Characterization and biological properties of a hepatitis B virus isolated from a patient without hepatitis B virus serologic markers

Diverse Virus and Host-Dependent Mechanisms Influence the Systemic and Intrahepatic Immune Responses in the Woodchuck Model of Hepatitis B

Woodchuck infected with woodchuck hepatitis virus (WHV) represents the pathogenically nearest model of hepatitis B and associated hepatocellular carcinoma (HCC). This naturally occurring animal model also is highly valuable for development and preclinical evaluation of new anti-HBV agents and immunotherapies against chronic hepatitis (CH) B and HCC. Studies in this system uncovered a number of molecular and immunological processes which contribute or likely contribute to the immunopathogenesis of liver disease and modulation of the systemic and intrahepatic innate and adaptive immune responses during hepadnaviral infection. Among them, inhibition of presentation of the class I major histocompatibility complex on chronically infected hepatocytes and a role of WHV envelope proteins in this process, as well as augmented hepatocyte cytotoxicity mediated by constitutively expressed components of CD95 (Fas) ligand- and perforin-dependent pathways, capable of eliminating cells brought to contact with hepatocyte surface, including activated T lymphocytes, were uncovered. Other findings pointed to a role of autoimmune response against hepatocyte asialoglycoprotein receptor in augmenting severity of liver damage in hepadnaviral CH. It was also documented that WHV in the first few hours activates intrahepatic innate immunity that transiently decreases hepatic virus load. However, this activation is not translated in a timely manner to induction of virus-specific T cell response which appears to be hindered by defective activation of antigen presenting cells and presentation of viral epitopes to T cells. The early WHV infection also induces generalized polyclonal activation of T cells that precedes emergence of virus-specific T lymphocyte reactivity. The combination of these mechanisms hinder recognition of virus allowing its dissemination in the initial, asymptomatic stages of infection before adaptive cellular response became apparent. This review will highlight a range of diverse mechanisms uncovered in the woodchuck model which affect effectiveness of the anti-viral systemic and intrahepatic immune responses, and modify liver disease outcomes. Further exploration of these and other mechanisms, either already discovered or yet unknown, and their interactions should bring more comprehensive understanding of HBV pathogenesis and help to identify novel targets for therapeutic and preventive interventions. The woodchuck model is uniquely positioned to further contribute to these advances.

Asymptomatic Hepadnaviral Persistence and Its Consequences in the Woodchuck Model of Occult Hepatitis B Virus Infection

Woodchuck hepatitis virus (WHV) is molecularly and pathogenically closely related to hepatitis B virus (HBV). Both viruses display tropism towards hepatocytes and cells of the immune system and cause similar liver pathology, where acute hepatitis can progress to chronic hepatitis and to hepatocellular carcinoma (HCC). Two forms of occult hepadnaviral persistence were identified in the woodchuck-WHV model: secondary occult infection (SOI) and primary occult infection (POI). SOI occurs after resolution of a serologically apparent infection with hepatitis or after subclinical serologically evident virus exposure. POI is caused by small amounts of virus and progresses without serological infection markers, but the virus genome and its replication are detectable in the immune system and with time in the liver. SOI can be accompanied by minimal hepatitis, while the hallmark of POI is normal liver morphology. Nonetheless, HCC develops in about 20% of animals with SOI or POI within 3 to 5 years. The virus persists throughout the lifespan in both SOI and POI at serum levels rarely greater than 100 copies/mL, causes hepatitis and HCC when concentrated and administered to virus-naïve woodchucks. SOI is accompanied by virus-specific T and B cell immune responses, while only virus-specific T cells are detected in POI. SOI coincides with protection against reinfection, while POI does not and hepatitis develops after challenge with liver pathogenic doses >1000 virions. Both SOI and POI are associated with virus DNA integration into the liver and the immune system genomes. Overall, SOI and POI are two distinct forms of silent hepadnaviral persistence that share common characteristics. Here, we review findings from the woodchuck model and discuss the relevant observations made in human occult HBV infection (OBI).

Viral hepatitis in hemodialysis: An update

Hepatitis outbreaks in hemodialysis (HD) patients and staff were reported in the late 1960s, and a number of hepatotropic viruses transmitted by blood and other body fluids have been identified. Hepatitis B virus (HBV) was the first significant hepatotropic virus to be identified in HD centers. HBV infection has been effectively controlled by active vaccination, screening of blood donors, the use of erythropoietin and segregation of HBV carriers. Hepatitis delta virus is a defective virus that can only infect HBV-positive individuals. Hepatitis C virus (HCV) is the most significant cause of non-A, non-B hepatitis and is mainly transmitted by blood transfusion. The introduction in 1990 of routine screening of blood donors for HCV contributed significantly to the control of HCV transmission. An effective HCV vaccine remains an unsolved challenge; however, pegylation of interferon-alfa has made it possible to treat HCV-positive dialysis patients. Unexplained sporadic outbreaks of hepatitis by the mid-1990s prompted the discovery of hepatitis G virus, hepatitis GB virus C and the TT virus. The vigilant observation of guidelines on universal precaution and regular virologic testing are the cornerstones of the effective control of chronic hepatitis in the setting of HD. Major recent advances in the viral diagnosis technology and the development of new oral, direct-acting antiviral agents allow early diagnosis and better therapeutic response. The current update will review the recent developments, controversies and new treatment of viral hepatitis in HD patients.

Occult hepatitis B virus infection in hemodialysis patients: a concept for consideration

Hemodialysis patients potentially have an increased risk of infection with parenterally transmitted viral agents due to an impaired host immune response and multiple transfusion requirements. Viral hepatitis is considered as a problem for hemodialysis patients because 1.9% of all deaths among this population are related to the consequence of viral hepatitis. Hepatitis B virus (HBV) is one of the most important causes of transmitted infections by the parenteral route in hemodialysis patients. Occult HBV infection is characterized by presence of HBV infection without detectable hepatitis B surface antigen (HBsAg), which harbors potential risk of HBV transmission through hemodialysis. There are conflicting reports on the prevalence of occult HBV infection (OBI) in hemodialysis patients. Considering the importance of occult HBV infection in hemodialysis patients and the growing evidence on this subject, the purpose of this review is to provide comprehensive information on OBI prevalence in hemodialysis patients and highlight the most important points in this issue.

Occult hepatitis B virus infection in hemodialysis patients with isolated hepatitis B core antibody: a multicenter study

Occult hepatitis B virus (HBV) infection is characterized by presence of HBV infection with undetectable hepatitis B surface antigen (HBsAg). Occult HBV infection harbors potential risk of HBV transmission through hemodialysis (HD). The aim of this study was to assess the occult HBV infection in hemodialysis patients with isolated hepatitis B core antibody (anti-HBc). A total of 289 HD patients from five dialysis units in Tehran, Iran, were included in this study. Hepatitis B surface antigen (HBsAg), Hepatitis B surface antibody (anti-HBs), anti-HBc, Hepatitis C antibody (anti-HCV), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were tested in all subjects. The presence of HBV-DNA was determined quantitatively in plasma samples of HD patients with isolated anti-HBc (HBsAg negative, anti-HBs negative and anti-HBc positive) by real-time PCR using the artus HBV RG PCR kit on the Rotor-Gene 3000 real-time thermal cycler. Of 289 patients enrolled in this study, 18 subjects (6.2%, 95% confidence interval (CI), 3.5%-8.9%) had isolated anti-HBc. HBV-DNA was detectable in 9 of 18 patients (50%, 95% CI, 27%-73%) who had isolated anti-HBc. Plasma HBV-DNA load was less than 50 IU/ml in all of these patients. Our study showed that detection of isolated anti-HBc could reflect unrecognized occult HBV infection in HD patients. The majority of these infections are associated with low viral loads.

Occult hepatitis B virus infection in ART-naive HIV-infected patients seen at a tertiary care centre in north India

BACKGROUND

Co-infections of hepatitis B and C viruses are frequent with HIV due to shared routes of transmission. In most of the tertiary care health settings, HIV reactive patients are routinely tested for HBsAg and anti-HCV antibodies to rule out these co-infections. However, using the routine serological markers one can only detect active HBV infection while the occult HBV infection may be missed. There is insufficient data from India on HIV-HBV co-infection and even scarce on occult HBV infection in this group.

METHODS

We estimated the burden of HBV infection in patients who were tested positive for HIV at a tertiary care centre in north India. We also attempted to determine the prevalence and clinical characteristics of occult HBV infection among these treatment-naïve patients and compare their demographic features with other HIV patients. During a period of 6 years between January 2002 to December 2007, 837 HIV positive patients (631 males and 206 females (M: F :: 3.06:1) were tested for serological markers of HBV (HBsAg) and HCV (anti-HCV antibodies) infections in our laboratory. For comparison 1000 apparently healthy, HIV-negative organ donors were also included in the study. Data on demographics, sexual behaviour, medical history, laboratory tests including the serum ALT and CD4 count of these patients were recorded. A sub-group of 53 HBsAg negative samples from HIV positive patients were assessed for anti-HBs, anti-HBc total (IgG+IgM) and HBV-DNA using a highly sensitive qualitative PCR and analysed retrospectively.

RESULTS

Overall, 7.28% of HIV positive patients showed presence of HBsAg as compared to 1.4% in the HIV negative control group. The prevalence of HBsAg was higher (8.55%) in males than females (3.39%). The study revealed that occult HBV infection with detectable HBV-DNA was prevalent in 24.5% of patients positive for anti-HBc antibodies; being 45.5% in HBsAg negative patients. Most importantly the occult infection was seen in 20.7% patients who were positive for anti-HBs antibodies. However, in none of the seronegative patient HBV-DNA was detected. Five of the nine HBV-DNA positive (55.6%) patients showed raised alanine aminotransferase levels and 66.7% had CD4+ T cell counts below 200 cells/cumm.

CONCLUSIONS

High prevalence of HIV-HBV co-infection was found in our patients. A sizeable number of co-infected patients remain undiagnosed, if only conventional serological markers are used. Presence of anti-HBs antibodies was not a reliable surrogate marker to rule out occult HBV infection. The most reliable method to diagnose occult HBV co-infection in HIV seropositive patients is the detection of HBV-DNA.

Surface gene mutations of hepatitis B virus among high-risk patients with occult hepatitis B virus infection

Surface gene mutants of hepatitis B virus (HBV) have been reported in a variety of patient groups. Because of limited data regarding these mutations in patients with occult HBV infections; we aimed to determine these mutations among high-risk patients with occult HBV infection. The presence of HBV-DNA was determined in patients with isolated anti-HBc by real-time polymerase chain reaction (PCR). Then, surface gene region was amplified by nested PCR and mutations were analyzed after sequencing. The mutations that resulted in nonfunctional hepatitis B surface antigen (HBsAg) were insertion of single nucleotide in 2 cases, which causes frameshift and single-nucleotide replacement, and premature stop codons at Leu15 and Gly10 in the other 2 cases. Amino acid substitution at amino acid position 207(S207N) was found in the other isolates. Our study suggested that "a" region mutations did not play a major role in HBsAg detection, and other genetic and nongenetic factors may be responsible for failure to detect HBsAg by routine laboratory tests.

Lack of occult hepatitis B virus infection among blood donors with isolated hepatitis B core antibody living in an HBV low prevalence region of Iran

BACKGROUND

Occult hepatitis B virus (HBV) infection in blood donors is considered a potential threat for the safety of the blood supply, however conclusive studies on this issue are lacking. The aim of this study was to assess the occult HBV infection in blood donors with isolated hepatitis B core antibody (anti-HBc) living in the city of Arak, in the Central Province of Iran, as a low prevalence region for HBV.

METHODS

A total of 531 voluntary blood donors in Arak, Iran were included in this study. Hepatitis B surface antigen (HBsAg), hepatitis B surface antibody (anti-HBs), anti-HBc, and hepatitis C antibody (anti-HCV) were tested in all subjects. The presence of HBV-DNA was determined quantitatively in plasma samples of cases with isolated anti-HBc (HBsAg-negative, anti-HBs-negative, and anti-HBc-positive) by real-time PCR using the artus HBV RG PCR kit on the Rotor-Gene 3000 real-time thermal cycler.

RESULTS

Of 531 subjects enrolled in this study, 11 (2.1%, 95% confidence interval 0.8-3.2%) had isolated anti-HBc. HBV-DNA was not detected in any of the cases with isolated anti-HBc.

CONCLUSIONS

Our study showed that all the blood donors with isolated anti-HBc were negative for HBV-DNA, and occult HBV infection did not occur in the blood donors of this low prevalence region for HBV infection.

Hepatitis B: the virus and disease

Hepatitis B virus (HBV) infects more than 300 million people worldwide and is a common cause of liver disease and liver cancer. HBV, a member of the Hepadnaviridae family, is a small DNA virus with unusual features similar to retroviruses. HBV replicates through an RNA intermediate and can integrate into the host genome. The unique features of the HBV replication cycle confer a distinct ability of the virus to persist in infected cells. Virological and serological assays have been developed for diagnosis of various forms of HBV-associated disease and for treatment of chronic hepatitis B infection. HBV infection leads to a wide spectrum of liver disease ranging from acute (including fulminant hepatic failure) to chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Acute HBV infection can be either asymptomatic or present with symptomatic acute hepatitis. Most adults infected with the virus recover, but 5%-10% are unable to clear the virus and become chronically infected. Many chronically infected persons have mild liver disease with little or no long-term morbidity or mortality. Other individuals with chronic HBV infection develop active disease, which can progress to cirrhosis and liver cancer. These patients require careful monitoring and warrant therapeutic intervention. Extrahepatic manifestations of HBV infection are rare but can be difficult to diagnose and manage. The challenges in the area of HBV-associated disease are the lack of knowledge in predicting outcome and progression of HBV infection and an unmet need to understand the molecular, cellular, immunological, and genetic basis of various disease manifestations associated with HBV infection.

Management of hepatitis B: summary of a clinical research workshop

Chronic hepatitis B is caused by persistent infection with the hepatitis B virus (HBV), a unique DNA virus that replicates through an RNA intermediate produced from a stable covalently closed circular DNA molecule. Viral persistence appears to be due to inadequate innate and adaptive immune responses. Chronic infection has a variable course after several decades resulting in cirrhosis in up to one-third of patients and liver cancer in a proportion of those with cirrhosis. Sensitive assays for HBV DNA levels in serum have been developed that provide important insights into pathogenesis and natural history. Therapy of hepatitis B is evolving. Peginterferon induces long-term remissions in disease in one-third of patients with typical hepatitis B e antigen (HBeAg) positive chronic hepatitis B, but a lesser proportion of those without HBeAg. Several oral nucleoside analogues with activity against HBV have been shown to be effective in suppressing viral levels and improving biochemical and histological features of disease in a high proportion of patients with and without HBeAg, at least in the short term. What is uncertain is which agent or combination of agents is most effective, how long therapy should last, and which criteria should be used to start, continue, switch or stop therapy. Long-term therapy with nucleoside analogues may be the most appropriate approach to treatment, but the expense and lack of data on long-term safety and efficacy make recommendations difficult. Clearly, many basic and clinical research challenges remain in defining optimal means of management of chronic hepatitis B.

Patterns of hepatitis B virus infection in Brazilian human immunodeficiency virus infected patients: high prevalence of occult infection and low frequency of lamivudine resistant mutations

Hepatitis B virus (HBV) molecular profiles were determined for 44 patients who were infected with human immunodeficiency virus (HIV) type 1 and had antibodies to the hepatitis B core antigen (anti-HBc), with and without other HBV serological markers. In this population, 70% of the patients were under lamivudine treatment as a component of antiretroviral therapy. HBV DNA was detected in 14 (32%) patients. Eight out of 12 (67%) HBsAg positive samples, 3/10 (30%) anti-HBc only samples, and 3/22 (14%) anti-HBs positive samples were HBV DNA positive. HBV DNA loads, measured by real time polymerase chain reaction, were much higher in the HBsAg positive patients (mean, 2.5 x 10(9) copies/ml) than in the negative ones (HBV occult infection; mean, 2.7 x 10(5) copies/ml). Nine out of the 14 HBV DNA positive patients were under lamivudine treatment. Lamivudine resistant mutations in the polymerase gene were detected in only three patients, all of them belonging to the subgroup of five HBsAg positive, HBV DNA positive patients. A low mean HBV load (2.7 x 10(5) copies/ml) and an absence of lamivudine resistant mutations were observed among the cases of HBV occult infection.

Fibrosis progression in chronic hepatitis C patients with occult hepatitis B co-infection

Occult hepatitis B virus (HBV) infection in individuals without hepatitis B surface antigen (HBsAg) can be identified in hepatitis C virus (HCV) infected patients. However, its role in fibrosis progression remains uncertain. This retrospective study compared the fibrosis progression (defined as fibrosis progression by at least one stage) and progression to severe fibrosis (fibrosis stage 3 or 4) in HCV patients with occult HBV infection. Occult HBV infection was diagnosed by the detection of HBV DNA in the serum of 74 consecutive anti-HCV positive patients by PCR. Thirty-one patients (41.9%) had occult HBV infection. All 74 patients had a median of 2 (range 2-3) liver biopsies. The median time between the first and last liver biopsy was 57.7 (range 15.0-132.8) months. Eleven of the 31 patients with occult HBV infection compared with 12 of the 43 patients without occult HBV infection had fibrosis progression (35.5% versus 27.9%, respectively, p=0.608). Six of the 31 patients with occult HBV infection compared with 8 of the 43 patients without occult HBV infection developed severe fibrosis (19.4% versus 18.6%, respectively, p=0.946). In conclusion, chronic HCV patients with occult HBV co-infection does not seem to progress more than patients without occult HBV infection. However, more large-scale studies are needed before a definite conclusion can be obtained.

Virological significance of low-level hepatitis B virus infection in patients with hepatitis C virus associated liver disease

The clinical and virological significance of low-level viremia by hepatitis B virus (HBV) in hepatitis C virus (HCV)-infected patients remains unclear. HBV-DNA and HCV-RNA were, therefore, quantitatively analyzed in livers and sera from co-infected patients. HBV-DNA and HCV-RNA were quantitated using real-time detection of polymerase chain reaction (RTD-PCR), based on Taq-Man chemistry, in 220 non-HCV-infected healthy volunteers and 93 HCV-infected patients without detectable HBsAg. Serum HBV-DNA was detected in 4 (1.8%) of 220 non-HCV-infected healthy volunteers and 32 (34.4%) of 93 HCV-infected patients without detectable HBsAg. HCV-infected patients displayed higher frequency of HBV infection than healthy volunteers (P < 0.0001). Hepatocellular carcinoma (HCC) was more frequent among co-infected patients than among HCV mono-infected patients (P < 0.001). However, quantities of HBV-DNA in sera from co-infected patients were very low (8-19,000 copies/ml). HBV-DNA was detected in liver tissue from co-infected patients at 2-20 copies per 100 hepatocytes, accounting for 1/1,000 to 1/10,000 of HBsAg positive patients. In livers of patients with HCC and HCV or HBV mono-infection, the viruses existed predominantly in non-cancerous tissue, with levels 10- to 1,000-fold and 1- to 100-fold higher than in cancerous tissue, respectively. In contrast, patients co-infected with HCV and HBV displayed decreased HBV levels in non-cancerous tissue, but no change in cancerous tissue. These results indicate that low-level HBV infection exists in HCV-infected patients. HCC was more common among HCV/HBV co-infected patients than among HCV mono-infected patients. HCV might initiate hepatocarcinogenesis, but does not necessarily determine progression to HCC.

Low doses of hepadnavirus induce infection of the lymphatic system that does not engage the liver

Woodchuck hepatitis virus (WHV), which is closely related to human hepatitis B virus and is considered to be principally hepatotropic, invades the host's lymphatic system and persists in lymphoid cells independently of whether the infection is symptomatic and serologically evident or concealed. In this study, we show, with the woodchuck model of hepatitis B, that hepadnavirus can establish an infection that engages the lymphatic system, but not the liver, and persists in the absence of virus serological markers, including antiviral antibodies. This primary occult infection is caused by wild-type virus invading the host at a quantity usually not greater than 10(3) virions. It is characterized by trace virus replication progressing in lymphatic organs and peripheral lymphoid cells that, with time, may also spread to the liver. The infection is transmissible to virus-naive hosts as an asymptomatic, indefinitely long, occult carriage of small amounts of biologically competent virus. In contrast to residual silent WHV persistence, which normally endures after the resolution of viral hepatitis and involves the liver, primary occult infection restricted to the lymphatic system does not protect against reinfection with a large, liver-pathogenic WHV dose; however, the occult infection is associated with a swift recovery from hepatitis caused by the superinfection. Our study documents that the lymphatic system is the primary target of WHV infection when small quantities of virions invade a susceptible host.

Long-term histologic and virologic outcomes of acute self-limited hepatitis B

The long-term impact of acute self-limited hepatitis B on the liver is unknown. Fourteen patients were recalled at a median of 4.2 years (range, 1.8-9.5 years) after the onset of acute hepatitis B. All showed clinical and serologic recovery with circulating hepatitis B surface antigen (HBsAg) clearance. Antibody to HBsAg (anti-HBs) had developed in 12 patients. Nine underwent liver biopsies at a median of 7.2 years, and histologic findings were evaluated using Ishak scores. Serum samples and frozen liver tissue were subjected to real-time detection polymerase chain reaction (PCR) to quantify the surface and X regions of the hepatitis B virus (HBV) genome and qualitative PCR to detect the covalently closed circular (ccc) HBV DNA replicative intermediate. Three patients had low levels of circulating HBV DNA up to 8.9 years after the onset, whereas both HBV DNA surface and X regions were found in the liver of all 9 patients examined, including 7 negative for serum HBV DNA. Liver viral loads assessed by the 2 regions showed a significant correlation (r = 0.946; P =.008), and all patients tested positive for ccc HBV DNA. Liver fibrosis and mild inflammation persisted in 8 patients. The fibrosis stage had relation to peak serum HBV DNA in the acute phase (P =.046) but not to liver viral loads in the late convalescent phase. In conclusion, occult HBV infection persists in the liver and is accompanied by abnormal liver histology for a decade after complete clinical recovery from acute self-limited hepatitis B.

Frequent occult hepatitis B virus infection in patients infected with human immunodeficiency virus type 1

The presence of hepatitis B virus (HBV) serological markers was investigated in 170 patients (137 male, 33 female) infected with human immunodeficiency virus (HIV) type 1. Antibodies to the hepatitis B core antigen (anti-HBc antibodies) were detected in 115 (68%) patients. Of these 115, 14 (12%) were hepatitis B surface antigen (HBsAg) positive, 60 (52%) presented anti-HBs antibodies, and 41 (35%) were anti-HBc positive only. All 115 of the anti-HBc positive samples were tested for HBV DNA by using two polymerase chain reaction (PCR) assays that amplify the core and pre-S regions of the HBV genome, respectively. HBV DNA was detected in 23 samples: 7 of 14 (50%) HBsAg-positive samples, 12 of 60 (20%) anti-HBs-positive samples, and 4 of 41 (10%) samples positive for anti-HBc only. Six samples (all HBsAg positive) were positive in both PCR assays and 17 samples were HBV DNA positive in only one assay. The mean viral load in HBsAg-positive patients was higher than that observed in HBsAg-negative patients. A number of patients were receiving treatment with lamivudine, a drug that interferes with both HBV and HIV replication. However, neither the rate of HBV DNA positivity nor HBV load was significantly different between patients treated with lamivudine and those not treated with this drug.

Detection of hepatitis B virus in seropositive and seronegative patients with chronic liver disease using DNA amplification by PCR

BACKGROUND

The aim of this study was to detect DNA of hepatitis B virus (HBV) for reliable diagnosis of HBV infection in sera by means of a validated polymerase chain reaction (PCR) using a 5' oligonucleotide (primer) previously described and a 3' primer designed by our investigation group.

METHODS

Sera samples collected from patients with chronic liver disease (CLD) related to HBV infection and negative to hepatitis C virus (HCV) infection were analyzed. Patients were both positive and negative to HBV by serum markers detected by ELISA immunoassay. A 146-base pair (bp) fragment was amplified from highly conserved precore-core region. This procedure enabled us to search for DNA HBV-positive cases.

RESULTS

Viral replicative state in negative hepatitis B e antigen (HBeAg) (15.7%) cases was verified by PCR technique. This detected infection by HBV in 100% of immunoassay-positive samples. Additionally, sequences of expected size in patients bearing atypical markers in their sera (7.1%) and those with negative serology (4.8%) for HBV markers were detected.

CONCLUSIONS

In this study we have improved a PCR technique successfully applied in hepatitis B prevalence studies in northeastern Mexico. Prevalence of hepatitis B in this region of Mexico is intermediate compared to countries of the northern hemisphere where prevalence is lower, and to countries of Southeast Asia and the Mediterranean region where it is highly endemic.

In vitro infection of human peripheral blood mononuclear cells by a defective hepatitis B virus with a deletion in the PreS1 region of the viral genome

Previously, we identified a defective hepatitis B virus (HBV) which contains a 183 nucleotide deletion in the PreS1 region of the viral genome affecting the S gene promoter in sera from hepatitis B surface antigen (HBsAg)-negative patients with serum HBV-DNA. The aim of this study was to analyse the infectivity of this mutant. Peripheral blood mononuclear cells (PBMC) from a healthy donor were incubated with serum samples from 2 HBsAg-negative patients with serum HBV-DNA (infected with wild-type and deletion mutant HBV), from an HBsAg carrier (infected with wild-type HBV) and from a healthy donor. After 1 week, HBV-DNA was detected by polymerase chain reaction (PCR) in all supernatants and cells incubated with the HBV-DNA-positive inocula. DNase and trypsin pretreatment confirmed intracellular localization of HBV-DNA in cells. HBV-RNA and covalently closed circular HBV-DNA were also detected in PBMC, indicating that the viral DNA infecting these cells was transcriptionally active. Deletion mutant and wild-type HBV were detected in the supernatants and cells infected with the two HBsAg-negative sera, while only wild-type HBV was detected in the supernatant and cells incubated with the serum from the HBsAg-carrier. In conclusion, this HBV deletion mutant can infect, replicate and release viral particles in in vitro infected PBMC.

NAT for HBV and anti-HBc testing increase blood safety

BACKGROUND

Routine HBV PCR screening of blood donations to our institutes was introduced in January 1997 to complete the NAT screening program for transfusion-relevant viruses. Testing was successively extended to customer transfusion services with a total of 1,300,000 samples tested per year.

STUDY DESIGN AND METHODS

Minipools of 96 blood donation samples were formed by automatic pipettors. HBsAg-reactive samples were included. HBV particles were enriched from the minipools by centrifugation. Conventional and in-house TaqMan PCRs were successively applied for HBV amplification. Sensitivity reached 1000 genome equivalents per mL for each individual donation. Confirmatory single-sample and single-sample enrichment PCRs were established with sensitivities of 300 and 5 to 10 genome equivalents per mL, respectively.

RESULTS

After screening of 3.6 million donor samples, 6 HBV PCR-positive, HBsAg-negative donations were identified. Two samples were from infected donors who had not seroconverted and four were from chronic anti-HBc-positive low-level HBV carriers. Retesting by single-sample PCR of 432 samples confirmed positive for HBsAg identified 37 donations that were negative in minipool PCR. Donor-directed look-back procedures indicated that no infected donor who had not yet seroconverted was missed by minipool PCR. However, recipient-directed look-back procedures revealed two anti-HBc-positive recipients of HBsAg-negative minipool PCR-negative, anti-HBc-positive and single-sample PCR-positive blood components. After testing randomly selected 729 HBsAg-negative minipool PCR-negative, anti-HBc-positive donors by single-sample enrichment PCR, 7 were identified with < or = 10 HBV particles per mL of donor plasma.

CONCLUSION

Minipool PCR testing after virus enrichment was sensitive enough to identify HBsAg-negative donors who had seroconverterd and HBsAg-negative, anti-HBc-positive chronic HBV carriers. HBV NAT in conjunction with anti-HBc screening would reduce the residual risk of transfusion-transmitted HBV infection.

Clinical significance of a highly sensitive enzyme immunoassay of hepatitis B surface antigen using a novel electron spin resonance technique

We developed a highly sensitive enzyme immunoassay (EIA), the p-AP/HHTIO method, that detects serum hepatitis B surface antigen (HBsAg) by measuring stabilized nitroxide radicals using a novel electron spin resonance technique [Matsuo et al. (1998) Free Radic Biol Med 25:929-935]. To demonstrate the clinical significance of this method and to reveal occult hepatitis B virus (HBV) infection in patients, we used the method to analyze serum samples of 30 patients with acute or fulminant hepatitis who were negative for HBsAg by standard EIA, and those of seven chronic HBV carriers who became negative for HBsAg during a follow-up period by standard EIA. We also examined serum HBV DNA by amplification of the HBV S gene, using the polymerase chain reaction (PCR) technique. The p-AP/HHTIO method showed that 9 of 20 (45%) patients with acute hepatitis and 2 of 10 (20%) with fulminant hepatitis were positive for HBsAg; PCR detected HBV DNA in these HBsAg-positive patients. Antibody against hepatitis B core antigen was detected in one patient with fulminant hepatitis. The p-AP/HHTIO method demonstrated prolonged seropositivity of HBsAg even after standard EIA showed a loss of HBsAg in all seven HBV carriers. Our p-AP/HHTIO method is useful for screening and diagnosing HBV infection in patients with liver diseases who are negative for conventional HBV-related serological markers.

Hepatitis B virus DNA in serum of healthy black African adults positive for hepatitis B surface antibody alone: possible association with recombination between genotypes A and D

In some patients with chronic liver disease induced by hepatitis B virus, viral DNA is known to persist in low concentration in serum after seroconversion to hepatitis B surface antibody-positivity. This phenomenon has, however, not been documented in asymptomatic black African carriers of hepatitis B virus. Using nested amplification by the polymerase chain reaction, we detected low concentrations of hepatitis B virus DNA in the serum of 6 of 23 (26%) healthy black African adults with normal liver function and with hepatitis B virus surface antibody as the only serological marker of the virus. This finding offers one explanation for the earlier observation of integrated hepatitis B virus DNA in hepatocellular carcinomas in black Africans whose serum was positive for surface antibody alone. A number of genetic changes were found in the six isolates that might be responsible for evasion of the immune response and persistence of the virus. Isolated mutations were detected in the "a" determinant of the surface gene and in the encapsidation signal. In all five isolates sequenced in the core promoter, mutations were present in the upstream regulatory region. Recombination between genotypes A and D was present in three of the isolates, including both of those in which the entire genome was sequenced. This change in genotype also overlapped the amino end of the polymerase domain and may result in sufficiently low levels of replication to allow viral persistence. Topoisomerase 1 specific trinucleotides were concentrated in the vicinity of the recombination breakpoints.

Occult hepatitis B virus infection

Many studies have shown that hepatitis B virus infection may also occur in hepatitis B surface antigen-negative patients. This occult infection has been identified both in patients with cryptogenic liver disease and in patients with hepatitis C virus-related chronic hepatitis, and much evidence suggests that it may be a risk factor of hepatocellular carcinoma development. However several aspects of this occult infection remain unclear such as its prevalence and the factor(s) involved in the lack of circulating hepatitis B surface antigen. Moreover, it is uncertain whether the occult hepatitis B virus infection may contribute to chronic liver damage, considering that it is usually associated with a suppressed viral replication. Evidence and hypotheses concerning this fascinating field of bio-medical research are reviewed.

Identification of a novel surface mutant of hepatitis B virus in a seronegative chronic liver disease patient

Hepatitis B virus (HBV) with mutations in the envelope proteins can emerge during natural infections, vaccinations or interferon therapy and appears occasionally to escape virus elimination or detection. The implications of such mutations at the molecular level are often obscure. We report the identification of a new surface mutant of HBV. This mutant was identified, and isolated from a chronic liver disease patient, negative for HBsAg as well as other serological markers but positive for HBV DNA. Several mutations were observed in the surface antigen gene out of which a Thr118-Ala118 change was predicted to have a destabilizing effect on the structural integrity of the 'a' determinant and also alter the antigenicity profile of the mutant HBsAg. Besides a RNA hairpin loop was predicted for the transcript generated by the small surface protein of this mutant, which could have an inhibitory effect at the translational level. These observations thus indicate that mutations in the surface gene could lead to a considerable decrease or complete absence of properly folded surface antigen which in turn could explain the absence of reactive HBsAg in the serum of the patient.

Quantitative DNA analysis of low-level hepatitis B viremia in two patients with serologically negative chronic hepatitis B

Low-level viremia due to hepatitis B virus (HBV) was demonstrated in the sera of two patients diagnosed previously as having non-B, non-C chronic hepatitis. Both patients had a "silent" HBV infection, because they were negative for both hepatitis B surface antigen (HBsAg) and anti-hepatitis B core antibody. The TaqMan chemistry polymerase chain reaction (PCR) amplified the HBV DNA, enabling quantitation of the virus in their sera. Their serum HBV DNA concentrations were low: the amount of each HBV S or X gene amplified showed there were approximately 10(3) copies/ml and HBV DNA was detected occasionally during clinical follow-up. Positive HBsAg staining in liver tissues was demonstrated by an immunoperoxidase technique. Vertical transmission of silent HBV from one patient to her daughter was confirmed. Direct nucleotide sequencing of the amplified HBV X region revealed several mutations, suggesting reduced viral replication. One patient had a T-to-C mutation at the extreme 5'-terminus of the direct repeat 2 region and the other exhibited a coexisting X region with a 155-nucleotide deletion. These findings suggest that HBV replication is suppressed considerably in patients with silent hepatitis B.

Persistence of infectious hepadnavirus in the offspring of woodchuck mothers recovered from viral hepatitis

Mother-to-child transmission is an important route for hepatitis B virus (HBV) dissemination. It has been established that HBV traces persist for years after complete clinical recovery from hepatitis B. Similarly, resolution of hepatitis caused by HBV-related woodchuck hepatitis virus (WHV) is followed by occult lifelong carriage of pathogenic virus. In this study, we documented that WHV persisting after termination of acute hepatitis is transmittable to newborns as an asymptomatic long-term infection. All 11 offspring from 4 dams studied carried transcriptionally active WHV genomes for 3.5 years after birth without immunovirological markers of infection. WHV genomes and mRNA were detected both in the liver and lymphoid tissue in the majority of offspring; WHV covalently closed circular DNA was detected in some samples. In 4 offspring, however, the virus was restricted to the lymphatic system. In the circulation, WHV DNA-reactive particles were DNase resistant and of comparable size and density to complete virions. Importantly, the virus in offspring with or without hepatic WHV DNA expression was infectious to WHV-naive woodchucks. Finally, offspring challenged with WHV were not protected against reinfection. These findings show that mothers with occult hepadnaviral carriage transmit pathogenic virus to their offspring, inducing a persistent infection invariably within the lymphatic system but not always in the liver.

Occult hepatitis B virus infection in patients with chronic hepatitis C liver disease

BACKGROUND

Hepatitis B virus (HBV) infections in patients who lack detectable hepatitis B surface antigen (HBsAg) are called occult infections. Although such infections have been identified in patients with chronic hepatitis C liver disease, their prevalence and clinical significance are not known.

METHODS

With the polymerase chain reaction, we searched for HBV DNA in liver and serum samples from 200 HBsAg-negative patients with hepatitis C virus (HCV)-related liver disease (147 with chronic hepatitis, 48 with cirrhosis, and 5 with minimal histologic changes). One hundred of the patients had detectable antibodies to the HBV core antigen (anti-HBc); 100 were negative for all HBV markers. Eighty-three were treated with interferon alfa. We also studied 50 patients with liver disease who were negative both for HBsAg and for HCV markers. In six patients found to have occult HBV infection, we evaluated possible genomic rearrangements through cloning or direct sequencing procedures.

RESULTS

Sixty-six of the 200 patients with chronic hepatitis C liver disease (33 percent) had HBV sequences, as did 7 of the 50 patients with liver disease unrelated to hepatitis C (14 percent, P=0.01). Among the 66 patients, 46 were anti-HBc-positive and 20 were negative for all HBV markers (P<0.001). Twenty-two of these 66 patients (33 percent) had cirrhosis, as compared with 26 of the 134 patients with hepatitis C infection but no HBV sequences (19 percent, P=0.04). HBV sequences were detected in 26 of the 55 patients in whom interferon therapy was ineffective and 7 of the 28 patients in whom interferon therapy was effective (P=0.06). None of the sequenced HBV genomes had changes known to interfere with viral activity and gene expression.

CONCLUSIONS

Occult hepatitis B infection occurs frequently in patients with chronic hepatitis C liver disease and may have clinical significance.

Expression of mutated hepatitis B virus X genes in human hepatocellular carcinomas

To explore the role of hepatitis B virus (HBV) X protein in liver carcinogenesis, independently from its role in viral replication, we have analyzed X gene structure and expression in tumorous and non-tumorous tissues obtained from 9 hepatitis B surface antigen (HBsAg)-negative, HBV DNA-positive patients. HBV replication was undetectable in tumorous tissues. HBV X gene was truncated at its 3' end in 5 of 9 tumorous tissues and 1 of 8 non-tumorous livers. Sequence analysis performed on uninterrupted X genes from 3 tumors and 3 surrounding non-tumorous tissues showed a high rate of mutations, selectively in the tumorous livers. In 1 of the 3 tumors, a frameshift mutation induced a new stop at codon 129. HBV RNAs were tested by reverse transcriptase-polymerase chain reaction (RT-PCR) with surface (S), core (C) and X specific primers. X, but not S and C, RNA expression was found in 6 of 8 tumors and in 6 of 7 non-tumorous tissues. This finding was consistent with immunohistochemical detection of X, but not S and C, antigens in all tumors also expressing X RNA. Our results provide evidence for selective expression of HBV X, but not S and C, RNA and protein in the tumorous and non-tumorous tissue of HBsAg-negative, HBV DNA-positive patients. It also shows that the structure of the X gene is modified (interrupted or highly mutated) in the majority of tumorous livers. Taken together, our findings are consistent with a potential role of mutated X proteins in HBV-related liver oncogenesis.

Characterization of unusual escape variants of hepatitis B virus isolated from a hepatitis B surface antigen-negative subject

Hepatitis B virus DNA was extracted from serial serum samples of a hepatitis B surface antigen-negative patient with antibodies to the core protein as the only marker of an infection with hepatitis B virus. This patient showed no symptoms of hepatic injury. Sequencing of the amplified viral DNA demonstrated multiple amino acid changes clustering in surface-exposed regions of the surface protein. Synthesis and association of the middle (M) and small (S) surface proteins could be shown in vitro. The variant surface antigens were recognized neither by monoclonal antibodies to the surface antigen nor by the vaccinee's sera. Consequences for hepatitis B surface antigen testing and vaccine development are discussed.

Mutations of the X region of hepatitis B virus and their clinical implications

Nucleotide (nt) sequences of the X region of more than 130 hepatitis B virus (HBV) isolates were determined and derived from patients with a variety of clinical features. Correlation of nt substitutions with clinicopathological characteristics was attempted. The X region (465nt) is crucial for the replication and expression of HBV because the X protein transactivates the HBV genes and this region contains the core promoter, enhancer II, and two direct repeats. There are several mutational hotspots, some of which seem to relate to immunological epitopes of the X protein. Two kinds of mutations which have important clinical significances were found. One is an 8-nt deletion between nt 1770 and 1777, which truncates 20 amino acids from the carboxyl terminus of the X protein. This deletion leads to the suppression of replication and expression of HBV DNA, resulting in immunoserological marker (HBsAg) negativity. This silent HBV infection is responsible for the majority of non-A to non-E hepatitis. The other mutation substituting T for C (nt 1655), T for A (nt 1764) and A for G (nt 1766) seems to relate to fulminant hepatitis. Further sequencing studies and in vitro mutagenesis experiments will clarify the significance of other mutations of the X region.

Long-lasting memory T cell responses following self-limited acute hepatitis B

The molecular and cellular basis of long-term T cell memory against viral antigens is still largely undefined. To characterize anti-viral protection by memory T cells against non-cytopathic viruses able to cause acute self-limited and chronic infections, such as the hepatitis B virus (HBV), we studied HLA class II restricted responses against HBV structural antigens in 17 patients with acute hepatitis B, during the acute stage of infection and 2.2 to 13 yr after clinical resolution of disease. Results indicate that: (a) significant T cell proliferative responses to HBV nucleocapsid antigens were detectable in all patients during the acute phase of infection and in 14/17 also 2-13 yr after clinical resolution of disease; b) long-lasting T cell responses were sustained by CD45RO+T cells, predominantly expressing the phenotype of recently activated cells; c) limiting dilution analysis showed that in some patients the frequency of HBV-specific T cells was comparable to that observed in the acute stage of infection and, usually, higher than in patients with chronic HBV infection; d) the same amino acid sequences were recognized by T cells in the acute and recovery phases of infection; and e) HBV-DNA was detectable by nested-PCR in approximately half of the subjects. to conclusion, our results show that vigorous anti-viral T cell responses are detectable in vitro several years after clinical recovery from acute hepatitis B. Detection of minute amounts of virus in some recovered subjects suggests that long-term maintenance of an active anti-viral T cell response could be important not only for protection against reinfection but also for keeping the persisting virus under tight control.

Increasing heterogeneity of the 'a' determinant of HBsAg found in the presumed late phase of chronic hepatitis B virus infection

To investigate if the concomitant presence of hepatitis B virus (HBV) DNA and antibodies to hepatitis B surface antigen (anti-HBs) is associated with mutations in the HBV envelope gene, selected sequences of the HBV genome in 54 patients with chronic liver disease, collected from the Wuhan district of China, were amplified by polymerase chain reaction (PCR) and the DNA sequences of the products were determined. The part of the S gene coding for the 'a' determinant of HBsAg was found to be prone to diversity. A total of 19 aberations occurring at 11 of the 69 nucleotide positions of this part of the genome were found in sera from 15 HBsAg-negative but anti-HBs-positive patients. One of 13 HBsAg/HBeAg-positive and 8 of 17 HBsAg/anti-HBe-positive samples also showed point mutations in this gene sequence. Most prevalent was a point mutation from adenine to guanine at nucleotide 530 resulting in a change from threonine to alanine at amino acid position 126. This study highlights that the long time course of chronic HBV infection could favour a selection of escape mutants. The occurrence of such HBV variants in patients with chronic liver disease are not detected by conventional HBV serology, and the patients can therefore easily by be misdiagnosed. If viral mutants like those described here can be transmitted to other patients, there will be difficulties in identifying these infections, and conventional HBV vaccination will presumably not be protective against them.

Development of a two-site immuno-PCR assay for hepatitis B surface antigen

Hepatitis B virus (HBV) gene transcription may occur at very low levels resulting in HBsAg concentrations in serum and liver below the limit of detection by currently available immunoassays. An assay has been developed that combines the specificity of two high affinity anti-HBs monoclonal antibodies (MAb) directed against distinct and separate determinants in the 'a' domain of HBsAg with the highly sensitive polymerase chain reaction (PCR) detection method. Following capture of HBsAg present in serum samples, the second anti-HBs MAb, which is biotinylated, is added. Binding of the second antibody allows the subsequent specific binding of streptavidin and a biotinylated linear DNA molecule derived from a bluetongue virus (BTV) gene. Presence of this DNA is then detected by PCR using BTV-specific primers. The PCR product is quantified by a liquid-phase oligonucleotide enzymatic assay, which further increases the sensitivity of the technique. The use of a two-site MAb capture and PCR detection system for HBsAg was shown to greatly enhance the specificity and sensitivity of the assay and detect as little as 0.5 pg of HBsAg in serum samples. It is suggested that the principles of this technique could be applied to measure other low level viral antigens in serum and biological samples.

Hepatitis B and D genomes in hepatitis B surface antigen negative patients with chronic hepatitis C

Hepatitis B and hepatitis D viral genomes were tested by nested polymerase chain reaction in the serum and liver of 69 hepatitis B surface antigen (HBsAg) negative, anti-hepatitis C virus (HCV) positive patients (47 with HCV RNA and 22 without HCV RNA). Serum hepatitis B virus (HBV) DNA-was detected in 49% of the patients with HCV-RNA and in 64% of those without HCV-RNA. Furthermore, intrahepatic HBV-DNA was found in four of five (80%) of the biopsies analysed. Delta genome was found in 72% and 73%, respectively, of the anti-HCV positive patients with or without HCV-RNA. In addition, intrahepatic delta virus genome was detected in another four liver biopsies studied. In the group of patients with HCV-RNA, the simultaneous presence of hepatitis B and D genomes was statistically higher in transfused patients than in drug addicts, or in those with an unknown infection route (P < 0.001). These results show a high percentage of B and D genomes in HBsAg negative patients with anti-HCV, irrespective of the presence or absence of the HCV genome. However, the clinical implications of this finding should be examined in future studies.

Detection of hepatitis B and woodchuck hepatitis viral DNA in plasma and mononuclear cells from heparinized blood by the polymerase chain reaction

Amplification by the polymerase chain reaction (PCR) of hepatitis B virus (HBV) DNA extracted from parallel samples of serum and heparinized plasma gave contradictory results, indicating that heparin inhibits virus detection. Similarly, analysis of PCR products of woodchuck hepatitis virus (WHV) DNA showed that heparinization of blood abolished WHV DNA amplification, while anticoagulation with sodium EDTA or acid citrate dextrose did not. Amplification of recombinant WHV and HBV DNA in the presence of increasing concentrations of sodium heparin progressively inhibited and finally abolished virus genome detection. The inhibitory effect of heparin was reversed by treatment of either plasma or isolated DNA with heparinase (5 U/reaction, 1 h at 28 degrees C) prior to PCR. In contrast, heparin did not influence the detection of hepadnavirus in peripheral blood mononuclear cells (PBMC), even after prolonged incubation of the cells with heparin in culture. These findings confirm that heparin exerts a dramatic inhibitory effect on hepadnaviral DNA detection by PCR and they demonstrate that this effect can be reversed by heparinase. The findings also show that extensively washed PBMC derived from heparinized blood can be a reliable source of nucleic acids for amplification of hepadnavirus genome. These results imply that previous data should be reassessed if samples of heparinized plasma were found hepadnavirus DNA nonreactive by PCR or when these samples were used as a starting material for PCR quantitation of viral genome.

Precore and X region mutants in hepatitis B virus infections among renal dialysis patients

Hepatitis B virus (HBV) variants containing mutations within the X and the precore regions of the viral genome were demonstrated by polymerase chain reaction (PCR) amplification and DNA sequencing in renal dialysis patients with different serological patterns of HBV infection. Among carriers, X region deletion mutants predominated in patients who lost hepatitis B e antigen (HBeAg), or developed anti-HBe, but not in persistently HBeAg-positive patients. The precore region remained wild type in all carriers whether or not they seroconverted from HBeAg to anti-HBe. The frequency of precore and X region mutants was greatest among non-carrier patients with viral antibodies as the only indication of infection and among patients with non-A, non-B hepatitis (NANBH), suggesting an inverse relationship between the presence of wild type HBV markers and the presence of HBV mutants. Furthermore, the detection of one but not the other mutation in many serum samples suggests that these mutations are independently selected for during infection. Finally, the absence of HBV DNA in 21 'uninfected' dialysis patients with normal transaminases and no viral serology, suggests that replication of these mutants is associated with hepatitis. These results have important implications for HBV screening and treatment, as well as for the pathogenesis of chronic infection.

Pathogenesis of posttransfusion viral hepatitis in children with beta-thalassemia

The pathogenesis of posttransfusion hepatitis was determined in 14 children with beta-thalassemia. All had blood samples obtained in 1980 or 1981, were vaccinated against hepatitis B virus in 1983 and had another serum sample collected in 1989. Seven children had detectable antibodies against hepatitis C virus before vaccination, and all were positive in 1989. With specific solid-phase enzyme immunoassays, all children had antibodies against hepatitis B virus, X and polymerase antigens in 1981, and six had one or both antibodies in 1989. Hepatitis B virus infection was confirmed by means of polymerase chain reaction, which demonstrated virus DNA in 13 of the 14 children. The amplification products spanning the X/precore region were smaller than expected, suggesting mutations in this region. Cloning and sequencing of these products revealed deletions spanning part or all of the X gene. The results show that these children were infected with hepatitis B virus even without other markers in serum, that hepatitis B persists years after vaccination and that such infections are associated with the presence of X deletion mutants. Coinfection with hepatitis B and C viruses, the former containing a new class of variants, is common in children with beta-thalassemia.

Presence of hepatitis B and C viral genomes in US blood donors as detected by polymerase chain reaction amplification

Hepatitis C virus (HCV) represents a major cause of posttransfusion hepatitis worldwide. Posttransfusion hepatitis associated with hepatitis B virus (HBV) continues to occur. HBsAg-negative donor sera from the Rhode Island Blood Center between 1987 and 1988 were screened using more sensitive techniques to assess the prevalence of low level HBV infection. Group I consists of 866 healthy blood donors without HBV serologic markers, group II consists of 377 donors with ALT elevations (> 45 IU/L), group II consists of 148 donors positive for anti-HBc, and group IV consists of eight donors positive for both surrogate markers. A sensitive monoclonal immunoradiometric assay (M-IRMA) was employed for detection of HBsAg-associated epitopes (detection limit of 20 pg/ml) in serum. A subset of sera were analyzed for the presence of HBV DNA using the method of anti-HBs capture of HBV related virions in serum followed by polymerase chain reaction (PCR) amplification. Using these techniques, 0.8% and 1.7% of donors were positive for HBsAg and HBV DNA respectively in group I. In contrast, 0.9% and 9.5% in group II and 0.7% and 18.1% in group III were positive, respectively. There were eight donors with both ALT elevation and anti-HBc; and four (50%) of these were positive for HBV DNA. In the group with anti-HBc, the majority (80%) of donors with HBV DNA had either no or low (signal to noise ratio < 10) anti-HBs titer. Using anti-HCV testing and reverse transcription-PCR for detection of HCV genomes, we detected evidence of HCV infection in nine of the 49 donors with low level HBV DNA.(ABSTRACT TRUNCATED AT 250 WORDS)

Genetic heterogeneity of hepatocellular carcinoma

We studied 80 hepatocellular carcinomas from three continents for p53 gene (TP53) mutations and hepatitis B virus (HBV) sequences. p53 mutations were frequent in tumors from Mozambique but not in tumors from South Africa, China, and Germany. Independent of geographic origin, most tumors were positive for HBV sequences. X gene coding sequences of HBV were detected in 78% of tumors, whereas viral sequences in the surface antigen- and core antigen-encoding regions were present in less than 45% of tumors. These observations indicate that hepatocellular carcinomas are genetically heterogeneous. Mozambican-type of hepatocellular carcinomas are characterized by a high incidence of p53 mutations related to aflatoxins. In other tumors, the rarity of p53 mutations combined with the frequent presence of viral X gene coding sequences suggests a possible interference of HBV with the wild-type p53 function.

Hepatitis B virus persistence after recovery from acute viral hepatitis

Contrary to current opinion, the disappearance of hepatitis B surface antigen (HBsAg) from the serum, the development of anti-HBs antibodies, and normalization of liver function may not reflect complete virological recovery from acute hepatitis B virus (HBV) infection. By using the polymerase chain reaction (PCR), in the current study we demonstrate long-term persistence of HBV DNA in the serum and peripheral blood mononuclear cells (PBMC) of four patients for up to 70 mo after complete clinical, biochemical, and serological recovery from acute viral hepatitis. Serum HBV DNA reactivity co-sedimented with HBsAg in sucrose gradients, and it displayed the size and density characteristics of naked core particles and intact HBV virions, presumably contained within circulating immune complexes in these anti-HBs antibody-positive sera. HBV DNA was also present in PBMC in late convalescent samples from all four patients, and HBV RNA was detected in late convalescent phase PBMC in two of these patients. These results suggest that HBV DNA, and possibly HBV virions, can be present in the serum, and that the viral genome can persist in a transcriptionally active form in PBMC for > 5 yr after complete clinical and serological recovery from acute viral hepatitis.

Variant of hepatitis B virus isolated in Zimbabwe

The polymerase chain reaction (PCR) was used to amplify an approximately 1.2 kb DNA fragment encompassing the pre-S/S gene region of HBV DNA from serum of patients with acute hepatitis B virus infection. Nucleotide sequence analysis revealed a number of interesting features in the S gene region. Two Bam HI sites were located at nucleotide positions 557 and 872, respectively, in the S gene. Guanine (G) was found at nucleotide position 903 as part of AGA, the codon for arginine (R) corresponding to amino acid position 122 of the S protein. Adenine (A) was found at nucleotide position 1017 as part of AAA, the codon for lysine (K) corresponding to amino acid position 160 of the S protein. Nucleotide sequence alignment revealed a 97% homology to the corresponding domain of an HBVadw genome (clone pFDW294). Within the second loop of the "a" determinant, two mutations resulting in substitution of serine or threonine with the hydrophobic amino acids, methionine at position 143 and with alanine in place of glycine at position 145, are predicted from the consensus nucleotide sequence of the PCR-derived clones. Subtyping with monoclonal antibodies showed that the HBsAg was of the ayw subtype.