Construction of the life cycle of Angiostrongylus cantonensis in laboratory / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct the life cycle of Angiostrongylus cantonensis (A.cantonensis) in laboratory condition.</p><p><b>METHODS</b>SD rats were infected orally with the third-stage larvae of A.cantonensis collected from Jiangmen, Guangdong province. Six weeks after infection, the first-stage larvae were isolated from fresh feces of the rats by using Baermann funnel to infect 25 second-generation white jade snails raised in laboratory at the daily dose of 300 000 for 3 consecutive days. Three weeks later, the snails were dissected for counting the third-staged larvae of A.cantonensis, and those positive for A.cantonensis infection were fed directly to 10 fasting rats. The serum samples of the rats were then collected 2 weeks later for examination of specific antibodies using ELISA. The feces of the infected rats were examined microscopically after 6 weeks, and the brain, heart and lungs of the infected rats were dissected to observe the larvae at 3, 5, and 8 weeks, respectively.</p><p><b>RESULTS</b>The 3-stage larvae of A.cantonensis were found in the second-generation snails 3 weeks after infection. The positivity rate of serum specific antibodies was 100% in the 10 rats 2 weeks after feeding of the infected snails. The 1-stage larvae were detected in the feces of the rats 6 weeks after infection, and the fourth-stage larvae were found in the brain of the rats at 3 weeks, while adult worm and eggs were found in the heart and lungs of the infected rats at 5 and 8 weeks.</p><p><b>CONCLUSION</b>The successful establishment of human colon carcinoma cell line with PRL-3 gene knock-down provide a basis for investigation of the role of PRL-3 gene in the metastasis of human colorectal carcinoma.</p>

Identification and tissue localization of intermediate filament protein in Angiostrongylus cantonensis / 南方医科大学学报

<p><b>OBJECTIVE</b>To identify the type of the intermediate filament (IF) protein of Angiostrongylus cantonensis and analyze its tissue localization.</p><p><b>METHODS</b>Recombinant pET-IF of antigen IF was expressed in E.coli with IPTG induction, and the expression products were purified by His.Bind column and identified for determining the type of the IF protein by Western blotting. Anti-IF antibody was prepared by multi-spot subcutaneous injection into mouse and used to detect the tissue slices of A. cantonensis by immunohistochemical analysis.</p><p><b>RESULTS</b>The antigen IF were correctly expressed and purified, and identified as a keratin located in the intestine wall and cytoplusma.</p><p><b>CONCLUSION</b>The antigen IF is distributed in the intestine wall of A. cantonensis.</p>

Schistosoma japonicum: construction of phage display antibody library and its application in the immunodiagnosis of infection / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>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).</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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%.</p><p><b>CONCLUSIONS</b>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.</p>

A molecular epidemiological analysis of methicillin-resistant Staphylococcus aureus chromosomal cassette mec types with multiplex PCR strategy / 中华检验医学杂志

Objective To study the genotypes of 102 strains of methicillin-resistant Staphylococcus aureus(MRSA)collected consecutively in 2002 in our hospital Method Multiplex PCR was used to genotype Staphylococcal chromosomal cassette mec(SCCmec)element and its variants.Results Among 102 strains of MRSA,the genotypes were as follows:SCCmec-Ⅲ(94 strains),SCCmec-ⅢA(4 strains), SCCmec-Ⅳ(2 stains),SCCmec-Ⅰ(2 stains).Conclusion The predominant genotype of MRSA circulating in this hospital in 2002 was SCCmec-Ⅲ by multiplex PCR.