Mechanism of the dependence of hepatitis B virus genotype G on co-infection with other genotypes for viral replication.

Hepatitis B virus (HBV) is classified into several genotypes. Genotype G (HBV/G) is characterised by worldwide dispersion, low intragenotypic diversity and a peculiar sequence of the precore and core region (stop codon and 36-nucleotide insertion). As a rule, HBV/G is detected in co-infection with another genotype, most frequently HBV/A2. In a previous in vivo study, viral replication of HBV/G was significantly enhanced by co-infection with HBV/A2. However, the mechanism by which co-infection with HBV/A2 enhances HBV/G replication is not fully understood. In this study, we employed 1.24-fold HBV/A2 clones that selectively expressed each viral protein and revealed that the core protein expressing construct significantly enhanced the replication of HBV/G in Huh7 cells. The introduction of the HBV/A2 core promoter or core protein or both genomic regions into the HBV/G genome showed that both the core promoter and core protein are required for efficient HBV/G replication. The effect of genotype on the interaction between foreign core protein and HBV/G showed that HBV/A2 was the strongest enhancer of HBV/G replication. Furthermore, Western blot analysis of Dane particles isolated from cultures of Huh7 cells co-transfected by HBV/G and a cytomegalovirus (CMV) promoter-driven HBV/A2 core protein expression construct indicated that HBV/G employed HBV/A2 core protein during particle assembly. In conclusion, HBV/G could take advantage of core proteins from other genotypes during co-infection to replicate efficiently and to effectively package HBV DNA into virions.

Determination of hepatitis B virus genotype G by polymerase chain reaction with hemi-nested primers.

Hepatitis B virus (HBV) has been classified into six genotypes designated A-F by sequence divergence in the entire genome exceeding 8%. Very recently, the seventh genotype was reported and named genotype G. HBV genotype G is distinct from genomes of the other six genotypes in that it possesses an insertion of 36 nucleotides in the core gene, and has been found so far in France and the United States. A method for determining HBV genotype G was developed by polymerase chain reaction (PCR) with primers deduced from the 36-nucleotide (nt) insertion in five isolates of HBV genotype G the sequences of which have been deposited in DNA databases. The validity of this method, for specifically detecting HBV genotype G, was verified on a panel consisting of 142 HBV isolates of six major genotypes and four of genotype G. A total of 540 sera containing HBV in Japan covering symptom free carriers and patients with a spectrum of chronic liver disease were tested by this method, but not a single HBV genotype G sample was found. A possible method for serological determination of hepatitis B surface antigen of genotype G is suggested, without amplification or sequencing nucleotides, which would expand epidemiological and clinical researches on HBV genotype G.

Hepatitis B virus infection among residents of a nursing home for the elderly: seroepidemiological study and molecular evolutionary analysis.

A seroepidemiological study of HBV infection was carried out to investigate the seroprevalence of hepatitis B surface antigen (HBsAg) and the transmission routes of hepatitis B virus (HBV) infection among residents of a nursing home for the elderly. HBV serum markers were examined in 119 residents and 71 healthcare workers in the institution, as also in 1330 healthy subjects from the same geographical area, as the control group. HBsAg was detected in 6 (5%), 0 and 20 (1.5%) residents, healthcare workers and healthy subjects, respectively. Four residents (A-D) who had HBV-DNA in the serum were studied by molecular evolutionary analysis. The strains derived from residents A, B and D were clustered together within a close range of evolutionary distances. Residents B and D, who were not positive for HBsAg at the time of admission to the institution, subsequently became HBsAg-positive asymptomatic carriers. These results suggested intrainstitutional transmission of HBV in the nursing home for the elderly, and confirmed that the source of transmission of HBV to residents B and D was resident A who was positive for HBsAg. Residents in a nursing home for the elderly should be considered as being a high-risk group for HBV infection, and vaccination against HBV of these groups is recommended.

Molecular evolutionary analysis of the complete nucleotide sequence of hepatitis B virus (HBV) in a case of HBV infection acquired through a needlestick accident.

To elucidate needlestick transmission of hepatitis B virus (HBV), strains isolated from 1 physician who acquired HBV infection through a needlestick accident and 3 patients with chronic hepatitis B (donor patients A, B, and C) were tested using molecular evolutionary analysis based on full-length HBV genomic sequences. Nucleotide sequences of these isolates were aligned with 55 previously reported full-length genomic sequences. Genetic distances were estimated using the 6-parameter method, and phylogenetic trees were constructed using the neighbor-joining method. Strains isolated from patient A and the recipient pair were clustered within a closer range of evolutionary distances than were strains recovered from the recipient pair and patients B and C. Furthermore, strains from patient A and the recipient were also clustered on the S gene sequences of HBV. These results demonstrated that patient A alone was the source of direct transmission to the recipient. This approach can be used to investigate the transmission route of HBV.

Lack of association between TTV viral load and aminotransferase levels in patients with hepatitis C or non-B-C.

TT virus (TTV) is a newly identified un-enveloped single-stranded DNA virus. Although TTV was initially thought to be a new hepatitis virus, it is still unclear whether it causes hepatitis. To clarify the natural history and pathogenesis of TTV infection, serial serum samples from patients with chronic hepatitis were analysed. TTV DNA was quantified by real-time detection polymerase chain reaction assay (RTD-PCR), which was adapted for TTV. Five patients with chronic hepatitis, 4 with hepatitis C and 1 with non-B-C, were studied. The study period ranged from 9 to 50 months. In 3 patients there were frequent increases in TTV DNA titres, but no concomitant elevation of the aminotransferase (ALT) levels. In 2 patients who were treated with interferon, the changes in TTV titres were not synchronized with those of the ALT levels. Thus, in cases of chronic hepatitis, no correlation was observed between the serum TTV DNA titres and the ALT levels.

Development of a TT virus DNA quantification system using real-time detection PCR.

Although TT virus (TTV) was isolated from a cryptogenic posttransfusion hepatitis patient, its pathogenic role remains unclear. It has been reported that the majority of the healthy population is infected with TTV. To elucidate the differences between TTV infection in patients with liver diseases and TTV infection in the healthy population, a quantification system was developed. TTV DNA was quantified by a real-time detection PCR (RTD-PCR) assay on an ABI Prism 7700 sequence detector. With this system, TTV DNA was quantified in 78 hepatitis C virus (HCV)-infected patients (63 with elevated serum alanine aminotransferase [ALT] levels and 15 with normal ALT levels) and in 70 voluntary blood donors (BDs). The quantification range was 2.08 to 7.35 log copies/ml. The intra-assay and interassay coefficients of variation were 0.37 to 6.33% and 0.60 to 7.07%, respectively. The mean serum TTV DNA levels in the HCV-infected patients with both elevated and normal ALT levels and BDs were 3.69 +/- 0.89, 3.45 +/- 0.76, and 3.45 +/- 0.67 log copies/ml, respectively. Comparison of the serum TTV DNA levels among the HCV-infected patients revealed that they were not related to the serum ALT and HCV core protein levels or to the histopathological score on liver biopsy. This study showed that (i) the RTD-PCR assay for the detection of TTV was accurate and had a high degree of sensitivity, (ii) the mean serum TTV DNA level was similar among HCV-infected patients, irrespective of their ALT level, and also among BDs, and (iii) a high serum TTV DNA level does not affect the serum ALT and HCV levels or liver damage in HCV-infected patients.

High prevalance of TT virus infection in Japanese patients with liver diseases and in blood donors.

BACKGROUND/AIMS: Although a novel DNA virus, TT virus (TTV), has been isolated from a patient with cryptogenic post-transfusion hepatitis, its pathogenic role remains unclear. To elucidate its prevalence and clinical impact in patients with liver diseases, the presence of TTV DNA was assessed in patients with liver diseases and blood donors (BDs) in Japan using two primer sets, one conventional and the other new and highly sensitive. METHODS: We studied 261 samples, 72 with chronic hepatitis associated hepatitis C virus (HCV-CH), 57 with hepatocellular carcinoma associated HCV (HCV-HCC), 12 with HCC without either HCV or hepatitis B virus (NBNC-HCC), and 120 of BDs. RESULTS: Using two primer sets, TTV DNA was detected in 68 (94.4%), 53 (93.0%), 12 (100%), and 98 (81.7%) HCV-CH, HCV-HCC, NBNC-HCC, and BDs, respectively. The prevalence was not significantly different between HCV-CH and HCV-HCC, or between HCV-HCC and NBNC-HCC. Comparison between patients with and without TTV revealed no significant differences in backgrounds or biochemical findings. Histopathological findings in patients with HCV-CH, and number, maximum diameter, and histological differentiation of HCC also did not demonstrate any relation to TTV infection. TTV strains can be divided into five groups using phylogenetic analysis, but no disease-specific group appears to exist. CONCLUSIONS: Our data suggest that: 1) TTV is very prevalent among patients with liver diseases and even among BDs in Japan, 2) TTV infection does not impact on liver damage with HCV infection, and 3) TTV infection also does not affect the development or progression of HCC.

Cystic lymphangioma of the gall-bladder: a case report.

Intra-abdominal cystic lymphangiomas are rare lesions that can be difficult to diagnose. We present a report of a patient with a giant multilocular cystic lesion in the abdomen. Ultrasonography and computed tomography scans of the abdomen revealed that the cyst had originated in the gall-bladder fossa. There was some calcification and thickening of the cyst wall. Endoscopic retrograde cholangiopancreatography demonstrated a medially deviated common bile duct, an elongated cystic duct and an inferior compressed gallbladder. There was no apparent communication between the cyst and the biliary tract; however, an abdominal angiogram revealed that the lesion was supplied by a branch of the cystic artery. Histological findings obtained intra-operatively were consistent with a cystic lymphangioma. Its characteristic histology was observed in the subserous layer of the gall-bladder. This case is a rare instance of a cystic lymphangioma originating in the gall-bladder.