Usually anti-HBc IgM can be detected and HBV DNA is present. the comparison of assays for quantitative measurement of HBV DNA. Table 1 Comparison of quantitative methods for HBV DNA Aminophylline thead th valign=”middle” align=”left” scope=”col” rowspan=”1″ colspan=”1″ Methods /th th valign=”middle” align=”left” scope=”col” rowspan=”1″ colspan=”1″ Commercial assay name /th th valign=”middle” align=”left” scope=”col” rowspan=”1″ colspan=”1″ Manufacturer /th th valign=”middle” align=”center” scope=”col” rowspan=”1″ colspan=”1″ Measurable range (IU/mL) /th th valign=”middle” align=”center” scope=”col” rowspan=”1″ colspan=”1″ Limit of detection (IU/mL) (using WHO HBV standard) /th /thead Semi-automated qPCRCOBAS AmpliPrep/COBAS TaqMan HBV Test v2.0Roche Molecular System, California, United States20C1.7 10720Semi-automated real-time PCRCOBAS TaqMan HBV Aminophylline Test for use with high pure systemRoche Molecular System, California, United States29C1.11076Automated real-time PCRAbbott RealTime HBVAbbott Diagnostic, Chicago, United States10C110910Branched DNAVERSANT HBV 3.0 AssaySiemens Healthcare, United States2,000C11082,000 Open in a separate window WHO, World Health Organization; HBV, hepatitis B virus; PCR, polymerase chain reaction; qPCR, quantitative PCR. HBV genotyping HBV has a high genetic heterogeneity because it reproduces via a reverse transcriptase that has insufficient proofreading capability. According to the sequence divergence, HBV can be divided into ten genotypes, labelled ACJ: they have distinct geographic distribution (24). Genotype B and C are restricted to Oceania and Asia, whereas genotype A and D are omnipresent but most common in Africa and Europe (25). Genotype I is unusual and can be observed in Vietnam, Laos, India and China, while genotype J has been reported in Japan and Ryukyu (26,27). Other genotypes such as E, F, G, and H are also occasionally found in Asia. Evidences increasingly suggest that the HBV genotyping is significant to predict HBV disease progression and determine appropriate antiviral therapy. Acute infection with genotypes A and D leads to higher rate of chronicity than genotypes B and C (28-30). Genotype C generally is considered as a risk factor for perinatal infection (31) and related to severe liver disease, including cirrhosis and HCC (32-34). In the interferon therapy, patients with genotypes A and Aminophylline B have better treatment response than genotypes C and D (35). Recent studies reported that patients infected with genotype B or C had a lower opportunity to gain serological response to tenofovir (36,37). HBV genotyping can be confirmed using diverse methods: reverse hybridization, genotype-specific PCR assays, real-time PCR, restriction fragment-length polymorphism, sequence analysis, microarray (DNAChip) and fluorescence polarization assay (38). The characteristics of variable HBV genotyping methods are presented on em Table 2 /em . Table 2 Methods of HBV genotyping thead th valign=”middle” align=”left” scope=”col” rowspan=”1″ colspan=”1″ Methods /th th valign=”middle” align=”left” scope=”col” rowspan=”1″ colspan=”1″ Advantages /th th valign=”middle” align=”left” scope=”col” rowspan=”1″ colspan=”1″ Disadvantages /th th valign=”middle” align=”center” scope=”col” rowspan=”1″ colspan=”1″ References /th /thead RFLPEasily done, low cost, simple, rapidLow sensitivity for typing samples with low HBV(19,39)Reverse hybridizationHigh sensitivity, automated systemsRelatively high cost(40,41)Genotype specific PCRHigh sensitivity, automated systems, easy to perform, suitable for detecting mixed genotype infectionsHigh cost(41)Sequence analysisGold standard method for genotyping, identification of patients infected with recombinant genotypesTime consuming, technically demanded(41) Open in a separate window HBV, hepatitis B virus; RFLP, restriction fragment length polypmorphism; PCR, polymerase chain reaction. Diagnosis of hepatitis B infection Acute hepatitis B is a clinical diagnosis identified by the detection of HBsAg, symptoms, high serum aminotransferases. Usually anti-HBc IgM can be detected and HBV DNA is present. HBeAg can also be identified in most acute phase of infections, but has little clinical importance. The diagnosis of chronic infection is based on the persistence of HBsAg for more than 6 months. Patients with chronic HBV infection are commonly diagnosed by laboratory means but not by clinical presentations. Past HBV infection is defined by the coexistence of anti-HBs and IgG anti-HBc. Occult HBV infection is defined by persistence of low level of intrahepatic HBV DNA without detectable HBsAg (42,43). It is a serological situation defined by the presence of isolated anti-HBc with the absence NR1C3 of HBsAg and anti-HBs antibody (44,45). The detection of HBV DNA in the liver is the gold standard of diagnosis for occult HBV infection, since cccDNA remains in the hepatocytes and HBV DNA is occasionally identified in the liver but not in the serum. However, gaining hepatic HBV Aminophylline DNA is difficult in clinical setting since the procedure is invasive. Real-time PCR for serum HBV DNA detection have been shown with adequate sensitivity to identify occult HBV infection in many cases; thus, HBV DNA.