Riboprobe assay for HDV RNA: a sensitive method for the detection of the HDV genome in clinical serum samples

Serum immunoglobulin M antibody to hepatitis D as a surrogate marker of hepatitis D in interferon-treated patients and in patients who underwent liver transplantation

The kinetics of the immunoglobulin (Ig) M type antibody to the hepatitis D virus (IgM anti-HD) were investigated in hepatitis B surface antigen (HBsAg) carriers with chronic hepatitis D treated with interferon (IFN) and in patients with terminal hepatitis delta virus (HDV) cirrhosis who underwent liver transplantation. The IgM antibody disappeared in each of 8 patients who responded to IFN therapy with the persistent normalization of aminotransferases and with the clearance of serum HBsAg and HDV-RNA. The IgM reactivity did not decline in the 45 treated patients who did not respond to the cytokine or who experienced a relapse after responding while on therapy. The antibody rapidly disappeared from serum post-transplantation in each of 10 examined patients with HDV who underwent transplantation. In 5 patients who underwent transplantation and who became reinfected with HDV, the antibody remained undetectable during the early reinfection phase, as marked by HDV replication and by the absence of liver damage; however, it rapidly raised to pre-transplantation levels with the recurrence of hepatitis D (HD) in the liver graft. Monomeric 7S IgM anti-HD predominated over pentameric 19S antibody in each of the two patients examined for IgM anti-HD molecular species. The IgM antibody to HDV raises in response to HDV-induced damage and represents a valid surrogate marker of liver damage which is immunopathologically related to HDV infection. Besides providing diagnostic information, it provides the best predictor of impending resolution of chronic HDV disease, whether spontaneous or IFN-induced.

Diagnostic value of anti-hepatitis D virus (HDV) antibodies revisited: a study of total and IgM anti-HDV compared with detection of HDV-RNA by polymerase chain reaction

A high serum titre (> or = 1000 or > or = 5000) of total antibody to hepatitis D virus (anti-HDV) and positive for immunoglobulin (Ig)M anti-HDV have been used to represent HDV replication, while reverse transcription-polymerase chain reaction (RT-PCR) is currently the most sensitive assay for detecting HDV viraemia. The aim of the present study was to re-evaluate the correlation of total anti-HDV and IgM anti-HDV with HDV viraemia based on RT-PCR and to assess the clinical significance of these markers in acute and chronic HDV superinfection. Chronic HDV infection was defined as positive HDV-RNA by RT-PCR for more than 6 months, while total anti-HDV titre was defined by serial dilution. Of 178 hepatitis B virus (HBV) carrier patients studied, 119 cases had been anti-HDV positive for more than 6 months. Two-thirds (79/119) were positive for HDV viraemia by RT-PCR. Only half the chronic HDV viraemic patients had a high titre (> or = 1000) of total anti-HDV, and there was only moderate agreement (kappa = 0.41) between total anti-HDV titre/IgM anti-HDV and HDV-RNA and chronic HDV viraemia. Based on cross-sectional and longitudinal follow-up analyses, serum total anti-HDV titres > or = 100 appeared to be an excellent cut-off titre (kappa = 0.91) in differentiating chronic from acute HDV infection among viraemic patients. In summary, IgM and a high titre total of anti-HDV are not good markers of HDV viraemia, but an anti-HDV titre of > or = 100 appears to be an excellent marker for the differentiation of acute from chronic HDV superinfection.

Detection of hepatitis D virus RNA in serum by a reverse transcription, polymerase chain reaction-based assay

We designed a reverse transcription, polymerase chain reaction-based assay for serum hepatitis D virus RNA. Amplified hepatitis D virus cDNA was revealed by ethidium bromide staining, followed by blotting onto a nylon membrane and hybridization with a 32phosphorus-labelled oligonucleotide, or by a DNA enzyme immunoassay (DEIA) using a double stranded DNA-specific monoclonal antibody. The absolute sensitivity was expressed as number of hepatitis D virus RNA molecules, using a serum of known viral RNA concentration. Three sets of primers were used, encompassing the base positions 66-686 (variable rod-stabilizing region), 701-962 (conserved, viroid-like domain) and 886-1,333 (portion of the open reading frame 5 encoding for the carboxyterminus of the hepatitis D antigen) of the viral genome. The lower detection limits, after amplification of the three RNA portions, as assessed by ethidium bromide staining, were 7.5 x 10(6), 7.5 x 10(4) and 7.5 x 10(2) molecules of hepatitis D virus RNA per assay, respectively. The region encompassing bases 886-1,333 was chosen for blotting and hybridization to a radiolabelled oligonucleotide probe or for a capture-based DNA enzyme immunoassay, where the microplate was coated with this same probe. The two procedures showed comparable sensitivity, i.e., about 10 molecules of viral RNA per assay. The specificity of the assay was further on a panel of both anti-hepatitis D-positive and -negative sera. Amplification of serum hepatitis D virus RNA by reverse transcription/polymerase chain reaction followed by detection of the amplified cDNA by DNA enzyme immunoassay is a promising and feasible routine assay for detecting low amounts of circulating virions.

Natural history of hepatitis D viral superinfection: significance of viremia detected by polymerase chain reaction

BACKGROUND/AIMS

Polymerase chain reaction (PCR) is very sensitive. The aim of the study was to reevaluate viral replication in hepatitis D virus (HDV) superinfection by PCR.

METHODS

HDV and hepatitis B virus (HBV) were detected by PCR in 185 patients.

RESULTS

The acute hepatitis group had the highest detection rate of HDV RNA compared with chronic hepatitis, cirrhosis, hepatocellular carcinoma, and remission groups (63 of 64 vs. 35 of 47, 17 of 23, 19 of 30, and 7 of 21) and the highest alanine aminotransferase (ALT) levels (mean, 1741 U/L vs. 266 to 27 U/L; P < 0.05). The detection rate of HBV DNA was the lowest in the acute group (41%) compared with 66%, 70%, 80%, and 57% in the remaining groups (P < 0.02). At the chronic stage, 13%-25% of cases had HDV RNA, and 30%-48% of cases had HBV DNA detected by PCR but not by traditional method. HDV RNA was associated with ALT levels in horizontal and longitudinal analyses.

CONCLUSIONS

HDV superinfection may be divided into the following three phases: acute phase, active HDV replication and suppression of HBV with high ALT levels; chronic phase, decreasing HDV and reactivating HBV with moderate ALT levels; and late phase, development of cirrhosis and hepatocellular carcinoma caused by replication of either virus or remission resulting from marked reduction of both viruses.

Clinical relevance of the detection of hepatitis delta virus RNA in serum by RNA hybridization and polymerase chain reaction

Hepatitis delta virus nucleic acid was detected by dot-blot hybridization using RNA probe and reverse transcription/polymerase chain reaction amplification in 223 serum samples from 66 patients with hepatitis D virus infection. Seven cases with chronic hepatitis D virus infection were treated with interferon: six for 3 months and one for 7.5 years. By using the primers located in the putative conserved regions, the technique of reverse transcription/polymerase chain reaction amplification was 10(3) to 10(4) times more sensitive than that of dot-blot hybridization. The main findings of this study are: (i) HDV RNA could be detected in the absence of any other serological hepatitis D virus marker in serum from acute hepatitis patients with IgM anti-HBc; (ii) high titer anti-HD antibodies (IgM and total anti-HD) persisted in patients during short-term interferon treatment, and in one patient during long-term interferon treatment, despite clearance of serum HDV RNA even after 3 years; (iii) total anti-HD alone was detected in the absence of IgM anti-HD and serum HDV RNA. These observations indicate that the detection of HDV RNA by molecular techniques in serum is a useful, sensitive and non-invasive technique for the early diagnosis and follow up of hepatitis D virus infection, as well as for the monitoring of antiviral therapy. In addition, total anti-HD antibody in the absence of HDV RNA may be the only residual marker of past infection. Finally, the choice of the technique for hepatitis D virus detection is important for the optimal assessment of the clinical stage and monitoring of antiviral therapy in hepatitis D virus-infected patients.

Hepatitis delta virus RNA in serum of patients with chronic delta hepatitis

We studied 28 patients with chronic delta hepatitis for the presence of hepatitis delta virus (HDV) RNA in serum. The hot start polymerase chain reaction (PCR) method, in which the reaction begins at 60-80 degrees C, showed a higher sensitivity than conventional PCR reaction. Additionally, the presence of hepatitis B (HBV) and C virus (HCV) infections were determined by PCR. HDV RNA was detected in 26 patients (93%), HBV DNA in 22 (79%), and HCV RNA in only one. Detection of HDV RNA correlated very well with detection of hepatitis delta antigen by immunostaining in the liver. In six patients HDV RNA was detectable despite the absence of HBV DNA in serum, suggesting that high levels of HBV are not required for HDV replication. Of 29 control patients with chronic hepatitis B without antibody to HDV, none had detectable HDV RNA, while all had HBV DNA in serum. Detection of HDV RNA with PCR proved highly sensitive and specific, demonstrating that virtually all patients with chronic HDV infection had ongoing viral replication.

A genotype of hepatitis D virus that occurs in northern South America

Hepatitis D virus (HDV) is the cause of an unusually severe form of liver disease with distinct histologic features (morula cell) that occurs throughout northern South America and certain other areas of the world. Clinical studies of HDV disease worldwide indicate that there is, in fact, a wide variation in pathogenesis, and the reasons for these differences are presently unknown. One possible explanation is that factors associated with the viral genotype are determinants of HDV pathogenesis. In this study, nucleic acid sequences were determined for three different northern South American HDV isolates which were obtained from individuals with severe disease or a family history of severe disease, in areas that are hyperendemic for this disease pattern. The sequences of these three isolates are very similar to one another but only distantly related to other published HDV sequences. Comparison of the sequence of a semiconserved region from a total of 14 isolates indicates that there are at least three HDV genotypes. Most published HDV sequences, including those from North America, Europe, the Middle East, the South Pacific, and Asia, belong to a single genotype which may have some geographically based subtypes. A single Japanese isolate is the sole representative of a second HDV genotype. The South American sequences reported here constitute a third genotype. The association of a particular genotype with the severe form of type D hepatitis that occurs in northern South America supports the hypothesis that HDV genetic factors are important determinants in the pathogenesis of type D hepatitis.

Delta hepatitis: molecular biology and clinical and epidemiological features

Hepatitis delta virus, discovered in 1977, requires the help of hepatitis B virus to replicate in hepatocytes and is an important cause of acute, fulminant, and chronic liver disease in many regions of the world. Because of the helper function of hepatitis delta virus, infection with it occurs either as a coinfection with hepatitis B or as a superinfection of a carrier of hepatitis B surface antigen. Although the mechanisms of transmission are similar to those of hepatitis B virus, the patterns of transmission of delta virus vary widely around the world. In regions of the world in which hepatitis delta virus infection is not endemic, the disease is confined to groups at high risk of acquiring hepatitis B infection and high-risk hepatitis B carriers. Because of the propensity of this viral infection to cause fulminant as well as chronic liver disease, continued incursion of hepatitis delta virus into areas of the world where persistent hepatitis B infection is endemic will have serious implications. Prevention depends on the widespread use of hepatitis B vaccine. This review focuses on the molecular biology and the clinical and epidemiologic features of this important viral infection.

Direct detection of circulating hepatitis C virus RNA using probes from the 5' untranslated region

Diagnostic testing for hepatitis C virus (HCV) infection currently is based on the presence of anti-HCV antibodies or a positive HCV RNA polymerase chain reaction (PCR) test. Although HCV RNA PCR is a sensitive and specific technique, widespread application is limited. Moreover, HCV RNA PCR is subject to false-positive reactions through contamination and is inherently difficult to standardize and quantitate. To overcome limitations of HCV RNA PCR, we produced both cDNA and riboprobes from a 241 nucleotide sequence of the 5' untranslated region of the HCV genome for slot hybridization. Hybridization was absent using normal human serum, horse serum, or hepatic cellular RNA from noninfected liver. Hybridization occurred predominantly with positive-stranded HCV RNA and was abolished by pretreatment with RNase A. Slot hybridization was performed on serum samples from 60 patients with chronic HCV infection and a positive HCV RNA PCR and 20 patients with liver diseases unrelated to HCV who had a negative HCV RNA PCR. Slot hybridization with cDNA and riboprobes showed concordance with HCV RNA PCR of 95 and 98.3%, respectively. There were no false-positive reactions in controls. The sensitivity of riboprobe hybridization was comparable to that of one stage HCV RNA PCR using 5' untranslated region primers. Riboprobe hybridization with the HCV H strain standard was positive in the dilution corresponding to 10(-6) chimpanzee infectious doses50/ml. The density of the hybridization signals correlated significantly with the mass of an RNA standard extracted from the liver of a patient with HCV infection. The relative quantities of HCV RNA in the sera of selected patients varied and were not correlated with the duration of disease or the histopathological stage. The highest relative quantities were associated with concurrent immunosuppression. We conclude that slot hybridization is a sensitive, specific alternative to HCV RNA PCR that can be directly quantitated using appropriate HCV RNA standards.

Patterns of hepatitis delta virus reinfection and disease in liver transplantation

Twenty-seven carriers of the hepatitis B surface antigen who underwent liver transplantation in Italy and Belgium for terminal Hepatitis delta virus (HDV) cirrhosis were investigated. In 22 of the patients, HDV infection recurred. Two patients died of coexisting HDV and hepatitis B virus (HBV) reactivation. Four patients who died of unrelated causes were found to have HDV without signs of HBV reactivation. Five patients (18%) cleared both HBV and HDV after transplantation with no evidence of hepatitis (mean follow-up, 29 months). In many surviving patients. HDV infection recurred early without signs of HBV reactivation. Disease returned in the 11 HDV-infected patients in whom HBV also recurred. Histological hepatitis did not recur during an interim of 12-33 months in the 5 HDV-infected patients in whom HBV did not return. The overall medium-term survival in patients with HDV who underwent transplantation was 77.7%. Liver transplantation offers patients with HDV a hope of cure from disease despite a high risk of reinfection. In the transplantation setting. HDV can cause subclinical infections without any apparent assistance from HBV; these infections become symptomatic only if and when HBV reactivates. Thus, HDV may not be in itself pathogenic but requires cooperation from HBV to cause the appearance of the disease.

Evaluation of commercial enzyme immunoassays for detection of hepatitis delta antigen and anti-hepatitis delta virus (HDV) and immunoglobulin M anti-HDV antibodies

Panels of hepatitis B virus surface antigen-positive sera from drug abusers were used to evaluate 14 commercial enzyme immunoassays from six companies for detecting hepatitis delta virus (HDV) markers. For detecting hepatitis delta virus antigen (HDAg), the Wellcome, Pasteur and Noctech assays had 100% sensitivity for all 42 HDAg-positive serum specimens that were confirmed in-house; the Organon reagents gave 59.5% sensitivity without detergent and 64.3% sensitivity with detergent, but there were 14 discrepant results with and without detergent. The Sorin assay detected HDAg in only 10 of the positive samples (23.8% sensitivity). For the detection of antibody to HDV (anti-HDV) all six commercial enzyme immunoassays were reactive with all 36 anti-HDV-positive specimens that were confirmed in-house. There were no false-positive results with the Wellcome, Noctech, or Sorin assay, but one specimen was false positive by the Organon assay. One HDAg-positive specimen gave a false anti-HDV-positive result in the Abbott assay and an equivocal result in the Pasteur assay (97.8% specificity). For the detection of immunoglobulin M anti-HDV, the Wellcome, Noctech, and Sorin assays agreed for the 38 positives confirmed in-house, except for one false negative with the Sorin test. We conclude that there has been a substantial improvement over previously evaluated assays in sensitivity and specificity of commercial assays for anti-HDV detection, and the sensitivities of immunoglobulin M anti-HDV assays are also comparable. However, there are still major differences in sensitivity among some assays for HDAg detection.

Significance of IgM anti-hepatitis D virus (HDV) in chronic HDV infection

Intrahepatic hepatitis D virus (HDV) antigen (HDAg) and serum HDV RNA are excellent markers of active HDV replication but the relation of IgM anti-HDV to HDV replication and histological activity is less certain. To further elucidate the significance of serum IgM anti-HDV, 90 paired sera and liver biopsies from 64 patients seropositive for total antibody to HDV were analysed for IgM anti-HDV, intrahepatic HDAg expression, and histological inflammatory activity. IgM anti-HDV was strongly associated with intrahepatic HDAg expression with a sensitivity of 94.1% but the assay lacked specificity since 14 out of 22 cases negative for intrahepatic HDAg were also positive for IgM anti-HDV. In 20 patients in whom follow-up biopsies and paired sera were available, two patients lost intrahepatic HDAg but paired serum remained IgM anti-HDV positive. Although the presence of serum IgM anti-HDV correlated significantly with a higher histological inflammatory activity (P = 0.001), there was a considerable overlap with the group seronegative for IgM anti-HDV, again indicating a poor specificity. This lack of specificity of IgM anti-HDV for both HDV replication and histological activity indicates that this assay provides no additional information over and above assay for total antibody to HDV.

Hepatitis B virus replication modulates pathogenesis of hepatitis D virus in chronic hepatitis D

Hepatitis D virus and hepatitis B virus nucleic acids were detected by Northern and Southern blot hybridization in the sera and livers of 85 chronic carriers of HBsAg and anti-hepatitis D followed up for a mean of 10 yr. We identified three subsets of patients: 13 with hepatitis D virus and hepatitis B virus viremia, 53 with serum hepatitis D virus RNA, but without hepatitis B virus DNA and 19 negative for both nucleic acids. Genomic and subgenomic forms of hepatitis D virus RNA were detected only in patients with hepatitis D virus and hepatitis B virus viremia. Histological findings and disease activity at admission were comparable in the three groups of patients, but the outcome was significantly worse in patients with active replication of both viruses; two of them died of terminal liver failure and hepatocellular carcinoma developed in two; the remaining patients had an uneventful course. These results suggest that active hepatitis B virus replication represents an important previously unrecognized determinant of severe liver damage in patients with chronic hepatitis D virus infection. Since hepatitis B virus provides the means for hepatitis D virus secretion and release from infected cells, active hepatitis B virus multiplication favoring the spread of hepatitis D virus from cell to cell may increase the pathogenetic potential of the defective agent.