Genetic and Antibiotic Resistance Characteristics of Campylobacter jejuni Isolated from Diarrheal Patients, Poultry and Cattle in Shenzhen.

OBJECTIVE: To investigate genetic and antibiotic resistance characteristics of Campylobacter jejuni (C. jejuni) isolated from Shenzhen. METHODS: Multilocs sequence typing and agar dilution methods were used to define the genotype and antibiotic resistance of C. jejuni, respectively. RESULTS: In total, 126 C. jejuni strains were isolated. The prevalence of C. jejuni was 5.3% in diarrheal patients. The prevalence in poultry meat (36.5%) was higher than that in cattle meat (1.1%). However, the prevalence in poultry cloacal swabs (27.0%) was lower than that in cattle stool (57.3%). Sixty-two sequence types were obtained, among which 27 of the STs and 10 alleles were previously unreported. The most frequently observed clonal complexes were ST 21 (11.9%), ST-22 (10.3%), and ST-403 (7.1%). ST-21, ST-45, ST-354, ST-403, and ST-443 complexes overlapped between isolates from patients and cattle, whereas ST-45 and ST-574 complexes overlapped between isolates from patients and poultry. All C. jejuni were resistant to at least one antibiotic. The highest resistance rate was toward ciprofloxacin (89.7%), followed by tetracycline (74.6%), and nalidixic acid (69.0%). CONCLUSION: This is the first report of the genotypes and antibiotic resistance of C. jejuni in Shenzhen. Overlapping clonal complexes were found between isolates from patients and cattle, and between patients and poultry.

[Compare real-time RT-PCR with two culture methods for influenza virus detection].

OBJECTIVE: Real-time RT-PCR, cell culture and embryonated eggs culture for influenza detection were compared by analyzing the data of influenza surveillance in Shenzhen in second half of 2009. METHODS: 1092 clinical samples (throat swabs) collected during second half of 2009 were tested by real-time RT-PCR, cell culture and embryonated eggs culture, and the results were analyzed by statistical methods. RESULTS: The positive rate were 54.21%, 27.11% and 16.21% using real-time RT-PCR, cell culture and embryonated eggs culture, and the sensitive were 100%, 50% and 29.9%. The lowest dilutions of virus detected by real-time RT-PCR were 10(-2) TCID50/ml. CONCLUSION: The sensitive of real-time RT-PCR was higher than culture and the specificity was also very high. It was more suitable for emergency detect. The sensitive of cell culture for H3N2 subtype was higher, and sensitive of embryonated eggs culture for type B was higher.

Schistosoma japonicum: construction of phage display antibody library and its application in the immunodiagnosis of infection.

BACKGROUND: A monoclonal antibody would be an effective tool for the detection of circulating antigens in the serum of patients with schistosomiasis, but the traditional way of producing monoclonal antibodies is not cost-effective. The objective of this study was to find a new method for the large-scale production of monoclonal antibodies against Schistosoma japonicum (Sj). METHODS: A phage display antibody library for Sj was constructed. To obtain a single-chain variable fragment antibody (scFv) against Sj, the library was screened with metabolic antigens from adult Sj worms (Sj-MAg) using enzyme-linked immunosorbent assay. The soluble scFvs selected were used to detect Sj antigens in the serum of acute and chronic schistosomiasis patients. RESULTS: Six positive clones with good reactivity to Sj-MAg were obtained from the phage display antibody library of about 1.07 x 10(6) individual clones. Only two of these six clones bound specifically to Sj-MAg and were chosen for further analysis. Specific soluble anti-Sj-MAg scFvs were produced by inducing the 2 clones with isopropyl-D-thiogalactopyranoside. The characteristics of the scFvs were then determined. The results of Western blot showed that these scFvs could bind to Sj-MAg specifically and had a molecular weight of about 31 kD. When testing serum from schistosomiasis patients with one of the two specific scFvs, its sensitivity was found to be 60% and 37% in acute and chronic patients, respectively, with a specificity of 90%. When the two specific scFvs were combined, their sensitivity was found to be 75% and 57% in acute and chronic patients, respectively, with a specificity of 85%. CONCLUSIONS: The results indicate that the scFvs are potentially useful for the diagnosis of schistosomiasis. The library construction also provides a useful tool for the further screening of other antibodies for both diagnostic and immunotherapeutic applications and for epitope analysis and vaccine design.

[Screening and identification of phage antibodies from phage display library against Schistosoma japonicum].

OBJECTIVE: To obtain single chain variable fragment(ScFv) against the circulating antigen(CAg) from Schistosoma japonicum(Sj). METHODS: Metabolic antigen of adult worm of Sj (Sj-MAg) was used in the panning of phage library against Schistosoma japonicum. The activity of Sj-MAg-binding phage clones was assayed by ELISA. The specificity of expression products of the positive clones was analyzed by ELISA, SDS-PAGE and Western blotting. RESULTS: Seventy-two randomly selected clones were tested for the presence of anti-Sj-MAg ScFvs, 6 clones showed positive. The specificity of these 6 clones was confirmed by binding them to antigens of other four trematodes. Two clones (B04, C24) were found to bind to Sj-MAg but not to any of the antigens of other four trematodes and their expression products were about 31 kDa in size. CONCLUSION: ScFv antibodies against the circulating antigens from Schistosoma japonicum Sj-MAg can be selected and manufactured from the antibody library.