Transcription of the Listeria monocytogenes positive regulatory factor A protein (PrfA) is initiated from either of two promoters immediately upstream of prfA (prfAp(1) and prfAp(2)) or from the upstream plcA promoter. We demonstrate that prfAp(2) is a functional sigma(B)-dependent promoter and that a sigB deletion mutation affects the virulence phenotype of L. monocytogenes. Thus, the alternat...

The virulence of Bacillus anthracis, the causative agent of anthrax, stems from its antiphagocytic capsule, encoded by pXO2, and the tripartite toxins encoded by pXO1. The accepted paradigm states that anthrax is both an invasive and toxinogenic disease and that the toxins play major roles in pathogenicity. We tested this assumption by a systematic study of mutants with combined deletions of th...

Non-aureus staphylococci (NAS) are most commonly isolated from subclinical mastitis. Different NAS species may, however, have diverse effects on the inflammatory response in the udder. We determined the genome sequences of 20 staphylococcal isolates from clinical or subclinical bovine mastitis, belonging to the NAS species Staphylococcus agnetis, S. chromogenes, and S. simulans, and focused on ...

Submit Manuscript | http://medcraveonline.com [1]. Streptococcal pharyngitis is most significant disease, and its peak incidence occurs in children, these infections impose the economic burden on the society [2]. The symptoms of streptococcal pharyngitis include a sore throat, pain in swallowing, fever, swollen, and tender lymph nodes in the neck and fatigue [3]. S. pharyngitis oftenly results ...

Epidemic Vibrio cholerae strains possess a large cluster of essential virulence genes on the chromosome called the Vibrio pathogenicity island (VPI). The VPI contains the tcp gene cluster encoding the type IV pilus toxin-coregulated pilus colonization factor which can act as the cholera toxin bacteriophage (CTXPhi) receptor. The VPI also contains genes that regulate virulence factor expression....

The amount of capsular polysaccharide formed in vitro by strains of pneumococcus types II, III, and VII of different virulence for mice has been measured by quantitative precipitin reactions. The quantity produced by strains of high virulence was greater for all three types than that formed by moderately virulent or avirulent strains. It is suggested that an important factor concerned in variat...

Helicobacter pylori (H. pylori) is a gastric human pathogen associated with acute and chronic gastritis, 70% of all gastric ulcers, 85% of all duodenal ulcers, and both forms of stomach cancer, mucosal-associated lymphoid tissue (MALT) lymphoma and adenocarcinoma. Recently, attention has focused on possible relationship between presence of certain virulence factor and H. pylori-associated disea...

Many pathogenic microbes have multiple virulence factors that can cause damage to the host and thus contribute to an overall virulence phenotype for that organism. Although current techniques are suitable for demonstrating that a particular microbial characteristic contributes to virulence, no formal approach for defining the relative contributions of multiple virulence factors to overall virul...

We investigated the genetic relationships of 54 Escherichia coli O103 strains from humans, animals, and meat by molecular typing of housekeeping and virulence genes and by pulsed-field gel electrophoresis (PFGE). Multilocus sequence typing (MLST) of seven housekeeping genes revealed seven profiles, I through VII. MLST profiles I plus III cover 45 Shiga toxin-producing E. coli (STEC) O103:H2 str...