flagellar epitopes in cellular adhesion

Utilizando una cepa flagelada (052) y una aflagelada (T-1), se estudió la participación de epítopes flagelares de C. jejuni en la adhesión a células HEp-2 in vitro. La cepa 052 presentó una capacidad de adhesion significativamente mayor que la cepa T-1. Cuando los ensayos de adhesión fueron realizados en presencia de anticuerpos monoclonales dirigidos contra epítopes flagelares, la capacidad de adhesión de la cepa 052 experimentó una inhibición que fluctuó entre 64,3 y 92,9 por ciento. Mediante una prueba de ELISA se comprobó que estos anticuerpos monoclonales eran específicos y estaban dirigidos exclusivamente contra epítopes flagelares de la cepa 052, no reaccionando con la cepa T-1. Estos resultados demuestran que epítopes flagelares de C. jejuni estarían participando en el proceso de adhesión, sugiriendo la intervención del flagelo en la instalación del proceso infeccioso.

Intervención del flagelo de campylobacter jejuni subsp. jejuni en la adherencia a cultivos celulares: evidencias bacteriológicas e inmunológicas / Intervention of campylobacter campylobacter jejuni subsp. jejuni flagella in the adhesion to cellular cultures: bacteriological and immunological evidences

The participation of the flagella of a virulent strain (O52) of campylobacter jejuni subsp. jejuni in the adhesion to HEp-2 cells and their inhibition by means of homologous polyclonal antibodies, moniclonal antiflagella antibodies and colostral natural antibodies (IgA) was studied. An aflagellated strain (T1) was used as negative control. Adhesion was observed in higher rates with O52 strain (72 percent) than with T1 strain (27,5 percent). Polyclonal, monoclonal and colostral antibodies inhibited O52 strain adhesion in more than 70 percent (p<0,001). T1 strain adhesion was inhibited only by polyclonal and colostral natural antibodies. Our results suggest that the flagella of C. jejuni subsp. jejuni could participate effectively in the adhesion process. However, the inhibition of T1 strain by polyclonal and colostral antibodies suggest the existence of other kinds of adhesins in the bacterial surface

Mechanism of complement-independent and antibody-mediated killing of Leishmania donovani promastigotes.

Immune serum raised against flagellar fraction of Leishmania donovani isolate UR6 has profound lethal effect on the in vitro growth of the parasite. Lethal effect of immune serum was also examined using two other isolates of L. donovani, namely DD8 and AG83. It was observed that immune serum is equally effective against UR6 and DD8 but has no effect on AG83 promastigotes. Parasite killing is mediated by Leishmania-specific antibodies in the absence of complement or any other factors present in rabbit serum. Results indicate that the lethal effect of immune serum is due to impairment in membrane function leading to inhibition in uptake of essential nutrients needed for growth and survival of parasites.