Proteomics Comprison Of Salmonella Typhi And Paratyphi A

Typhoid fever was a major issue for public health in developing countries and caused about 600,000 people dead every year.Recently,paratyphoid fever became more severe than typhoid fever in some provinces in China and it is difficult to distinguish paratyphoid fever from typhoid fever only according to the symptoms caused by them.Micoarray data on shared genes indicated that S.paratyphi A and S.typhi are closely related.413 and 489 specific genes encoding different proteins were found respectively through the comparison of the genomes of S.typhi CT18 with S.paratyphi A ATCC9150.74 and 154 specific protein spots were identified with the comparison of their proteomics displayed on 2-D gels.Among the specific genes identified by genome analysis,only STY3673 gene was found expressing in proteomic spectrum of strain CT18,and SPA1555,SPA0985 expressed in strain ATCC 9150,suggesting that different protein expressing spectrum was mainly produced by modification of proteins but not specific genes contained in each genome.Within CT18 specific protein coding genes,6 genes were psuedogenes or absent in the genome of ATCC 9150,10 proteins did not express in ATCC 9150 strain but their ORFs were found present in the chromosome of ATCC 9150,47 proteins expressed in both strains were differently modified.For ATCC 9150 specific protein spots,3 were psedogenes or absent in CT18,81 proteins did not express in CT18 but their ORFs located in the chromosome DNA,77 proteins expressed both in CT18 and ATCC 9150 strains were differently modified.It is suggested that the proteomics difference between CT18 and ATCC 9150 was mainly due to different translational modification of different common genes during gene expression process indicating a economic usage of chromosome DNA in bacteria.One gene encoded different proteins with different functions.Among the specific protein spots some psuedogenes while present as active genes in the other strain caused the inactivation of the gene product,making the related metabolic pathway different.For example some genes related to the synthesis of O-antigen,catabolism of histidine and ascorbate were psuedogenes.To understand the genetic relationship of S.typhi and paratyphi A,Proteomics analysis of reference strain CT18 and 3 isolates in China was applied.19 and 64 specific protein spots were obtained between the CT18 and XJ19,28 and 54 specific spots were found between CT18 and 906005,27 and 36 specific proteins between CT18 and 1321, respectively.Primers were designed according to the sequence of the specific protein coding genes of CT18 and PCR was developed to identify these genes in China strains.As a result,one gene coding putative DNA binding protein present on the plasmid PHCM1 was not found in chromosome DNA of all China strains.It is showed the proteomics pattern of GX1321 were similar with that of CT18,while significant difference between XJ19 and 906005,indicating the close relationship in genetics between GX1321 strain and CT18 strain.With the analysis of proteomics between S.paratyphi A strain 9150 and China strains we found 15 and 17 specific proteins between 9150 and 98-53,26 and 11 proteins between 9150 and YN77,13 and 10 proteins between 9150 and 9A05036,respectively.Primers were designed according to the sequences of specific protein coding genes of 9150 and PCR was developed to check whether these genes present in China strains or not.As a result,spot number 501 and 663 were PCR amplification negative in 9A05036.Additional, a protein named yeaG,whose coding gene was not found in chromosome of 9150.Although it showed large diversity with comparing identified outer membrane proteins between S.typhi and S.paratyphi A,sequences of specific protein coding gene were conserved and only one specific protein of S.typhi was identified,named 90-38. Primers were designed according to its gene sequence,53 S.typhi strains and 49 S. paratyphi A strains were detected with PCR amplification,all S.typhi strains were positive except two,which can not agglutinate with 09 antiserum.All S.paratyphi A strains were negative.The protein was expressed in E.coli and purified.Western blot was carried out and it is showed a strong reaction with several sera from patients with typhoid fever and a weak reaction with people who had paratyphoid fever,which indicates that this protein is a potential candidate for developing diagnostic antigens in typhoid fever diagnosis.