Construction of a prokaryotic expression system of vacA gene and detection of vacA gene, VacA protein in Helicobacter pylori isolates and ant-VacA antibody in patients’ sera

Figure 1 The target amplification products with whole length of vacA gene from H pylori strain NCTC11637 and partial frag-ment of vacA gene from a H pylori isolate. Lane 1, DNA marker; lane 2, an amplification fragment of complete vacA gene from H pylori strain NCTC11637; lane 4, an amplification fragment of partial vacA gene from a H pylori isolate; and lanes 3 and 5, blank controls.

Figure 2 Nucleotide and putative amino acid sequences of vacA gene from H pylori strain NCTC 11637. Note: Underlined areas indicate the position of primers; C, T, C and A are replaced by t, c, g and g in the n

Figure 3 Expression of rVacA induced by IPTG at different concentrations. Lane 1, the protein marker; lanes 2-4, IPTG at 1.0, 0.5, 0.1 mmol/L respectively; lanes 5 and 6, bacterial pre-cipitate and supernatant with IPTG at 0.5 mmol/L, respectively; and lane 7, the negative control.ucleotide sequence from strain NCTC 11637, respectively, but the encoded amino acid residuals are not altered (are the changes correct?). “*” means stop codon.

Figure 4 Western blot result of rabbit antibody against whole cell of H pylori and rVacA. Lane 1, rVacA expressed by pET32a-vacA-E.coliBL21DE3; and lane 2: negative control of E.coliB L21DE3.