| Vibrio cholerae is the causative agent of cholerae, an acute dehydrating diarrhea that occurs in epidemic and pandemic forms. There are 206 known serogroups of Vibrio cholerae at least. Only serogroup O1 was supposed to be responsible for epidemic and pandemic of cholerae until the emergence of serogroup O139 in 1992. Vibrio cholerae attracted the attention of scholars all of the world since typical dehydrating diarrhea which seemed to be caused by Vibrio cholerae outbreak in Madras city of India in 1992 and transmitted rapidly to more than ten countries such as Thailand, Pakistan, Burma, China, Saudi Arabia, USA, UK, Japan and so on.Vibrio cholerae Oland O139 have been both defied as the causative agent of cholerae. Even some scholars thought the Vibrio cholerae O139 could cause the eighth pandemic of cholerae perhaps. The origin of Vibrio cholerae 0139 is always a hot dot after the appearance of Vibrio cholerae 0139 in India in 1992. At the aspect of virul-ence factors and the background of heredity, the scientists found Vibrio cholerae O 139 is very similar with the El Tor biotype of Vibrio cholere which caused the seventh pandemic of cholerae. At present, there are three points about the origin of Vibrio cholerae 0 139 as follows: 1 Vibrio cholerae O139 maybe result from the mutation of the O antagen of El Tor biotype of Vibrio cholerae', 2 Vibrio cholerae O139 was derived from Vibrio cholerae non-Ol obtained virulence factors of El Tor biotpye of Vibrio cholerae by horizontal gene transfer. 3 Vibrio cholerae exists in environment previously, but it could not be detected. None of these three points can be confirmed or excluded till now. Most studys support the first point. But we still need to study further in order to confirm the origin of Vibrio cholerae.In 1993, there was an outbreak of cholera caused by Vibrio cholerae 0 139 in Xin Jiang province for the first time. Many scholars studied the molecular biology characteristics of Vibrio cholerae O139 which caused the outbreak of cholerae in Xinjiang, China. It was found that Vibrio cholerae O139 of Xinjiang is similar with Vibrio cholerae O139 of Indian and Bengal, but they still have some difference.It is indicated that Virbio cholerae Ol and O139 can become the causative agent because there are cholerae toxin unit and Vibrio cholerae pathogenicity island(VPI) in their chromosome genome. Cholerae toxin unit can produce cholerae toxin and result in dehydrating diarrhea which seemed to be caused by Vibrio cholerae. It exists in the form of the filamentous phages named CTXO. VPI can produce toxin co-regulated pi-lus. Toxin co-regulated pilus is not only a important clonization factor, but also the receptor of CTXO. It can help CTXO enter the Vibrio cholerae. Then the CTXO reco-mbine with the chromosome of Vibrio cholerae, and encode cholerae toxin.Cholera is a serious infectious disease. Up to the present, there is not a perfect vaccine. The antibody produced by TcpA can interdict Virio cholerae adherence to intestines membrance. A number of TcpA make up of toxin co-regulated pilus. Besides, toxin co-regulated pilus is the receptor of CTXO. The antibody produced by TcpA can induce immunity. So the significance of constructing pNEB193-tcpA is far-reaching in aspect of researching the biological function of TcpA and constructing cholerae vaccine.To study the origin and molecular charactes of Virbio cholerae O139 of Xinjiang further, we can study the major virulence factor tcpA and the upriver sequence of VPI of XJ89079, XJ93006 and MO45. Constructing recombinant plasmids pNEB193-tcp A establish base to research the biological functions of TcpA and construct cholerae vaccine.Methods 1 Cloning , sequencing and comparing the tcpA of genome of XJ93006, MO45 and XJ89079; 2 Cloning VC0815gene of MO45 genome named pNEB VC0815; 3 Preparing the tcpA and VC0815 probe labled with DIG; 4 Screening clones that including VC0815 and tcpA genes from the genome libraries of XJ93006 and MO45 named pCOSVC081506 and pCOSVC081545 ; 5 Drawing and comparing res... |
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