Antiviral treatment of chronic hepatitis B virus infection: infectious virus cannot be detected in patient serum after permanent responses to treatment

Infectivity of Hepatitis B Virus Surface Antigen-Positive Plasma With Undetectable HBV-DNA: Can HBsAg Screening Be Discontinued in Egyptian Blood Donors?

Hepatitis B Virus (HBV) infectivity data were reviewed and the 50% infectious dose (ID50) was reassessed in different HBsAg-positive infection stages enabling modelling of transfusion-transmitted (TT)-HBV infection risk if HBsAg donor screening was replaced by individual donation nucleic acid amplification technology (ID-NAT). Quantitative HBsAg and HBV-DNA assays were performed against international standards to compare the ratio between potential infectious HBV virions and subviral HBsAg particles in Egyptian HBsAg-positive blood donors as well as in Japanese chimpanzee samples of known infectivity. HBV-DNA load below the quantification limit of detection was estimated against a reference standard by replicate NAT testing (n = 25). Infectivity of chimpanzee samples collected during ramp-up and declining viremic phase were tested in a human liver chimeric mice (HLCM) model and compared with published infectivity data from different HBsAg-positive infection stages. Lowest estimates of ID50 in HBsAg-positive plasma were 3-6 HBV virions in chimpanzee studies. Infectivity decreased approximately 10-100-fold in the declining viremic phase using HLCM. In acute phase samples, HBV to HBsAg particle ratios varied between 1:102-104 but in HBsAg-positive blood donors this particle ratio reached 1:106-1012 when viral load was below 100 HBV-DNA copies/mL. Modelled TT-HBV risk of an HBsAg-positive/ID-NAT nonreactive blood transfusion was estimated at 5.5%-27% for components containing 20-200 mL of plasma when assuming an ID50 of 316 (point estimate between 100 and 1000) virions. It cannot be ensured that discontinuation of HBsAg donor screening and reliance on ID-NAT alone is safe.

Infectivity of hepatitis B virus (HBV) surface antigen (HBsAg) positive plasma with undetectable HBV-DNA: Can HBsAg screening be discontinued in Egyptian blood donors?

HBV infectivity data were reviewed and the 50% infectious dose (ID50 ) was reassessed in different HBsAg positive infection stages enabling modelling of transfusion-transmitted (TT)-HBV infection risk if HBsAg donor screening was replaced by individual donation nucleic acid amplification technology (ID-NAT). Quantitative HBsAg and HBV-DNA assays were performed against international standards to compare the ratio between potential infectious HBV virions and subviral HBsAg particles in Egyptian HBsAg positive blood donors as well as in Japanese chimpanzee samples of known infectivity. HBV-DNA load below the quantification limit of detection was estimated against a reference standard by replicate NAT testing (n = 25). Infectivity of chimpanzee samples collected during ramp-up and declining viremic phase were tested in a human liver chimeric mice (HLCM) model and compared with published infectivity data from different HBsAg positive infection stages. Lowest estimates of ID50 in HBsAg positive plasma were 3-6 HBV virions in chimpanzee studies. Infectivity decreased approximately 10-100-fold in the declining viremic phase using HLCM. In acute-phase samples, HBV to HBsAg particle ratios varied between 1:102 -104 but in HBsAg positive blood donors this particle ratio reached 1:106 -1012 when viral load was below 100 HBV-DNA copies/ml. Modelled TT-HBV risk of an HBsAg positive/ID-NAT nonreactive blood transfusion was estimated at 9%-46% for components containing 20-200 ml of plasma assuming an ID50 of 316 (point estimate between 100 and 1000) virions. In the Egyptian setting, discontinuation of HBsAg donor screening and reliance on ID-NAT alone seems to be unsafe.

Chronic viral hepatitis

Chronic viral hepatitis is a common clinical problem; it must be differentiated from other forms of chronic liver disease by history, laboratory data, and liver biopsy. This article reviews the treatment of chronic hepatitis B, delta hepatitis, and nonA and nonB viral hepatitis and emphasizes the controlled trials when available.

Suppressor T-cell activity in chronic hepatitis B-virus infection: relationship with the presence of HBV-DNA in serum

Suppressor T-cell activity and allogeneic T-cell response to concanavalin A (ConA) were investigated in 46 patients chronically infected with hepatitis B virus (HBV). Thirty-eight patients had chronic active hepatitis, seven of whom were superinfected with Delta virus, and eight were healthy chronic HBV carriers. T-cell suppressor activity was in the normal range in healthy carriers and in patients negative for serum HBV-DNA, independent of the e antigen status. In contrast, the group of patients positive for HBV-DNA exhibited a significant reduction in suppressor activity. Longitudinal studies in patients who cleared serum HBV-DNA demonstrated that suppressor T-cell activity became normal thereafter. These results suggest a relationship between suppressor T-cell function and the stage of viral replication in individuals with chronic HBV infection.

Relation of the hepatitis B virus carrier state to hepatocellular carcinoma

The attempt to divide the large group of chronic HBsAg carriers into "healthy" vs. those with chronic hepatitis of various intensities is sometimes difficult. The major problems are overlap in clinical manifestations, hepatic test results and histologic as well as virologic features. Nevertheless, this separation is not only conceptually important, but may also be useful in patient management, particularly because of the risk of transition to cirrhosis and HCC. Although at least 75% of patients with HCC associated with HBV have cirrhosis, the time point at which the cirrhosis developed is not established, particularly since the vast majority of chronic HBsAg carriers fall into the "healthy" category. Important unanswered questions are, therefore: how often do "healthy" carriers develop cirrhosis and/or HCC, including the time relations between the two? Does the transformation to HCC result from one or several identifiable acute events in the "healthy" carrier (or in mild CPH) or is it a gradual process of progressing chronic hepatitis B in which intercurrent exacerbations may still play a role? Do the quantitative observations as to the relation between persistent HBV infections and HCC in the East apply to Western countries? Our hypothesis concerning pathogenesis is based on pathologic, molecular, clinical and epidemiologic observations and concepts, and is supported by studies of hepadna virus-infected animals. This thesis proposes that integration of HBV DNA into host chromosomes in acute or chronic hepatitis or during the "healthy" carrier state corresponds to an initiation event similar to that described in chemical carcinogenesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes of hepatitis B virus (HBV) markers during prolonged recombinant interferon alpha-2A treatment of chronic HBV infection

Eleven HBsAg chronic carriers were treated with recombinant-interferon (rIFN)-alpha-2A with either 20 X 10(6) (n = 6) or 10 X 10(6) IU/m2 body surface (n = 5), i.m. twice weekly for 6 months. HBV-markers were tested monthly for 15 months. Throughout the follow-up, 6 patients (54%) became HBeAg, HBV-DNAp and HBV-DNA negative (responders). In addition, 8 were HBcAg-negative, 10 anti-HBc-IgM-negative and 2 HBsAg/IgM complexes negative. All patients gave polymerized human serum albumin receptors and HBsAg-positive results. The low rIFN dose seems to be more efficient for clearing HBV-markers than the high dose. Responder patients already showed lower (P less than 0.05) HBsAg concentration and HBsAg/IgM complexes levels in their basal samples as compared to non-responders, and exhibited under rIFN treatment significant decreases (P less than 0.05) in all HBV-markers studied. In conclusion, the most reliable HBV-markers to be assayed in the evaluation of antiviral therapy are HBV-DNA, HBV-DNAp or HBcAg. The testing of pHSA-R, HBsAg/IgM complexes and anti-HBc-IgM does not seem to be very useful.

Conjugates of ara-AMP with lactosaminated albumin: a study on their immunogenicity in mouse and rat

Complexes of albumin with oligosaccharides have been successfully employed in experimental chemotherapy as hepatotropic carriers of antiviral drugs or as vectors of anticancer-agents, but their clinical use is hampered by an immune response they might evoke. In the present experiments we have studied the humoral immunogenicity of conjugates of 9-beta-D-arabinofuranosyl adenine 5'-monophosphate (ara-AMP) with lactosaminated albumin (L-SA), in mice and rats. These complexes were prepared with the aim of increasing the chemotherapeutic index of ara-AMP in the treatment of chronic hepatitis B virus (HBV) infection. L-SA-ara-AMP conjugates prepared with heterologous albumin produced antibodies in mice and rats when repeatedly injected intraperitoneally. The same conjugates prepared with homologous albumin induced only low amounts of antibodies, when given by repeated intraperitoneal injection, whereas they did not evoke antibodies in mice and were tolerogenic in rats when administered repeatedly by the intravenous route. These results suggest that in a clinical use of drug conjugates prepared with oligosaccharide-albumin complexes the risk of an immune response can be reduced by employing human albumin and by injecting the conjugates by the intravenous route.

Distribution of a conjugate of 9-beta-D-arabinofuranosyladenine 5'-monophosphate (ara-AMP) with lactosaminated albumin in parenchymal and sinusoidal cells of rat liver

9-beta-D-Arabinofuranosyladenine 5'-monophosphate (ara-AMP) coupled to lactosaminated human albumin (L-HSA), injected i.v. into rats, selectively enters the liver. The conjugate concentration in parenchymal and sinusoidal hepatic cells, isolated by collagenase perfusion, was found to be practically equal in both cell types. This indicates that the high uptake of L-HSA-ara-AMP complex by the whole liver also corresponds to a high conjugate concentration in hepatocytes where ara-AMP should be targeted in order to increase its chemotherapeutic index in chronic hepatitis B treatment.

Interferons in the treatment of chronic hepatitis B virus infection

Hepatitis B virus offers several properties that may help to determine how antiviral substances, such as interferon, work. A description of the phases of chronic hepatitis B virus infection is presented, as well as the rationale for interferon therapy as treatment.

Drug targeting in antiviral chemotherapy. A chemically stable conjugate of 9-beta-D-arabinofuranosyl-adenine 5'-monophosphate with lactosaminated albumin accomplishes a selective delivery of the drug to liver cells

With the aim of improving the chemotherapeutic index of 9-beta-D-arabinofuranosyl-adenine 5' monophosphate (ara-AMP) in the treatment of chronic hepatitis B, this drug was conjugated with lactosaminated serum albumin (L-SA), a neoglycoprotein which only enters into hepatocytes. We used a L-SA-ara-AMP conjugate which, in contrast to those previously employed, has the advantage of remaining soluble after lyophilization. We found in mice that: (I) this new conjugate was quite stable in the bloodstream where only a small part of ara-AMP was released; (II) after administration of the conjugate labelled in the drug moiety both acid insoluble and soluble radioactivities were several times higher in liver than in other organs; (III) in mice with Ectromelia virus hepatitis, the conjugate inhibited virus DNA synthesis in liver without affecting cellular DNA synthesis in intestine and bone marrow; (IV) the conjugate did not display any recognizable sign of acute toxicity even at doses several fold higher than those pharmacologically active; and (V) when prepared with homologous albumin it was not immunogenic.

Hepatitis in clinical practice. 1. Hepatitis A and B

As is evident from the foregoing discussion, hepatitis A and hepatitis B are not static, passé disease. Knowledge concerning these illnesses continues to expand at a fantastic rate--all of it of extreme practical clinical significance. Most interesting is the elucidation of the etiology of the acquired immune deficiency syndrome (AIDS) and the increase this knowledge is hoped to produce on the utilization of hepatitis B vaccine. Also extremely important is the development of recombinant DNA vaccine, which will permit total circumvention of the question of AIDS and safety of the hepatitis B vaccine.

Preliminary trial of recombinant fibroblast interferon in chronic hepatitis B virus infection

Five patients with chronic hepatitis B were treated with 8-day courses of leukocyte (alpha) interferon (5 X 10(6) U/day) and with 8-day courses of recombinant fibroblast (betaser) interferon at dosages of 5 X 10(6), 35 X 10(6), and 105 X 10(6) U/day. Inhibition of hepatitis B virus replication as evidenced by a decrease in DNA polymerase (DNAP) activity was seen during all treatment courses. Equivalent reduction in DNAP was seen from the low-dose alpha and beta ser regimens, but beta ser interferon at 35 X 10(6) U/day achieved a significantly greater decrease in DNAP activity than did the low-dose regimens. In no patient, however, was permanent loss of DNAP noted. Because of dose-limiting toxicity, only two patients were escalated to the 105 X 10(6)-U/day dosage level. Transient proteinuria was noted in two patients while they were receiving interferon. This has not been noted in other patients receiving this preparation and could not be explained by the development of anti-interferon antibodies. This study has defined an appropriate dosage for future longer-term trials of this agent alone and in combination with other antivirals for the treatment of chronic hepatitis B.

Therapeutic activity of vidarabine in symptomatic chronic active hepatitis related to HBV

The potential inhibitory effects of nucleoside analogues such as ARA-A and acyclovir on HBV-DNA-polymerase were first demonstrated in vitro and then confirmed in vivo in open dose finding studies. The therapeutic efficacy of both ARA-A and ARA-AMP which appeared the most potent drugs was then confirmed by various studies in symptomatic HBeAg-positive patients. These studies demonstrated a similar benefit of therapy with 38 and 40% of treated patients given ARA-A and ARA-AMP, respectively, who permanently cleared HBV replication after a single course, and 67-80% who did so after two courses. Significant improvement in transaminases and histologic activity was also documented (P less than 0.001). Myalgias were observed in 10 and 30% of the patients, respectively. Patients who failed to respond to nucleosides, and those coinfected with HDV, were treated with interferons. Out of 8 cases of HDV/CAH given 5 MU thrice weekly of fibroblast beta-interferon (UPSA) for 3 months, DNA-p activity fell transiently in all 6 initially elevated cases. A parallel decrease in anti-HD titers (P less than or equal to 0.05), inflammation (P less than or equal to 0.001) and necrosis (P less than or equal to 0.05) were observed. alpha-Recombinant interferon was given i.m. for 4 months (2-7 MU/m2 X 2/7 days) to 10 CAH with high DNA-p values. HBV replication was permanently inhibited in 4 cases and dramatically reduced in 3 additional patients. Three failed to respond. Careful monitoring of DNA-p values appeared to be the single most important factor in assessing activity.

Analysis of DNA polymerase reaction products for detecting hepatitis B virus in serum--comparison with spot hybridization technique

An assay for DNA polymerase reaction products using slab gel electrophoresis and autoradiography was compared with the spot hybridization technique for the detection of hepatitis B virus DNA in 317 blood samples. The former could identify the nature and size of DNA on electrophoresis, and reduce potentially false-positive results due to artifacts. Discordant results between the two methods occurred in 36 of 317 samples; 22 were positive by the spot technique alone, and 14 were positive by the analysis of DNA polymerase reaction products alone. However, the samples positive with the spot test alone showed weak radioactive signals on electrophoresis/autoradiography that were often interpreted as "inconclusive" by blind observations. Correlation of hepatitis B e antigen/antibody with hepatitis B virus DNA was studied in 91 patients with various chronic liver diseases. Discordant results, i.e., presence of the DNA in antibody positive sera, or its absence in the antigen positive sera, were obtained in 15 (19%) cases. Such patients tended to have advanced liver disease with fluctuating serum aminotransferase levels. Analysis of DNA polymerase reaction products by slab gel electrophoresis and autoradiography is not only sensitive, but is also as specific as the Southern blot technique in the detection of hepatitis B virus DNA in serum, and may prove useful in selected samples, especially where no cloned hepatitis B virus DNA is available, or in search of new hepatitis B virus-like viruses.

Acyclovir enhances the antiviral effect of interferon in chronic hepatitis B

Patients with chronic hepatitis B with active viral replication had a significantly greater fall in DNA polymerase and hepatitis-Be antigen when treated with interferon and acyclovir together than when treated with either interferon or acyclovir alone. Apart from fatigue and thrombophlebitis, tolerance of the combination therapy was excellent. The combination therapy appears the most promising for conversion of a state of active viral replication into virus latency.

Combination of short-term prednisolone and adenine arabinoside in the treatment of chronic hepatitis B. A controlled study

The efficacy of adenine arabinoside (Ara-A) alone or in combination with prednisolone utilizing its withdrawal effect was studied in 43 patients with deoxyribonucleic acid polymerase- and hepatitis B e antigen-positive chronic hepatitis. Ten patients were treated with 10 mg/kg body wt of Ara-A alone for 4-8 wk. In 9 cases, prednisolone (40 mg/day) was given at a constant dosage for 4 wk before Ara-A treatment. Fourteen patients received oral prednisolone alone for 4 wk, and 10 patients served as untreated controls. Six of 9 patients (67%) undergoing the combination therapy became seronegative for hepatitis B e antigen, whereas only 4 of 24 patients (17%) treated either with Ara-A alone or prednisolone alone lost the antigen. Two of the 10 untreated patients became seronegative for hepatitis B e antigen during the same follow-up period of 9 mo. This prospective controlled study suggests that the combination of immunomodulation by steroid withdrawal and subsequent Ara-A is more effective in the treatment of patients with chronic liver disease and active hepatitis B virus replication than treatment with Ara-A alone.

Recombinant leukocyte interferon treatment of chronic hepatitis B

We have investigated the efficacy of a relatively prolonged course of recombinant leukocyte interferon treatment in 14 chronic HBsAg-, HBeAg-, hepatitis B virus DNA- and DNA polymerase-positive carriers. alpha-Interferon was administered for 9 weeks. Six of 14 treated carriers have a sustained loss of HBeAg, hepatitis B virus DNA and DNA polymerase. Four subsequently lost HBsAg (28.5%). Elevated pretreatment SGPT concentrations, histologic chronic active hepatitis, an exacerbation of chronic hepatitis with an increase in SGPT concentrations in the last weeks of treatment and possibly recent onset of the carrier state was associated with complete inhibition of viral replication. None of 11 matched, untreated HBsAg-, HBeAg-, hepatitis B virus DNA- and DNA polymerase-positive carriers monitored during the same period lost HBsAg. The effect of recombinant leukocyte interferon may require an appropriate host-immune response. The efficacy of recombinant leukocyte interferon therapy is restricted, but it may be of benefit in a proportion of carriers, if these carriers can be precisely identified.

Activities of arabinosyladenine monophosphate and 9-(1,3-dihydroxy-2-propoxymethyl)guanine against ground squirrel hepatitis virus in vivo as determined by reduction in serum virion-associated DNA polymerase

Treatment of chronic ground squirrel hepatitis virus infection with arabinosyladenine monophosphate at 20 mg/kg per day for 3 weeks caused marked decreases in serum virion-associated DNA polymerase concentrations in three of five squirrels. Statistically significant but less dramatic decreases in enzymatic activity were noted in two of six squirrels treated with 50 mg of 9-(1,3-dihydroxy-2-propoxymethyl)guanine per kg per day. After therapy, DNA polymerase activities rose to pretreatment levels.

Asymmetric replication of hepatitis B virus DNA in human liver: demonstration of cytoplasmic minus-strand DNA by blot analyses and in situ hybridization

In situ and blot hybridization techniques have been used with strand- and region-specific probes to characterize the forms of hepatitis B virus (HBV) DNA in the liver of a patient with chronic active hepatitis B. The hepatocytes contain a heterogeneous population of rapidly migrating DNA species in the 0.5-1.4 kb position that are localized predominantly in the cytoplasm and are of minus-strand polarity. The findings indicate that the replication is asymmetric, with separate pathways for plus- and minus-strand synthesis of HBV DNA; that viral DNA synthesis is initiated at a site near the nick in the minus strand of virion DNA; and that actively replicating forms of HBV DNA can be identified at the cellular level by in situ hybridization.

[Anti-HBc IgM in acute and chronic hepatitis B virus infection]

Hepatitis B core antigen (HBcAg) synthesized in E. coli was used for determination of immunoglobulin M class-specific antibodies against HBcAg. It was found that 98% of cases with acute hepatitis B surface antigen (HBsAg) positive hepatitis type B were anti-HBc immunoglobulin M (IgM) positive. Atypical hepatitis B was detected in 33% of anti-HBc-positive HBsAg-negative cases with acute hepatitis. Anti-HBc IgM was positive for 6 months in acute resolving hepatitis type B, whereas cases resulting in chronic hepatitis B remained anti-HBc IgM-positive for up to 900 days. Chronic HBsAg carriers with severe liver disease had anti-HBc IgM more often than individuals with minor liver damage; 83% of HBsAg-positive liver cirrhoses, 63% of chronic aggressive hepatitis, 50% of HBsAg-positive liver carcinoma, but only 17% of chronic persistent hepatitis or 7% of healthy blood donors were anti-HBc IgM-positive. Determination of anti-HBc IgM is useful in detecting atypical hepatitis B virus infections without HBsAg in serum and, with some restrictions, in discriminating acute and chronic hepatitis type B.

Targeting of antiviral drugs by coupling with protein carriers

Side effects of antiviral drugs might be circumvented by their selective delivery into infected cells. This targeting can be obtained by conjugation of the drugs to macromolecules which are taken up specifically by the infected cells. The experiments reviewed, on this approach to antiviral chemotherapy, are mainly directed at improving the chemotherapeutic index of adenine arabinoside (ara-A) in the treatment of chronic hepatitis B by its coupling to galactosyl terminating glycoproteins.

Interferons as antivirals in man

Interferons have now been used in both prophylaxis and treatment of a number of human viral infections. The major action has been as a prophylactic for sites within the body that are not yet involved by disease. Such a prophylactic effect can be obtained early in the treatment of acute viral infection or even during chronic viral disease. Both local and systemic prophylaxis have been achieved with regard to both respiratory and herpesviral illness. In addition, Dane particle suppression can be achieved consistently with dosages of 10(6) units or greater daily to patients with chronic hepatitis B virus infection. In certain cases with prolonged therapy there can be permanent eradication. With leucocyte-derived material of approximately 10(6) or 10(7) units per milligram protein, the major side effects have been an initial febrile response, fatigue, malaise, marrow suppression, and inhibition of hair growth. So far, side effects have been rapidly reversible on lowering of dosage. Present studies with the use of lymphoblastoid interferon and bacterial-derived interferon employ materials of significantly greater specific activity. Such experience suggests that the same general side effects that were limiting with leucocyte interferon are present with interferon produced from recombinant DNA by bacterial as well as with lymphoblastoid interferon.

Preliminary studies of acyclovir in chronic hepatitis B

Three patients with HBsAg-positive and DNA-polymerase-positive chronic hepatitis were treated with increasing dosages of intravenous acyclovir. A fall in DNA polymerase activity was seen with all courses of acyclovir but no dose-response relationship was evident. In only one patient did DNA polymerase fall to zero where it has remained for five months. Two out of 10 courses were associated with significant side effects with the highest dosages of acyclovir but these promptly resolved when the agent was stopped. Acyclovir's apparently partial and transient action suggests that it will not have a role in the treatment of chronic hepatitis B virus infection.