Anti-HDV reflex testing in HBsAg-positive subjects: An efficacious strategy to identify HDV infection.

BACKGROUND AND AIMS: The prevalence of HDV infection in HBsAg carriers is about 9.9% in Italy. However, the real prevalence is underestimated because the anti-HDV test is not performed routinely in all HBsAg carriers. The aim of this study was to compare the prevalence and the absolute number of HDV infection identified in HBsAg-positive subjects tested at University Hospital Federico II before and after the introduction of anti-HDV reflex testing. METHODS: From January to December 2022, reflex test for the detection of total HDV antibodies was performed in all HBsAg-positive subjects tested at University Hospital Federico II. The control group consisted of all the HBsAg-positive subjects tested at the same laboratory in 2019, before the implementation of anti-HDV reflex testing. Sera were evaluated with ADVIA Centaur HBsAgII Qualitative, Liaison Murex HBsAg Quantitative and Liaison Murex Total Anti-HDV Qualitative. RESULTS: Before reflex testing, anti-HDV had been tested in 16.4% (84/512) of HBsAg-positive subjects, while after its implementation, 100% (484/484) of HBsAg-positive patients was tested for anti-HDV. The anti-HDV positive prevalence was lower than before the introduction of reflex test (10.7% vs. 16.6%) but the absolute number of anti-HDV positive patients increased (14 vs. 52 subjects). HDV-RNA was detectable in 26 (53%) of 49 tested subjects. CONCLUSIONS: Our data showed that the implementation of anti-HDV reflex testing increased the diagnoses of HDV infection. In this setting, due to the approval of specific anti-HDV drugs, a reflex test for anti-HDV should be implemented to early identify patients with HBV/HDV infection.

EASL Clinical Practice Guidelines on hepatitis delta virus.

Hepatitis D virus (HDV) is a defective virus that requires the hepatitis B virus to complete its life cycle and cause liver damage in humans. HDV is responsible for rare acute and chronic liver diseases and is considered the most aggressive hepatitis virus. Acute infection can cause acute liver failure, while persistent infection typically causes a severe form of chronic hepatitis which is associated with rapid and frequent progression to cirrhosis and its end-stage complications, hepatic decompensation and hepatocellular carcinoma. Major diagnostic and therapeutic innovations prompted the EASL Governing Board to commission specific Clinical Practice Guidelines on the identification, virologic and clinical characterisation, prognostic assessment, and appropriate clinical and therapeutic management of HDV-infected individuals.

Hepatitis delta genotype 5 is associated with favourable disease outcome and better response to treatment compared to genotype 1.

BACKGROUND & AIMS: Coinfection with HDV causes rapid progression to liver cirrhosis and hepatic decompensation in patients with chronic hepatitis B. Factors that are associated with disease progression are poorly understood. In this study we aim to identify risk factors associated with disease progression and better characterise clinical differences and treatment response between HDV genotype 1 and 5. METHODS: In this retrospective study, all patients under our care between 2005 and 2016 with HBV/HDV coinfection (HBsAg+, anti-HDV antibodies positive) were analysed. Patients were excluded if follow-up was less than 6 months, if they had HCV and/or HIV coinfection or an acute HDV infection. Demographic data, stage of liver disease, development of liver complications and treatment response were recorded. RESULTS: One-hundred seven patients (mean age 36.0 years, 57% male) were followed for a median period of 4.4 years (range 0.6-28.1 years); 64% were of African origin and 17% were of European origin, with 28% of patients being cirrhotic at first visit; 43% patients had actively replicating HDV virus (anti-HDV-IgG+, anti-HDV-IgM+ or HDV RNA+) and 57% of patients were HDV exposed (anti-HDV-IgG+, HDV RNA-). Patients with actively replicating HDV more often developed liver complications than HDV-exposed patients (p = 0.002), but no differences in baseline characteristics were observed. Patients with HDV genotype 5 less often developed cirrhosis or hepatic decompensation compared to patients with HDV genotype 1. Twenty-four patients were treated with peg-IFN and post-treatment response was significantly better in patients infected with genotype 5 (10% GT1 vs. 64% GT5, p = 0.013). CONCLUSION: Patients infected with HDV genotype 5 appear to have a better prognosis with fewer episodes of hepatic decompensation and better response to peg-IFN treatment than patients infected with HDV genotype 1. LAY SUMMARY: Hepatitis delta is a virus that affects the liver. The virus is known to have different subtypes, called genotypes. With this research we discovered that hepatitis delta virus genotype 1 behaves differently than genotype 5 and causes faster development of liver disease. This is important for education of our patients and to determine how often we need to check our patients.

Prevalence of antibodies against Hepatitis D virus (HDV) in blood donors in Northern Germany.

OBJECTIVE: To assess the prevalence of HDV infections in German blood donors. METHOD: 167 donors with acute/chronic or resolved HBV infection and detectable antibodies against Hepatitis B core antigen (anti-HBc) were tested for antibodies against HDV (anti-HDV) by competitive ELISA. Samples with detectable anti-HDV or with HBsAg and/or HBV DNA were additionally investigated for HDV RNA. RESULTS: In nine (5.4 %) of the 167 donors, also HBsAg and HBV DNA were detectable. Anti-HDV was detectable in two of the 167 donors (1.2 %), additional four donors (2.4 %) had a borderline result. All of these donors tested negative for HBsAg and HBV DNA. Neither in samples with anti-HDV nor in HBsAg-/HBV DNA-positive samples, HDV RNA was detectable. CONCLUSIONS: At least 1.2 % of anti-HBc-positive blood donors have had an HDV infection. Although there is some evidence for a somewhat higher prevalence of HDV, the overall prevalence of HDV in Northern Germany is low.

[Detection of markers of hepatitis B and D virus infection in biological media and dried blood spots.]

The aim of this study was to assess the rates of detection of the major markers of infection with hepatitis B and Delta (D) viruses in serum, saliva and dry blood dots (DBS) as a possible option for serological studies among the population of the endemic region in conditions of limited laboratory resources. For this purpose, paired samples of blood serum and DBS, blood serum and saliva from patients with chronic hepatitis B with Delta agent living in the Republic of Tyva, which is endemic for this disease. HBsAg was detected in 289 (100%) serum samples, in 88/92 (95.7%) saliva samples, in 60/80 (75%) DBS samples, stored three years at room temperature, and in 111/117 (94.9%) DBS stored one year at the same conditions. Anti-HBcore was detected in 209 (100%) serum samples, while in saliva and DBS samples this marker was detected in only 13.04% (12/92) and 19.7% (23/117), respectively. Anti-HDV antibodies in serum were detected in 209 (100%) samples collected from patients in 2017-2018. In saliva and DBS anti-HDV were not detected in any sample. This difference in the detection rates of anti-HBcore and anti-HDV might be accounted for the fact that the HBV core protein is a very strong immunogen, indusing the production of anti-HBcore in high concentrations. Probably, the concentration of anti-HDV is much lower, which explains its absence in saliva and DBS in patients with hepatitis B+D. Samples of biological media (saliva), as well as DBS can serve as an alternative material for the detection of HBsAg in screening and research prevalence studies. Meanwhile, the definition of anti-HDV in such media is not possible due to the false negative results. Due to the high probability of superinfection with HDV in patients with HBV in endemic areas, the detection of HBsAg in alternative media (saliva or DBS) should be followed by testing for anti-HDV in serum samples.

Prevalence, characteristics, and virologic correlations of hepatitis delta (D) among patients with hepatitis B surface antigen in Mongolia.

Clinical and biochemical features of hepatitis delta virus (HDV) infections in Mongolia remain largely unknown. We aimed to investigate the clinical characteristics of HDV patients in Mongolia using several markers. The 143 hepatitis B surface antigen (HBsAg)-positive patients were divided into 122 HDV-positive and 21 HDV-negative patients by HDV RNA positivity. Subgroup analysis was performed between hepatitis B e antigen (HBeAg)-positive and -negative HDV-positive patients. Liver function, quantitative HBsAg (qHBsAg), anti-HDV Immunoglobulin (Ig) M, Mac-2 binding protein glycosylation isomer (M2BPGi), hepatitis B virus (HBV) DNA level, and HDV RNA level were tested. HDV RNA was positive in 85.3% (122/143) of patients showing anti-HDV IgG. Liver disease activity was higher in HDV-positive patients than in HDV-negative patients. The HDV-positive group included a higher proportion of patients with high qHBsAg and M2BPGi levels (p < 0.001). The positivity rate for anti-HDV IgM was significantly higher in the HDV-positive group (p < 0.001). HDV RNA levels showed an inverse correlation with qHBsAg levels in HBeAg-positive-HDV-positive patients (r = -0.49, p = 0.034), and a positive correlation with qHBsAg levels in HBeAg-negative patients (r = 0.35, p < 0.001). Hepatitis B virus (HBV) DNA and HDV RNA levels did not show any correlation. M2BPGi levels likewise did not correlate with HDV RNA levels. A high positivity rate for HDV RNA was observed for HBV patients in Mongolia using the highly sensitive HDV RNA assay. The positivity rate for anti-HDV IgM was high in HDV RNA-positive patients. Severity of liver disease and M2BPGi levels were both high in the HDV RNA-positive group.

Prevalence and clinical course of hepatitis delta infection in Greece: a 13-year prospective study.

BACKGROUND & AIMS: Hepatitis D virus (HDV) has decreased in Europe, but recent reports indicate a rising trend. We report the epidemiological changes, clinical progress, and effect of treatment on the natural course of HDV infection in Greece during the last 13 years. METHODS: Prospective data were extracted from the HepNet.Greece Cohort-Study. RESULTS: Since 1997, 4673 chronic HBV (CHB) cases (4527 adults, 146 children) have been followed prospectively. Two thousand one hundred thirty-seven patients were tested for anti-HDV [101 (4.7%) positive]. Anti-HDV testing in Greece decreased significantly (57.0% before 2003, 35.3% thereafter; p<0.001). Anti-HDV prevalence among HBsAg-positives was 4.2%; lower in native Greeks (2.8%) than in immigrants (7.5%) or in children (15.3%; p<0.001). Within 2.3 years of follow-up, HDV occurred in 11/2047 HBsAg-positive patients (2.2 new delta-infected adults and 8.7 children per 1000 HBsAg-positive annually). HDV-positive compared to CHB adults were younger (p=0.035) and had more active and advanced disease at baseline, as indicated by laboratory indices and the higher prevalence of cirrhosis at younger age. During a 4.2-year median observation, significantly more anti-HDV-positive than CHB adults developed a liver-related first event (20.0% vs. 8.5%, p Log-rank=0.014).Treatment was received by 46/90 (51.1%) patients, 40 of them interferon-based. In multivariable analysis, interferon significantly decreased disease progression in HDV-positive patients [HR=0.14 (95% CI: 0.02-0.86; p=0.033)]. CONCLUSIONS: In Greece, HDV serology is currently tested in only one-third of HBsAg-positive patients. HDV prevalence is lower in native Greeks compared to immigrants, who may contribute >50% of the HDV infection burden in Greece. Data show that HDV infection is a rapidly progressive disease, but interferon-based treatment may alter its course.

Association of HLADQ-B1 polymorphisms in three generations of chronic hepatitis B patients.

The presence of polymorphisms in the human leukocyte antigen (HLA)-DQB1 gene, along with its expression, has been demonstrated to be correlated with spontaneous clearance and susceptibility to HBV infection. The present study aimed to evaluate the possible role of genetic polymorphisms in HLA-DQB1 in three generations of patients with chronic hepatitis B (CHB). Based on the inclusion criteria, 90 CHB patients, 18 individuals recovered from HBV infection, and 40 healthy subjects were chosen. The DNA contents of the whole blood samples were extracted in order to perform HLA-DQB1 typing by the PCR technique. Besides whole blood samples, sera were applied to measure liver function tests (LFTs), as well as the titers of anti-HDV and anti-HCV. Also, in all CHB patients were measured liver stiffness (LSM) by Fibro Scan. The results of HLA-DQB1 polymorphisms (rs2856718 and rs7453920) demonstrated that the majority of polymorphisms in CHB patients were HLA-DQB1*03, HLA-DQB1*05, HLA-DQB1*04:01 and HLA-DQB1*03:01 that associated with HBV persistence and chronicity. Among the patients who showed these polymorphisms, the mean±SD, LSM was 4±1.57 KPa and most of them, F grade was reported as F2, which was a sign of disease progression towards chronicity. HLA polymorphisms imputation revealed that HLA-DQB1*06:04 (3.4%, P-Value= 0.2) was detected only in healthy subjects as protective polymorphism, while the allele HLA-DQB1*03:03 was reported in both healthy subjects (P-Value= 0.06) and recovered patients (P-Value= 0.1) as suppressor of CHB formation. The allele HLA-DQB1*05:02 was found in both healthy subjects (3.4%) and CHB patients (4.5%) which was associated with risk to liver cirrhosis (P-Value= 0, OR: 0.002 0.95CI: 0.000-0.15). HLA polymorphism analysis indicated that 17.39% of patients who were seropositive for anti-HCV carried the HLA-DQB1*03:01. HBV resistance or infection risk could be assessed by DBQ1 typing. The existence of polymorphisms in HLA gene could influence the clearance (HLA-DQB1*03:03) or susceptibility and persistence of infection (HLA-DQB1*03, HLA-DQB1*05, HLA-DQB1*04:01 and HLA-DQB1*03:01). These results have the potential to improve personalized therapy and prognosis for HBV infection.

Is Slovakia Almost a Hepatitis D Free Country?

BACKGROUND: It is assumed that the prevalence of hepatitis D in HBsAg-positive individuals reaches 4.5-13% in the world and on average about 3% in Europe. Data from several European countries, including Slovakia, are missing or are from an older period. METHODS: We analyzed all available data on hepatitis D from Slovakia, including reports from the Slovak Public Health Authority and the results of one prospective study, and three smaller surveys. The determination of anti-HDV IgG and IgM antibodies and/or HDV RNA was used to detect hepatitis D. RESULTS: In the years 2005-2022, no confirmed case of acute or chronic HDV infection was reported in Slovakia. The presented survey includes a total of 343 patients, of which 126 were asymptomatic HBsAg carriers, 33 acute hepatitis B, and 184 chronic hepatitis B cases. In a recent prospective study of 206 HBsAg-positive patients who were completely serologically and virologically examined for hepatitis B and D, only 1 anti-HDV IgG-positive and no anti-HDV IgM or HDV RNA-positive cases were detected. In other smaller surveys, two anti-HDV IgG-positive patients were found without the possibility of HDV RNA confirmation. In total, only 3 of 329 HBsAg-positive patients (0.91%) tested positive for anti-HDV IgG antibodies, and none of 220 tested positive for HDV RNA. CONCLUSION: The available data show that Slovakia is one of the countries with a very low prevalence of HDV infection, reaching less than 1% in HBsAg-positive patients. Routine testing for hepatitis D is lacking in Slovakia, and therefore it is necessary to implement testing of all HBsAg-positive individuals according to international recommendations.

Hepatitis B virus and hepatitis D virus infection in women with or at risk for HIV infection in the United States.

Hepatitis D virus (HDV) requires co-infection with hepatitis B virus (HBV). Human immunodeficiency virus (HIV) shares transmission routes with these viruses. Among 4,932 US women infected with or at-risk for HIV during 1994-2015, HBV surface antigen (HBsAg) positivity was more common in women with HIV (2.8% vs. 1.2%; p = 0.001); HDV was more common among participants enrolled during 2013-2015 (p = 0.0004) and those with resolved rather than active hepatitis C (1.9% vs. 0.5%; p = 0.02). Among HBsAg-positive women (n = 117), HDV antibody prevalence was 22% and did not vary by HIV status; HDV infection was associated with the presence of advanced fibrosis/cirrhosis at enrollment (adjusted odds ratio, 5.70; 95% confidence interval, 1.46-22.29). Our results demonstrate the importance of HDV testing in HBV-infected US women.

Modeling the Interplay between HDV and HBV in Chronic HDV/HBV Patients.

Hepatitis D virus is an infectious subviral agent that can only propagate in people infected with hepatitis B virus. In this study, we modified and further developed a recent model for early hepatitis D virus and hepatitis B virus kinetics to better reproduce hepatitis D virus and hepatitis B virus kinetics measured in infected patients during anti-hepatitis D virus treatment. The analytical solutions were provided to highlight the new features of the modified model. The improved model offered significantly better prospects for modeling hepatitis D virus and hepatitis B virus interactions.

Implementation of anti-HDV reflex testing among HBsAg-positive individuals increases testing for hepatitis D.

Background & Aims: Although EASL guidelines recommend anti-HDV testing in all HBsAg-positive individuals, HDV infection remains an underdiagnosed condition. We describe the impact of an HDV screening program by reflex anti-HDV testing in all HBsAg-positive samples and compare the results before and after its implementation. Methods: In total, 2,236 HBsAg-positive determinations were included from January 2018 to December 2021. Only the first sample from each participant was evaluated: 1,492 samples before reflex anti-HDV testing (2018-2020) and 744 samples after (2021). Demographic and clinical characteristics of anti-HDV-positive patients were collected. Results: Before reflex testing, anti-HDV had been tested in 7.6% (114/1492) of HBsAg-positive individuals: 23% (91/390) attended in an academic hospital and only 2% (23/1,102) in primary care centres. After reflex testing was established, 93% (691/744) of HBsAg-positive cases were evaluated for anti-HDV: 91% (533/586) in the academic hospital and 100% (158/158) in primary care. The anti-HDV-positive prevalence was similar before and after reflex testing: 9.6% (11/114) and 8.1% (56/691), respectively. However, the absolute number of anti-HDV-positive patients increased. Most anti-HDV-positive patients were young, HBeAg-negative, Caucasian males. HDV-RNA was detectable in 35 (65%) of 54 tested, HBV-DNA was undetectable in 64%, and alanine aminotransferase levels were normal in 48%. Conclusions: Anti-HDV reflex testing quintupled the absolute number of diagnoses of chronic hepatitis D infection. Before the reflex test, a large percentage of HBsAg-positive individuals had not undergone any anti-HDV determination. Implementation of reflex testing increases the diagnosis of patients with chronic hepatitis D. Lay summary: Chronic hepatitis delta (CHD) is a viral disease caused by HDV, which requires the presence of HBV to propagate. HDV infection can cause rapid progression to cirrhosis, among other severe complications. The prevalence of CHD worldwide is controversial, and the infection often goes unrecognised, mainly because of unawareness among physicians. Use of reflex testing in other viral hepatitis has proven to increase detection and linking-to-care of infected patients. Implementation of anti-HDV testing in all HBsAg-positive patients has led to a 5-fold increase in the number of HDV diagnoses in an academic hospital and primary care centres.

A Rapid Point-of-Care Test for the Serodiagnosis of Hepatitis Delta Virus Infection.

Hepatitis Delta virus (HDV) is a satellite of the Hepatitis B virus (HBV) and causes severe liver disease. The estimated prevalence of 15-20 million infected people worldwide may be underestimated as international diagnostic guidelines are not routinely followed. Possible reasons for this include the limited awareness among healthcare providers, the requirement for costly equipment and specialized training, and a lack of access to reliable tests in regions with poor medical infrastructure. In this study, we developed an HDV rapid test for the detection of antibodies against the hepatitis delta antigen (anti-HDV) in serum and plasma. The test is based on a novel recombinant large hepatitis delta antigen that can detect anti-HDV in a concentration-dependent manner with pan-genotypic activity across all known HDV genotypes. We evaluated the performance of this test on a cohort of 474 patient samples and found that it has a sensitivity of 94.6% (314/332) and a specificity of 100% (142/142) when compared to a diagnostic gold-standard ELISA. It also works robustly for a broad range of anti-HDV titers. We anticipate this novel HDV rapid test to be an important tool for epidemiological studies and clinical diagnostics, especially in regions that currently lack access to reliable HDV testing.

Comparison of anti-hepatitis D virus (HDV) ETI-AB-DELTAK-2 assay and the novel LIAISON® XL MUREX anti-HDV assay in the diagnosis of HDV infection.

Hepatitis B/D virus infection leads to severe liver disease. HDV infection is not routinely investigated since the diagnosis is based on enzyme immunoassays (EIAs), which are not available in all laboratories. This study investigates the performance of new automated assay for anti HDV Ab detection: LIAISON® XL Murex anti-HDV. HBsAg-positive samples were evaluated for HDV serology using the ETI-AB-DELTAK-2 and the new LIAISON® XL Murex with a concordance of 97.5% and 2.42% discordant results. The discordant specimens reacted negatively with EIA and positively with the new test. Dilutions of HDV-purified antibodies and HDV-positive samples were tested with both assays, showing a lower detection limit for the new assay. In conclusion, LIAISON® XL Murex showed a good concordance with the reference method and allowed a more rapid HDV detection. This new diagnostic tool may be useful for a more efficient approach to the HDV diagnosis and evaluation of HDV epidemiology.

Evolutionary trends in the prevalence of anti-HDV antibodies among patients positive for HBsAg referred to a national laboratory in Cameroon from 2012 to 2017.

OBJECTIVE: The aim of this study was to update the data on the prevalence of anti-HDV antibodies in Cameroon. RESULTS: Antibodies against hepatitis Delta virus (Anti-HDV) were found in 16.48% (95% CI 11.46-18.77%) of 426 hepatitis B virus surface antigen positive patients in Cameroon. Remarkably, they were significantly higher among people over 40 years and those living in the East and South regions of Cameroon at 66.7%, 50%, and 40%, respectively. These results suggest that older age and living in areas in the dense forest may be risk factors for Hepatitis D infection.

Anti-HDV seroprevalance among patients with previous HBV infection.

OBJECTIVE: This prospective study aimed to determine the prevalence of anti-HDV seropositivity among subjects who had previous hepatitis B virus (HBV) infection. METHODS: Subjects who were admitted to the gastroenterology inpatient clinic of our hospital between August 2016 and July 2017 were screened for previous HBV infection. The subjects who had HBV serology compatible with resolved HBV infection were recruited in the study, and the seroprevalance of anti-HDV was studied. Participants answered a short questionnaire regarding their family history of chronic hepatitis B (CHB) and chronic hepatitis D (CHD) infection and risk factors for transmission. Subjects who were anti-HDV positive were recalled for a control visit, and HBV-DNA and HDV-RNA were assayed in the blood samples of the responders. RESULTS: Among 554 subjects who had previous HBV infection, 53 (9.6%) were anti-HDV positive. The mean age was 63.1±15.4 years in the anti-HDV-positive group and 65.9±15.6 years in the anti-HDV-negative group (p=0.19). The most common risk factor for both groups was dental procedures (89% vs 80%, p=0.33). Anti-Hbc IgG, anti-Hbs, and anti-HBeAg seropositivity did not differ between the anti-HDV-positive and -negative groups (for all, p>0.05). Although HDV-RNA was not detectable in all studied samples, only one subject had detectable HBV-DNA in the anti-HDV-positive group. CONCLUSION: This study highlighted the prevalence of anti-HDV among subjects who had resolved HBV infection. Long-term follow-up studies, including after the resolution of both infections, are needed to explore HBV-HDV interactions and the behavioral patterns of these viruses.

Hepatitis delta prevalence in South America: a systematic review and meta-analysis

Abstract Hepatitis delta virus (HDV) has been associated with acute or chronic hepatitis in Latin America, but there is no prevalence study covering South American countries. This meta-analysis aimed to estimate anti-HDV prevalence through a systematic review of published articles in English, Portuguese and Spanish until December 2017. Searches were conducted in Health Virtual Library, Capes, Lilacs, PubMed, and SciELO, according to defined criteria regarding participant selection and geographical setting. Study quality was assessed using the GRADE guidelines. Pooled anti-HDV prevalence was calculated using the DerSimonian-Laird random-effects model with Freeman-Tukey double arcsine transformation. Out of the 405 identified articles, only 31 met the eligibility criteria for inclusion in the meta-analysis. In South America, pooled anti-HDV prevalence among hepatitis B virus carriers was 22.37% (95% confidence interval: 13.72-32.26), though it appeared less frequently in some countries and populations, according to the data collection date. The findings indicated significant successive reductions in anti-HDV prevalence over thirty years. However, there was a scarcity of HDV epidemiological studies outside the Amazon Basin, notably in the Southwest continent and absence of target population standardization. There was a high HDV prevalence in South American countries, despite differences in methodological characteristics and outcomes, highlighting a drastic decline in the last decades. Future studies should identify HDV prevalence estimates in other regions of the continent and identify risk factors.

Lamivudine-resistant HBV strain rtM204V/I in acute hepatitis B.

AIMS: To detect HBV rtM204V/I lamivudine-resistant strains in serum of patients with acute hepatitis B and to assess their biological and clinical significance. METHODS: Eighty HBV DNA-positive patients with symptomatic acute hepatitis B observed from 1999 to 2010 were enrolled. A plasma sample obtained at the first observation was tested for HBV mutants in the polymerase region by direct sequencing; the antiviral drug-resistant rtM204V/I mutations, the most frequent HBV mutants in Italy, were also sought by the more sensitive allele-specific polymerase chain reaction (PCR). RESULTS: No HBV mutation associated with resistance to nucleos(t)ide analogues was identified by direct sequencing, whereas allele-specific PCR identified HBV strains carrying the substitution rtM204V/I in 11 (13.7%) patients. Compared with those with the HBV wild strain, patients with rtM204V/I more frequently showed severe acute hepatitis B (36.4% vs 8.7%; p < 0.05) and lower values of serum HBV DNA (1.77 × 10(6) ± 4.76 × 10(6) vs. 1.68 × 10(8) ± 5.46 × 10(8)). In addition, a multivariate analysis identified the presence of a pre-existing HCV chronic infection as independently associated with severe acute hepatitis B (p < 0.05). CONCLUSIONS: HBV rtM204V/I lamivudine-resistant strains were detected in serum of 11 (13.7%) patients with acute hepatitis B by allele-specific polymerase chain reaction. The frequent association of rtM204V/I with a more severe acute hepatitis B and with a lower viral load may suggest that greater and/or more prolonged immune pressure might have induced their selection.