Chronic infection with Pseudomonas aeruginosa is the main proven perpetrator of lung function decline and ultimate mortality in cystic fibrosis (CF) patients. Mucoid strains of this bacterium elaborate mucoid exopolysaccharide, also referred to as alginate. Alginate-based immunization of naïve animals elicits opsonic antibodies and leads to clearance of mucoid P. aeruginosa from the lungs. Alginate was isolated from mucoid P. aeruginosa strain 8821M by repeated ethanol precipitation, dialysis, proteinase and nuclease digestion, and chromatography. To improve immunogenicity, the purified antigen was coupled to tetanus toxoid (TT) with adipic acid dihydrazide (ADH) as a spacer and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDAC) as a linker. The reaction mixture was passed through a Sepharose CL-4B column. The resulting conjugate was composed of TT and large-size alginate polymer at a ratio of about 3 : 1; it was non-toxic and non-pyrogenic, and elicited high titres of alginate-specific IgG. Antisera raised against the conjugate had high opsonic activity against the vaccine strain. The alginate conjugate was also able to protect mice against a lethal dose of mucoid P. aeruginosa. These data indicate that an alginate-based vaccine has significant potential to protect against chronic infection with mucoid P. aeruginosa in the CF host.

-In spite of increasing tendency toward Bacillus probiotics, specially Bacillus subtilis, proposed for prophylactic and therapeutic use against several gastrointestinal diseases, interaction of their spores with host cells has been poorly understood. In this study, 11 isolates out of 33 B. subtilis isolates prepared from the faeces of patients with colorectal cancer and their healthy spouses were selected according to their ability for sporulation under strict anaerobic conditions. To address what happened to their spores in contact with intestinal-like epithelial cells, adhesion and invasion assays were done on a differentiated Caco-2 cell line. The results showed that most of the clinical isolates of B. subtilis spores, in contrast to the domesticated strains; PY79 and PTCC 1365, could adhere (0.5 to 4.5%) and internalize (0.3 to 2%) to this cell line and respond to this nich by producing atypical colony morphology, probably as an adaptive marker. There were no evident differences between the spores derived from the patients and their healthy spouses in these traits. The SEM images proposed that the interaction of these spores, at least in Caco-2 cells, is probably mediated through their initial attachment to the extra cellular matrix and also due to the local changes in the cell cytoskeleton thereafter, a mechanism reminiscent of zipper-like entry in other bacteria.