The protective immune response against infectious bronchitis virus induced by multi-epitope based peptide vaccines.

Peptide vaccine was found to be an effective and powerful approach to a variety of pathogens. To explore multi-epitope based peptide vaccines against infectious bronchitis virus (IBV), the immunogenic peptides were fused to the 3' terminal of glutathione S transferase gene (GST) and expressed in Escherichia coli. ELISA and Western blot analysis showed that the purified fusion proteins had excellent immune activity with chicken anti-IBV serum. During the vaccination course, the candidate peptide vaccines induced strong humoral and cellular response, and provided up to 80.0% immune protection, while all non-immunized chickens in the negative control group manifested obvious typical symptoms and died after virus challenge. Our finding provides a new way to develop multi-epitope based peptide vaccine against IBV.

Detection of CTX-M-15, CTX-M-22, and SHV-2 extended-spectrum beta-lactamases (ESBLs) in Escherichia coli fecal-sample isolates from pig farms in China.

The aim of the present study was to investigate the antibiotic resistance profiles and the molecular epidemiology of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates from two production swine operations in Sichuan Province, China, between August 2002 and February 2007. The prevalence of ESBL-producing E. coli increased dramatically from 2.2% to 10.7% during this period. This increase appeared mostly related to dissemination of CTX-M-type ESBLs among E. coli isolates. Of 212 E. coli isolates studied, 14 harbored ESBL genes. Among them, 13 harbored bla(CTX-M-15/22) and one harbored bla(SHV-2). To our knowledge, this is the first study to identify bla(CTX-M-22) from production animals. One isolate in 2002 harbored bla(SHV-2), indicating that ESBL genes have been present in farm animals in China since at least 2002. Molecular characterization and pulsed-field gel electrophoresis of the ESBL-producing isolates suggested that different mechanisms may be involved in the dissemination of the CTX-M genes and revealed that additional resistance determinants for non-beta-lactam antibiotics were carried by plasmids encoding certain ESBL genes. Results of this study provide an example of how ESBL genes, particularly those of CTX-M lineages, are rapidly spreading among E. coli isolates from commercial pig farms in Sichuan province of China.

Multivalent DNA vaccine enhanced protection efficacy against infectious bronchitis virus in chickens.

For efficacious DNA vaccine development against infectious bronchitis virus (IBV), the immunogenicity of a multivalent DNA vaccine was evaluated. Three expression plasmids each targeting spike protein (S1), nucleocapsid protein (N), and membrane protein (M) of IBV were prepared. Chickens were immunized with either individual plasmids (monovalent) or with a combination of all plasmids (multivalent). Immunization with the multivalent DNA vaccine induced synergistic augmentation of humoral and cellular responses in comparison with the individual vaccines, and provided up to 85% immune protection. Thus the multivalent DNA vaccine represents an innovative approach for enhancing DNA vaccine potency, and has potential clinical application for vaccination against IBV.

An effective method for isolation of DNA from pig faeces and comparison of five different methods.

Polymerase chain reaction (PCR) detection of microorganism in faecal specimens is hampered by poor recovery of DNA and by the presence of PCR inhibitors. In this paper, we describe a new modified method for extracting PCR-quality microbial community DNA from pig faecal samples, which combines the pretreatment with polyformaldehyde, and subsequent DNA lysis in the presence of CTAB, salt, PVP, and beta-mercaptoethanol, followed by isolation of nucleic acids using chloroform (no phenol) based protocol. The method resulted in a 1.3- to 11-fold increase in DNA yield when compared to four other widely used methods. Genomic DNA extracted from all five methods was assessed by both agarose gel electrophoresis and polymerase chain reaction for amplification of 16S rDNA specific fragments. The results showed that the improved method represented a reproducible, simple, and rapid technique for routine DNA extraction from faecal specimens and was notably better than using the QIAamp DNA Stool Mini Kit.

[Accessory gene regulator in Staphylococcus biofilm formation and infection].

The most important factor in the pathogenesis of biomaterial-associated Staphylococcal infections is the formation of bacterial biofilms. Biofilm formation was regulated or influenced by quorum sensing. One of the quorum sensing systems agr is genus specific which controls the expression of a series of toxins and virulence factors and the interaction with the innate immune system. New research indicates that the role of agr during infection is controversial. The research progress will play an important role in the development of novel antibacterial agents and management of device-related infection of Staphylococci.

Phenotypic and genotypic characterisation of antimicrobial resistance in faecal bacteria from 30 Giant pandas.

To study the prevalence of antimicrobial resistance in faecal bacteria from Giant pandas in China, 59 isolates were recovered from faecal pats of 30 Giant pandas. Antimicrobial susceptibility testing of the isolates was performed by the standardised disk diffusion method (Kirby-Bauer). Of the 59 study isolates, 32.20% were resistant to at least one antimicrobial and 16.95% showed multidrug-resistant phenotypes. Thirteen drug resistance genes [aph(3')-IIa, aac(6')-Ib, ant(3'')-Ia, aac(3)-IIa, sul1, sul2, sul3, tetA, tetC, tetM, cat1, floR and cmlA] were analysed using four primer sets by multiplex polymerase chain reaction (PCR). The detection frequency of the aph(3')-IIa gene was the highest (10.17%), followed by cmlA (8.47%). The genes aac(6')-Ib, sul2 and tetA were not detected. PCR products were confirmed by DNA sequence analysis. The results revealed that multidrug resistance was widely present in bacteria isolated from Giant pandas.