Xiaotao Zeng

Academy of Military Medical Sciences, T’ien-ching-shih, Tianjin Shi, China

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Publications (7)16.47 Total impact

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    ABSTRACT: Streptococcus suis (S.suis) is an important emerging worldwide pig pathogen and zoonotic agent with rapid evolution of virulence and drug resistance. In this study, we wanted to investigate the effect of licochalcone A on growth and properties of Streptococcus suis. The antimicrobial activity of licochalcone A was tested by growth inhibition assay and the minimal inhibitory concentrations (MICs) also were determined. The effect of licochalcone A on S.suis biofilm formation was characterized by crystal violet staining. The effect of licochalcone A on suilysin secretion was evaluated by titration of hemolytic activity. To understand the antimicrobial effect, gene expression profile of S.suis treated by licochalcone A was analyzed by DNA microarray. Our results demonstrated that licochalcone A showed antimicrobial activity on S.suis with MICs of 4 µg/ml for S.suis serotype 2 strains and 8 µg/ml for S.suis serotype 7 strains. Biofilm formation was inhibited by 30-40% in the presence of licochalcone A (3 µg/ml) and suilysin secretion was also significantly inhibited in the presence of licochalcone A (1.5 µg/ml). The gene expression profile of S.suis in the presence of licochalcone A showed that 132 genes were differentially regulated, and we analyzed the regulated genes in the aspect of the bacterial cell cycle control. Among the deregulated genes, the genes responsible for the mass doubling was increased expression, but the genes responsible for DNA replication and cell division were inhibited the expression. So, we think the regulation of the cell cycle genes might provide a mechanistic understanding of licochalcone A mediated antimicrobial effect against S.suis.
    PLoS ONE 01/2013; 8(7):e67728. · 3.73 Impact Factor
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    ABSTRACT: [This corrects the article on p. e67728 in vol. 8.].
    PLoS ONE 01/2013; 8(7). · 3.73 Impact Factor
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    ABSTRACT: The VjbR protein induced antibody responses in both human and animal brucellosis, and the vjbR mutant 16MΔvjbR is an ideal vaccine candidate because of the feasibility of using the VjbR as diagnostic antigen. To further characterize this vaccine candidate and provide information for vaccine development, in the present study, a whole genome DNA microarray of 16M were used to compare the transcriptome of the vjbR mutant to that of the wild type strains. A total of 126 genes were greatly differentially expressed in the vjbR mutant. A great proportion of virB and flagellar genes were differentially expressed in the vjbR mutant, implying that the vjbR regulate expression of virulence genes by sensing intracellular environments. Interestingly, the virB genes are regulated by the vjbR in independent manners as shown by their different fold changes and transcription abundances. A number of genes involved in translation, stress response, amino acid transport and metabolism, cell wall/membrane biogenesis, energy production and conversion, translation were differentially expressed. The vjbR mutant showed increased sensitivity to stresses of nutrition limitation, oxidative stress and acidification, and decreased survival in macrophage and mice, being consistent with its transcription profiles. These results indicated that the quorum sensing regulator vjbR could sense intracellular environments and response to them by regulate expression of virulence genes and other intracellular survival related genes, and therefore contribute to Brucella survival in host cells. This also provided direct evidence for the rational vaccine design by using antigenic global regulator for future development of genetically marked vaccine for brucellosis.
    Indian Journal of Microbiology 12/2012; 52(4):575-580. · 0.46 Impact Factor
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    ABSTRACT: Streptococcus suis serotype 2 (S. suis S2) is able to cause human infections ranging from superficial wounded skin infections to severe invasive infections such as meningitis and streptococcal toxic shock-like syndrome. During its infection cycle, S. suis S2 must acclimatize itself to temperature shift. Herein, a whole-genome DNA microarray was used to investigate the global transcriptional regulation of an invasive strain of S. suis S2 grown to late-exponential phase at 29°C or 40°C relative to 37°C. The differentially regulated genes that were detected included those encoding virulence factors, antigenic proteins, ATP-binding-cassette transporters, and proteins of unknown functions. Our data provided a global profile of gene transcription induced by temperature alteration and shed light on some unforeseen lines for further pathogenesis investigation.
    Vector borne and zoonotic diseases (Larchmont, N.Y.) 03/2011; 11(3):215-21. · 2.61 Impact Factor
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    ABSTRACT: An acidic environment is frequently found in phagocytes, while the intracellular survival and growth of Streptococcus suis serotype 2 (S. suis S2) in phagocytes is an essential part of the infection cycle of this pathogen. In this study, we used DNA microarrays to analyze the gene expression profile of S. suis S2 in response to acidic treatment. A total of 196 genes were differentially regulated when S. suis S2 was grown at pH5.8 relative to at pH7.2, especially including the inducible transcription of genes that encoded two-component regulatory systems, protection and repair functions, and intracellular pH homeostasis. The data showed that S. suis S2 is capable of employing diverse responsive mechanisms to protect against or adapt to acidic stress. Keywords Streptococcus suis serotype 2–Expression profile–Acid stress–Microarray
    Annals of Microbiology 01/2011; 61(3):505-510. · 1.55 Impact Factor
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    ABSTRACT: We developed and evaluated a whole-genome DNA microarray of Vibrio parahaemolyticus. Based on the genomic sequences of V. parahaemolyticus, we chose a total number of 4770 genes, amplified them by PCR with specific primers, purified the PCR products and printed them onto glass slides. We performed two sets of hybridizations by the method of two-fluorescence comparative hybridization to evaluate the microarray quality, followed by PCR method to validate parts of microarray results. Microarray hybridization results were completely consistent with theory expectations and PCR verification results. We successfully developed a batch of good quality whole-genome DNA microarrays of V. parahaemolyticus, built up a method of microarray-based comparative genomic hybridization of V. parahaemolyticus and a set of microarray data analysis standard method.
    ACTA MICROBIOLOGICA SINICA 04/2010; 50(4):548-53.
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    ABSTRACT: Outbreak of V. parahaemolyticus infections occurred since 1996 was linked to a proposed clonal complex, the pandemic group. The whole genome sequence provides an unprecedented opportunity for dissecting genome plasticity and phylogeny of the populations of V. parahaemolyticus. In the present work, a whole-genome cDNA microarray was constructed to compare the genomic contents of a collection of 174 strains of V. parahaemolyticus. Genes that present variably in the genome accounted for about 22% of the whole gene pool on the genome. The phylogenetic analysis of microarray data generated a minimum spanning tree that depicted the phylogenetic structure of the 174 strains. Strains were assigned into five complexes (C1 to C5), and those in each complex were related genetically and phylogenetically. C3 and C4 represented highly virulent clinical clones. C2 and C3 constituted two different clonal complexes 'old-O3:K6 clone' and 'pandemic clone', respectively. C3 included all the 39 pandemic strains tested (trh-, tdh+ and GS-PCR+), while C2 contained 12 pre-1996 'old' O3:K6 strains (trh+, tdh- and GS-PCR-) tested herein. The pandemic clone (post-1996 'new' O3:K6 and its derivates O4:K68, O1:K25, O1:KUT and O6:K18) might be emerged from the old-O3:K6 clone, which was promoted by acquisition of toxRS/new sequence and genomic islands. A phylogenetic intermediate O3:K6 clade (trh-, tdh- and GS-PCR+) was identified between the pandemic and old-O3:K6 clones. A comprehensive overview of genomic contents in a large collection of global isolates from the microarray-based comparative genomic hybridization data enabled us to construct a phylogenetic structure of V. parahaemolyticus and an evolutionary history of the pandemic group (clone) of this pathogen.
    BMC Genomics 12/2008; 9:570. · 4.40 Impact Factor