Identification of genes in biotype 2 Vibrio vulnificus virulence plasmid associated with survival of this organism in eel serum

• Main Authors: Cheng-YuanHsieh, 謝政原
• Other Authors: Lien-I Hor
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/26279595389279044051

碩士 === 國立成功大學 === 微生物及免疫學研究所 === 98 === Vibrio vulnificus is a marine bacterial species pathogenic for humans and eels. There are three biotypes (BTs) of V. vulnificus, and the strains virulent for eels are classified as BT2. We have previously demonstrated that the BT2 strains possess a common plasmid that is associated with their virulence in eels. A gene, vep07, carried by the virulence plasmid, pR99, of a BT2 strain was found to be essential for bacterial virulence in eels. However, this gene alone in a plasmid-cured strain did not confer the virulence for eels, indicating that other genes in the virulence plasmid might be involved. Both the virulence plasmid and vep07 are required for the bacterial resistance to killing by eel serum. In the study we identified other virulence genes in the plasmid by screening for mutants with reduced resistance to eel serum. A mutant bank has been constructed by transposon mutagenesis with a mini-Tn10-carrying plasmid, pBSL181. The virulence plasmids with mutations have been transferred to a strain cured of the virulence plasmid with the help of a conjugative plasmid. Three mutants with reduced resistance to eel serum have been thus isolated and the mutated genes have been mapped. The association of vep71 one of these genes and is annotated as a hypothetical protein, with resistance to eel serum has been confirmed. The function of vep71 needs to be further studied. We have also mapped those mutations in those with normal survival in eel serum in pR99.