CrossRef 23. Solomon PS, Ipcho SVS, Hane JK, Tan K-C, Oliver RP: A quantitative PCR approach to determine gene copy number. Fungal Genetics Reports 2008, 55:5–8. Author’s contributions JPG carried out most of the experiments and participated in the drafting of the manuscript. RPO and RDG participated in the design of the study and the interpretation of the data. PSS conceived the study, participated in the experiments and wrote the manuscript. All authors read and approved the final manuscript.”
“Background H. pylori is a microaerophilic, spiral shaped Gram-negative bacterium that chronically infects the gastric mucosa . It is recognised as a
human pathogen associated with chronic gastritis , peptic ulcer  and gastric cancer , the SB203580 order development of which are related to the virulence factors cytotoxin associated antigen (CagA) [4, 5] and vacuolating cytotoxin A (vacA) [6, 7]. It has been reported Torin 1 in vivo that CagA and VacA polymorphisms are associated with distinct pathological features in H. pylori infected adults with gastrointestinal diseases [8–14]. CagA has emerged as a major virulence factor for gastroduodenal disease severity, including an increased cancer risk [9, 15]. CagA is injected into epithelial cells mediated
by a type IV secretion system [4, 16, 17]. In the host cell, CagA localises to the inner surface of the plasma membrane and becomes phosphorylated on specific tyrosine residues within repeating penta amino acid Glu-Pro-Ile-Tyr-Ala (EPIYA)
motifs present at the C-terminus of the protein [18–20]. This part of the protein is encoded by the variable 3’-region of the cagA gene [4, 5, 21, 22] (Figure 1). Four different cagA EPIYA motifs have been defined according to the amino acid sequence that surrounds the EPIYA residues; EPIYA-A, -B, -C and -D [20, 22–25]. CagA toxins nearly always possess EPIYA-A and EPIYA-B, followed by varying numbers of EPIYA-C in Western-type isolates . In East Asian-type of clinical H. pylori isolates, EPIYA-A and -B are, on the other hand, commonly followed by an EPIYA-D motif [24, 25]. It has been suggested that the considerable variation in number of repeating EPIYA-C motifs at the C-terminus of the protein may alter the biological activity of CagA in phosphorylation-dependent Mannose-binding protein-associated serine protease as well as phosphorylation-independent ways [20, 26]. It was suggested that the number of cagA EPIYA-C motifs and the tyrosine phosphorylation status of CagA are important risk factors for gastric cancer among Western strains . This is also supported by a higher risk of cancer development in strains with a high degree of phosphorylation . Figure 1 A) Schematic illustration of the H. pylori 26695 cagA gene. M13-CagA.epiya.se and T7-CagA.epiya.as indicate the position of the primers used in PCR amplification. B) Amino acids flanking the EPIYA motifs present in EPIYA-A, EPIYA-B, and EPIYA-C segments of H. pylori 26695.