RNA interference (RNAi) is an effective antiviral mechanism of human body. It is a sequence specific process involving post transcriptional gene silencing initiated by double stranded RNA (dsRNA) homologous to the silenced genes. RNAi,as a genomic immune phenomenon involving the modulation of specific gene expression and an efficient gene-level defense mechanism against viral infection,has become the focus of study in biomedicine. This review summarized the researches of RNAi in inhibiting hepatitis virus infection,analyzed the advantages of RNAi in clinical treatment of hepatitis,and pointed out the existing problems,hoping to provide references for antiviral study of hepatitis infection.

Based on the concept of general education in higher education,Zhongshan school of medicine of Sun Yat-sen University launched general education course-‘ basic medicine introduction' to all non-medical undergraduates.Teaching contents,teaching methods and teaching effects of this course were explored and evaluated.By introducing basic medicine,the overall objective is to guide students to consciously maintain the mental and physical health and to stimulate students' thinking on the meaning of life.

Objective To establish a rapid, specific and sensitive diagnostic technique for the human T. gondii infection with hematopoietic stem cell transplantation and discuss its clinical significance. Me- thods Fifty-six patients subject to hematopoietic stem cell transplantation were detected with ELISA and PCR. Results Among 56 recipients of hematopoietic stem cell transplantation, 7 were positive for T. gondii antigen and 10 were positive for SAG3 gene fragment respectively with the positive rate being 14.3 % and 17.8 % in the ELISA and PCR screening respectively. Twenty healthy people were negative for anti-Toxo antibody.Conclusion PCR is an accurate, relatively rapid, sensitive and specific method for detecting SAG3 gene of T. gondii, and can be considered a valuable additional tool for identification of T. gondii infections.

Objective To obtain and characterize a novel gene of Schistosoma japonicum. Methods Looking for a novel gene through expressed sequence tags(EST),then predicting its function with the help of software on line. Finally the novel gene was cloned into an eukaryotic plasmid pEGFP N3. Results A novel gene with complete ORF was obtained. It has homogeneity with Defender Against Apoptotic Death 1 of human and pig. Conclusions EST is a good method to find new genes and analyse them with the help of software on line and characterize their function.

Objective To clone the gene of autolysin(LytA) which are from different clinical strains of Streptococcus pneumoniae and express them in Escherichia coli. Methods The LytA gene was amplified by PCR from the total DNA of S.pneumoniae. Primers were designed according to the LytA gene sequence of R6. Recombinant plasmids were constructed and the sequences of different clinical strains were analyzed through method of bioinformatics. The cloned genes were expressed in E.coli and detected by SDS-PAGE. Results Complete LytA gene were amplified from all of the different clinical strains of S.pneumoniae and recombinant plasmids pGEX-4T-1-LytA were constructed successfully. After comparing the sequence of DNA and supposed protein, we find some differences. Induced by IPTG, LytA gene was expressed effectively in E.coli Jm109. Result of SDS-PAGE showed that the molecular weight of expressed protein was 62 kD, the same as calculated. Conclusions The sequences encoding LytA from different clinical strains of S.pneumoniae were cloned, the recombinant plasmids pGEX-4T-1-LytA was constructed successfully. Sequence analysis showed that there have difference among the gene and amino acid sequences of LytA from different clinical strains. Further studies should be focused on whether the difference contributes to activity of autolysin and the drug-resistance of S.pneumoniae.

Objective To construct prokaryotic recombinant plasmids of transcriptional co-activator (TC) gene of Clonorchis sinensis, express and purify the recombinant protein and analyze its biological function. Methods A pair of primers was designed according to the known sequence of TC gene. The TC gene fragment was amplified by PCR. After purification and digestion with BamHⅠ and SalⅠ , the TC gene was connected to the prokaryotic expression vectors, pGEX-4T-1 and pET30a(+). By cloning target gene into these vectors, pGEX-4T-1 and pET30a(+), prokaryotic recombinant plasmids of TC gene were constructed and transferred into E.coli BL21. The positive expressed recombinants were detected by SDS-PAGE and Western blotting. Immobilized metal (Ni 2+ ) chelation affinity chromatography was used to purify His-TC produced by the expression of the recombinant protein pET30a(+)-TC. Results The recombinant plasmids, pGEX-4T-1-TC and pET30a(+)-TC, were constructed successfully. SDS-PAGE testified that the molecular weight of the recombinant protein was correct. Western blot analysis of GST-TC recombinant protein testified that the recombinant protein could be recognized by immunized rabbit serum, which means the protein is GST-immune active and the clone can express recombinant Clonorchis sinensis antigen. After affinity chromatography of the pET-TC protein, there was only one protein band with expected size on the SDS-PAGE gel. Conclusion The TC gene was screened from cDNA library of adult Clonorchis sinensis, cloned, expressed and purified. The purified protein of TC gene will be of importance for further research on the biological function of the gene.

Objective To evaluate the teaching activity on public health courses from clinical medical students in our university in order to provide a scientific basis for improving the curriculum design and teaching reform. Methods The “Questionnaire on Teaching Evaluation in Public Health Courses”, including teaching attitude, teaching content, teaching methods and teaching effectiveness was designed, and a general investigation was conducted among the clinical medical students of five-year program (840 students) and eight-year program (278 students) in these three aspects to under-stand students' evaluation to the course, who had finished the public health courses, including Preven-tive Medicine, Medical Statistics and Epidemiology (hereinafter referred to as: statistics, epidemiology, prevention) in Sun Yat-sen University. Statistical analysis was made using SPSS 13.0 software. Data analysis methods contain descriptive analysis, T-test, ANOVA, LSD, SNK, hierarchical logistic regres-sion analysis, etc. Results The overall score of teaching evaluation is (4.04±0.60). Differences exist between the evaluation in the five-year medical students and the eight-year medical students. The P values were 0.000 (Medical Statistics), 0.269 (Epidemiology), 0.047 (Preventive Medicine). The com-parison of scores among the four dimensions shows: Teaching effectiveness < Teaching methods β' effectiveness. Conclusions Clinical Medical students' overall evaluation on the public health courses offered by this university was good. Teaching effectiveness and teaching methods still need improvement. Teaching contents are the most influential factor of overall teaching satisfaction, followed by teaching effectiveness.

Objective To recognize and identify the arginase(ARG)gene of Schistosoma japonicum(Sj),and to study its protection potential as a vaccine.Methods The 5'-end of the ARG gene from the Sj cercariae cDNA library was amplified by nested-PCR and the sequence was identified by bioinformatics.The complete coding sequence(CDS)was cloned into pET30a(+)vector,and a recombinant SjARG protein(rSjARG)was expressed,purified and used to raise antibodies.ARG's activity as an enzyme was tested by ornithine-ninhydrin reaction.Western blotting was used to compare the immunologic characteristics of rSjARG with that of the native one in Sj adult worm.Indirect immunofluorescence assay was used to immunolocalize it.For evaluating the protection potential of rSjARG,mice were immunized by the recombinant protein and challenged by cercariae of S.japonicum.Results The CDS length of the SjARG novel gene was identified as 1095bp.rSjARG showed enzyme activity and the same immunologic characteristics with the native arginase in adult worm.SjARG located in the genital organ and gut of both sexes.The worm reduction rate and egg reduction rate in rSjARG group were 55.8% and 48.8% respectively,higher than that of the rSj26GST group(28.6% and 6.89% respectively).Conclusion SjARG gene was identified,which shows a higher protection than the Sj26GST.

After analyzing the correlation coefficient (r) of mid-clavicular liver size (MCL) and mid-sternal liver size (MSL), and the rate of correspond once between palpation and B Ultrasound of spleen, it was found that the "r" of MCL and MSL is 0. 6476 and 0. 5623 respectively, the correspond once rate of spleen is 76. 23%, This result shows that the examiner must master the palpation technique well and B Ultrasound should be used in the screening of schistosomiasis japonica if possible.

Objectve To detect whether the CTP(phosphocholine cytidylyltransferase) gene was expressed in the asexual erythrocytic stages of Plasmodium falciparum (FCC 1/HN )by using the RT - PCR and to construct eukaryotic expression vector of CTP. Method The erythrocytic stage parasites of Plasmodium falciparum were cultured as described by Trager and Jensen. RNA from erythrocytic stage parasite was extracted by using Trizol reagent. The complete genes coding for CTP gene isolates FCCI/HN were amplified by reverse transcriptase -polymerase chain reaction(RT- PCR). CTP gene was cloned into eukaryotic expression vector pcDNA3. Results CTP encoding gene was amplified from the erythrocytic stages of Plasmodiumfalciparum (FCC 1/HN) and eukaryotic expression vector of CTP was constructed. Conclusion CTP gene was expressed in the erythrocytic stages of Plasmodium falciparum (FCC 1/HN) and eukaryotic expression vector of CTP was successfully constructed.