Attachment of Treponema denticola ATCC 35405 to laminin, a major basement membrane protein, and to other proteins was studied. Microdilution plates were coated with the proteins, and the attachment of T. denticola was measured by the enzyme-linked immunosorbent assay technique. Compared with bovine serum albumin (BSA), T. denticola had a high affinity to laminin, fibronectin, fibrinogen, and gelatin, as well as to type I and type IV collagens. Attachment to RGD peptide (Gly-Arg-Gly-Asp-Ser, the integrin recognition sequence) was only about 30% of that to laminin and was comparable to attachment to BSA. Tests with laminin fragments obtained through elastase digestion showed that the spirochetes attached well to an A-chain 140-kDa fragment involved in eukaryote cell attachment but did not attach to a 50-kDa fragment that includes the heparin binding site. Pretreatment of T. denticola with soluble laminin, fibronectin, gelatin, BSA, or fibrinogen had no effect on the attachment of the bacteria to laminin or fibronectin. A wide variety of compounds were tested for their possible inhibitory actions on the attachment. While most treatments of T. denticola ATCC 35405 had little or no effect on the attachment to proteins, sulfhydryl reagents p-chloromercuribenzoic acid (pCMBA) and oxidized glutathione inhibited the attachment by 70 to 99%, depending on the protein. When T. denticola was first allowed to attach to proteins, addition of pCMBA or oxidized glutathione could no longer reverse the attachment. Heat treatment of the spirochetes also markedly reduced the attachment to laminin, gelatin, and fibrinogen but not to BSA. Mixed glycosidase treatment of the spirochetes inhibited the attachment by 20 to 80%. None of the above treatments of the substrate proteins had any marked effect on the spirochete attachment. The results indicate that T. denticola has the capacity to bind to many different kinds of proteins by utilizing specific attachment mechanisms. The binding appears to involve protein SH groups and/or carbohydrate residues on the surface of T. denticola.
A murine hybridoma cell line, named 6A6, was developed to produce monoclonal antibodies for serological detection of European potato strains of Erwinia chrysanthemi. The monoclonal antibodies were of the immunoglobulin G2b type and were shown to react with a fimbrial antigen by immuno-gold electron microscopy, and with the fibrillin protein by Western blotting. In enzyme-linked immunosorbent assay (ELISA), the monoclonal antibody reacted with all but two strains of E. chrysanthemi isolated from potato. One non-reactive strain originated from Australia and therefore was likely a different biovar, and the other strain was of unknown origin. The monoclonal antibody also reacted with 20 out of 36 strains of E. chrysanthemi isolated from hosts other than potato. A triple-antibody ELISA test utilizing monoclonal antibody 6A6 successfully detected E. chrysanthemi in infected potato stems and tubers but sensitivity was limited to about 107 CFU/ml, compared to a sensitivity of 103 CFU/ml for a polymerase chain reaction test using published primers directed to the pectate lyase gene.
Two commercially available media, Ryan's aeromonas medium (RAM) and GSP agar pseudomonas aeromonas selective agar base (GSP) and one laboratory prepared medium, starch ampicillin agar (SAA), were compared for their ability to recover Aeromonas spp. from pure culture, raw ground beef, and spiked autoclaved ground beef samples. In all instances SAA medium proved to be superior for recovery of Aeromonas spp. Selectivity with SAA and GSP was better than with RAM with 100% of typical colonies confirming as Aeromonas spp. The incidence of motile Aeromonas spp. in ground meat samples in Eastern Canada was determined during a 1-year period using SAA as the isolation medium. Aeromonas spp. was found in 4 of 4 ground pork, chicken, turkey, and sausage samples and in 15 of 19 ground beef samples. Two hundred and ten presumptive Aeromonas isolates were characterized biochemically to the species level. Ninety-seven percent of the isolates from pork and 87% from ground beef were identified as Aeromonas hydrophila. Of the isolates from chicken and turkey, 40 and 56% respectively were found to be this latter species. The numbers of Aeromonas sobria and Aeromonas caviae isolated from these products were 30 and 20% for chicken and 8 and 16% for turkey respectively.
Outer membrane vesicles purified from Bacteroides gingivalis culture supernatant bound to serum coated hydroxyapatite (SeHA). The immobilized vesicles served as receptors for a number of species of oral streptococci. The binding of Streptococcus sangnis 12 to SeHA was increased 10 times by the vesicles. Vesicle‐associated binding increased proportionally with an increase in the number of bound vesicles. Arginine and lactose both partially reduced binding of 5. sanguis. Heating the vesicles destroyed their binding ability whereas heating S. sanguis reduced but did not eliminate vesicle‐mediated binding.
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