Publications (71) View all
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Article: Chaperonin GroEL: A novel phylogenetically conserved protein with strong immunoreactivity of Avian Pathogenic Escherichia coli isolates from duck identified by immunoproteomics.
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ABSTRACT: Avian Pathogenic Escherichia coli (APEC) is one of the most important bacterial pathogens of poultry. The lack of suitable vaccines and the emergence of multi-resistant strains have hampered the control of avian colibacillosis. To identify immunogenic proteins of APEC as vaccine candidates, immunoproteomics and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) were applied. Proteins from total cell lysates of APEC DE205B isolated from the brain of a duck with septicemia and neurological symptom in China were separated by two-dimensional electrophoresis (2-DE) and reacted with hyperimmune duck serum against DE205B. Fourteen immunoreactive spots were found, representing 11 distinct proteins. These included two predominant immunogenic components, outer membrane protein A (OmpA) and flagellin (FliC). GroEL, which is a member of the molecular chaperone family and identical structurally to eukaryotic heat shock protein 60 (Hsp60), and the other eight antigens are reported here as immunoreactive proteins of APEC for the first time. Subsequently, nine genes encoding the identified proteins were successfully cloned and expressed in E. coli BL21 (DE3). Seven of the recombinant proteins were able to react with hyperimmune duck serum and three of them, GroEL, OmpA and FliC, showed stronger immunoreactivity. Challenge studies revealed that, just like OmpA and FliC, recombinant GroEL stimulated a strong antibody response and supported protective efficacy against APEC infection in ducks. With high phylogenetic conservation, it is considered that GroEL would be an ideal immunogen of APEC for vaccine development.Vaccine 04/2013; · 3.77 Impact Factor -
Article: Characterization and Functional Analysis of AatB, a Novel Autotransporter Adhesin and Virulence Factor of Avian Pathogenic Escherichia coli.
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ABSTRACT: Autotransporter (AT) proteins constitute a large family of extracellular proteins that contribute to bacterial virulence. A novel AT adhesin gene aatB was identified in avian pathogenic E. coli (APEC) DE205B via genomic analyses. The open reading frame of aatB was 1017 bp, coding a putative 36.3 kDa protein, which contained structural motifs characteristic for AT proteins: a signal peptide, a passenger domain, and a translocator domain. The predicted three-dimensional structure of AatB consisted of two distinct domains, the C-terminal β-barrel translocator domain and an N-terminal passenger domain. The prevalence analyses of aatB in APEC indicated that aatB was detected in 26.4% (72/273) of APEC strains, which was strongly associated with phylogenetic groups D and B2. Quantitative real-time reverse transcription-PCR analyses revealed that AatB expression was increased during infection in vitro and in vivo. Moreover, AatB could elicit antibodies in infected ducks, suggesting AatB was involved in APEC pathogenicity. Thus, mutant and complement strains of aatB gene in APEC DE205B were constructed. Inactivation of aatB resulted in the reduced capacity to adhere to DF-1 cells, defective virulence in vivo, and decreased colonization capacity in lung during the systemic infection compared with wild-type strain. Furthermore, these capacities were restored in the complementation strains. These results indicated that AatB makes a significant contribution to APEC virulence through bacterial adherence to host tissues in vivo and in vitro. In addition, biofilm formation assays for strain AAEC189 expressing AatB indicated that AatB mediates biofilm formation.Infection and immunity 04/2013; · 4.21 Impact Factor -
Article: Comparative genomic analysis of twelve Streptococcus suis (pro)phages.
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ABSTRACT: Streptococcus suis (S. suis) is an important pathogen that can carry prophages. Here we present a comparative genomic analysis of twelve (pro)phages identified in the genomes of S. suis isolates. According to the putative functions of the open reading frames predicted, all genomes could be organized into five major functionally gene clusters involved in lysogeny, replication, packaging, morphogenesis and lysis. Phylogenetic analyses of the prophage sequences revealed that the prophages could be divided into five main groups. Whereas the genome content of the prophages in groups 1, 2 and 3 showed quite some similarity, the genome structures of prophages in groups 4 and 5 were quite distinct. Interestingly, several genes homologous to known virulence factors, including virulence associated protein E, a toxin-antitoxin system and a DNA methyltransferase were found to be associated with various (pro)phages. This clearly indicates that these (pro)phages can contribute to the virulence of their hosts.Genomics 04/2013; · 3.02 Impact Factor -
Article: Characterization and genome sequencing of a novel bacteriophage infecting Streptococcus agalactiae with high similarity to a phage from Streptococcus pyogenes.
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ABSTRACT: A novel bacteriophage, JX01, specifically infecting bovine Streptococcus agalactiae was isolated from milk of mastitis-affected cattle. The phage morphology showed that JX01 belongs to the family Siphoviridae, and this phage demonstrated a broad host range. Microbiological characterization demonstrated that nearly 90 % of JX01 phage particles were adsorbed after 2.5 min of incubation, that the burst size was 20 virions released per infected host cell, and that there was a latent period of 30 min. JX01 was thermal sensitive and showed acid and alkaline resistance (pH 3-11). The genome of JX01 was found to consist of a linear, double-stranded 43,028-bp DNA molecule with a GC content of 36.81 % and 70 putative open reading frames (ORFs) plus one tRNA. Comparative genome analysis revealed high similarity between JX01 and the prophage 315.2 of Streptococcus pyogenes.Archives of Virology 03/2013; · 2.11 Impact Factor -
Article: Complete Genome Sequence of the Streptococcus suis Temperate Bacteriophage ϕNJ2.
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ABSTRACT: Streptococcus suis is an important cause of meningitis, arthritis, and sudden death in young piglets and of meningitis in humans. A novel temperate S. suis-specific bacteriophage (ϕNJ2) was identified. The phage was induced from the S. suis strain NJ2 by using mitomycin C, and the whole genome sequence was determined. The ϕNJ2 genome is 37,282 bp in length and contains 56 open reading frames (ORFs). While 31 ORFs (55%) encoded hypothetical proteins, other ORFs were predicted to be functional, clearly indicating the novelty of ϕNJ2.Genome announcements. 01/2013; 1(1).
