Zymenex A/S

Pathogenesis of enterotoxigenic Escherichia coli (ETEC) infections involves colonization of the small intestine mediated by cell-surface fimbriae (CS) or colonization fimbriae antigens (CFA). However, protection against reinfection of ETEC is also conferred by somatic antigens rather than by virulence factors. To discover ETEC specific somatic antigens, the surface proteome of the ETEC H10406 strain was compared with that of non-pathogenic E. coli K12 strains. In this study, we were using stable isotope labelling with amino acids in cell culture (SILAC) technology for the labelling and relative quantification of surface proteins in order to identify polypeptides that are specifically present on ETEC strains. Outer membrane proteins were isolated, separated by gel electrophoresis, and identified by mass spectrometry. Twenty-three differentially expressed cell-surface polypeptides of ETEC were identified and evaluated by bioinformatics for protein vaccine candidates. The combination of being surface-exposed and present differentially makes these polypeptides highly suitable as targets for antibodies and thus for use in passive or active immunisation/vaccination.

Lantibiotics are a group of potent antibacterial agents that contain unusual amino acids, such as the thioether amino acids lanthionine and methyllanthionine, and the didehydroamino acids didehydroalanine and didehydro-aminobutyric acid. Here, we report on an antibacterial lantibiotic peptide named SWLP1 (Staphylococcus warneri lantibiotic peptide 1), which is secreted from Staphylococcus warneri (deposited with DSMZ, accession number DSM 16081). SWLP1 was purified from growth media. The purified peptide displays antibacterial activity against several species, including Staphylococcus epidermidis. The molecular mass of SWLP1 is 2998.9 Da as determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The sequence and possible structure was elucidated by combining electrospray ionization mass spectrometry/mass spectrometry data of ethanethiol-treated and non-ethanethiol-treated tryptic fragments of the SWLP1. SWLP1 contains three thioether bridges, one didehydroalanine, and three didehydroaminobutyric acids. This peptide has the potential to be used in treatment of several Gram-positive bacterial infections.

Two formulations of pneumococcal vaccines are currently available to prevent invasive disease in adults and children. However, these vaccines will not protect against the majority of Streptococcus pneumoniae serotypes. The use of highly conserved cell-wall-associated proteins in vaccines may circumvent this problem. A proteomics approach was used to identify 270 S. pneumoniae cell-wall-associated proteins, which were then screened in a process that included in-silico, in-vitro and in-vivo validation criteria. Five potential candidates for inclusion in a vaccine were selected, expressed in Escherichia coli, and purified for use in immunisation experiments. These proteins were detected in at least 40 different serotypes of S. pneumoniae, and were expressed in S. pneumoniae isolates causing infection. Two of the five candidate proteins, the putative lipoate protein ligase (Lpl) and the ClpP protease, resulted in a reduced CFU titre and a trend towards reduced mortality in an animal sepsis model for investigating new S. pneumoniae protein vaccines.