| Summary: | 碩士 === 東吳大學 === 微生物學系 === 94 === Vibrio parahaemolyticus causes the most of the food poisoning cases in Taiwan. In 1996, a new O3:K6 serovar became widespread in India and caused pandemic spreading throughout the world. Before the occurring of this new O3:K6 strain, V. parahaemolyticus had not caused pandemics. From the study of V. cholerae bacteriophages, it is known that bacteriophages can transfer virulence genes to non-pathogenic strains and make them pathogenic. Bacteriophage in V. parahaemolyticus may also be important in the virulence and other phenotypic changes. This study analyzed the bacteriophage VP882 which lysogenized in new O3:K6 V. parahaemolyticus 882. We extracted its nucleic acid, sequenced and analyzed the genome. The results showed the nucleic acid of this phage to be a double stranded linear form DNA. The DNA sequence of this phage consisted of 38,197 base pairs with 51 putative open reading frames (ORF). Functions could be assigned to 25 putative gene products, based upon bioinformatic analysis. The VP882 genome was organized in a modular format and included modules for replication, DNA packaging, and structural proteins, but lacked the modules for lysogeny and host cell lysis. The SDS-PAGE analysis of the phage structure protein showed that there were three protein bands, namely, 70, 60 and 32 kDa, probably the gene products of ORF 8, ORF 5 and ORF 13, respectively.
There were two special proteins predicted not belong to phage proteins. The predicted protein of ORF40 was homologous to the LuxR protein of V. parahaemolyticus. LuxR is related to fluorescence in Vibrio strains. Recent research also found that LuxR could affect the expression of virulence genes. ORF 38 was a ParA protein which involves in vector replication. In assaying the host range, 19 of 30 V. parahaemolyticus strains, four of five V. cholerae strains and two of five V. vulnificus strains were susceptible to the lysis of VP882. The VP882 may be important in the regulation of virulence genes and in the intra- and interspecific horizontal gene transfer influencing the evolution of vibrios.
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