Infectious diseases are characterized as their pathogens.So the detection of pathogen is very important for the diagnosis of infectious diseases.Molecular diagnosis based on polymerase chain reaction (PCR) is playing an important role in the diagnosis,therapy,and prevention for infectious diseases.The concept of quasispecies must be put into consideration for quasispecies are universal for almost every pathogen and important for the diagnosis.Resistance is emerging along with anti-microbial therapy and has comprehensive impaet for treatment of infectious diseases.Diagnosis of resistance will be helpful for seleetion of right drug,and modification of therapy protocol,and reduction of resistance.Genotyping technique is meaningful for individualized therapy for patients with infectious diseases.

Antiviral therapy is important for patients with chronic hepatitis B. Mutation of hepatitis B virus ( HBV ) is closely related to drug resistance of HBV. Immune selection and drug treatment have effects on emergence of drug resistance. Polymerase chain reaction based techniques are major methods for detection of drug resistance of HBV. Regular detection of HBV DNA is the most important method for monitoring drug resistance. Combination therapy of lamivudine plus adefovir is superior to adefovir alone for lamivudine-refractory patients with chronic hepatitis B.

The pathogenesis of viral hepatitis caused by hepatitis B virus (HBV) and hepatitis C virus (HCV) infection has not been fully elucidated. The cloning of new genes which are related to the hepatitis viruses is an important informational resource for the study of pathogenesis of viral hepatitis. The life cycle, including replication and expression of hepatitis viruses, has been controlled by the protein derived from hepatocyte. The protein-protein interaction between the hepatitis virus and hepatocyte exerts significant impact on signal transduction. The gene expression pattern might be also affected by the expression of hepatitis viral proteins, which might be the mechanism underlying the development of chronic hepatitis and hepatocellular carcinoma (HCC). Yeast one hybrid, yeast two hybrid, DNA chips, suppression subtractive hybridization(SSH), phage display, protein purification and DNA cloning techniques were employed in the present study of the pathogenesis of viral hepatitis, including the study of hepatitis viral DNA/RNA-binding protein identification, hepatitis viral protein-binding protein, and target genes of hepatocyte transactivated by hepatitis viral proteins. All these studies will promote the progress in the field of study on pathogenesis and new therapies of viral hepatitis.

Phage display is a technique that combines the expressed protein/peptide on the surface of a bacteriophage and its affinity binding capacity. The pⅢ and pⅧ genes are both suitable target sites for insertion of foreign cDNA fragment. In the early stage of this technique, it was mainly used for screening and identification of single chain antibody(scFv) and/or random peptide. Along with the construction and application of cDNA library for phage display, the application of this technique has been significantly broadened. At present phage display is one of the most important and efficient techniques for the study of protein-protein interaction, and DNA/RNA-binding proteins. Even non-protein small molecule-binding proteins could be defined by this technique. Recent progress has demonstrated that the phage display technique is a powerful tool for the investigation of autoantigen, tumor marker, proteins related to signal transduction, and even regulatory proteins involved in the gene expression of hepatitis viruses.

The pathogenesis of viral hepatitis caused by hepatitis B virus (HBV) and hepatitis C virus (HCV) infection is still not clearly elucidated. Cloning of new genes related to the hepatitis virus proteins transactivation by suppression subtractive hybridization (SSH) and cDNA microarray is an important informational resource for the study of the pathogenesis of viral hepatitis. The C-terminally truncated middle surface protein (MHBst) of HBV, HBxAg, HCV core protein, HCV non-structural protein 3 (NS3), and HCV non-structural protein 5A (NS5A) are among the most important transactivating proteins encoded by hepatitis virus genome. The hepatitis virus proteins transactivate gene expression of hepatocytes by disturbing the normal signal transduction, including NF-?B, STAT3, MAPK, Nur77 and PI3K, etc. Therefore, studies in this field would promote a better understanding of the pathogenesis and might help propose potential therapies for liver diseases caused by chronic hepatitis virus infection.

Objective Chronic hepatitis B virus(HBV) infection is not only a medical problem,but a social and psychiatry problem.The consequence is quiet different for the infected person at different time of life.The final control of HBV infection resulted from steps on antiviral therapy.HB vaccination plays an important role for protection of uninfected persons and changes prevalence of HBV infection in high epidemic area.Not all the HBV infected patients need to be treated immediately,but only for those have active inflammation and fibrosis.Interferon alpha and nucleos(t)ide analogues including lamivudine,adefovir,entecavir and LdT are the first line choice for the treatment of the patients with chronic HBV infection.The final goal of antiviral therapy should be clinical resolution,but not viral,immunological,and histological improvements.The management of CHB is still a problem although many clinical achievements in recent years.

Mutations of hepatitis B virus (HBV) viral genomes are normal biological events and result in the heterogeneity, such as coexistence of viral genotypes and serotypes in infected individuals('quasispecies'). The HBV DNA heterogeneity is ubiquitous all chronic HBV infected patients, and it involves each DNA fragment of both structural and regulatory genes. The process of heterogeneity is continuing,with important biological and clinical implications, playing an important role inthe pathogenesis, drug resistance, and even hepato carcinogenesis in hepatitis patients. The introduction of the conception of quasispecies may contribute to a revolutionary re evaluation of the mutations of HBV DNA.

Medical ethics and ethos is a systematic and psychic engineering for hospital construction,essential requirement for creating a good image of a hospital,establishing a harmonious hospital and building a symphonious physician-patient relationship.This article summarizes the current condition about medical ethics and ethos,investigates how to strengthen the construction of hospital medical ethics and construct a set of effective rules and regulations under the guidance of scientific thinking on development.

Medical ethics construction is a permanent theme in development of medical and health service,which is an important part of harmonious socialist society.By summary and analysis of the current situation and main causes,the author put forward some measures and strategies for strengthening medical ethics construction.Meanwhile,the author suggest the health administration and medical institution should pay more attention to medical ethics construction and build a series of effective regulation and system,then contribute to the construction of a harmonious socialist society.

The pathogenesis of hepatitis C virus (HCV) is different from that of DNA virus and retrovirus. The epitope inducing neutralizing antibody in high variable region 1 (HVR1) is the reason for escape of host immune surveillance, evolution of chronic infection, and also difficulty of producing wide spectrum vaccine. Mimotope selected by using phage display technique is an alternative to solve this problem. The study on the binding protein to non coding region of HCV RNA is helpful to uncover the regulation of replication and translation of HCV genome. A study of the specific receptor of HCV is important to elucidate the mechanism of how HCV enter the hepatocyte. Yeast two hybrid is a useful technique to study the protein protein interactions between HCV and hepatocyte. Suppressive subtraction hybridization is an efficient method for identification of genes of interest transactivated by HCV structural and non structural proteins. All these studies will finally resulted in the full understanding of HCV pathogenesis, and will supply unique opportunity for the development of a new therapy for HCV infection.