Effect of Peg-IFN on the viral kinetics of patients with HDV infection treated with bulevirtide.

Background & Aims: Bulevirtide is a first-in-class entry inhibitor antiviral treatment for chronic hepatitis D. The viral kinetics during bulevirtide therapy and the effect of combining bulevirtide with pegylated-interferon (Peg-IFN) are unknown. Methods: We used mathematical modelling to analyze the viral kinetics in two French observational cohorts of 183 patients receiving bulevirtide with or without Peg-IFN for 48 weeks. Results: The efficacy of bulevirtide in blocking cell infection was estimated to 90.3%, whereas Peg-IFN blocked viral production with an efficacy of 92.4%, albeit with large inter-individual variabilities. The addition of Peg-IFN to bulevirtide was associated with a more rapid virological decline, with a rate of virological response (>2 log of decline or undetectability) at week 48 of 86.9% (95% prediction interval [PI] = [79.7-95.0]), compared with 56.1% (95% PI = [46.4-66.7]) with bulevirtide only. The model was also used to predict the probability to achieve a cure of viral infection, with a rate of 8.8% (95% PI = [3.5-13.2]) with bulevirtide compared with 18.8% (95% PI = [11.6-29.0]) with bulevirtide + Peg-IFN. Mathematical modelling suggests that after 144 weeks of treatment, the rates of viral cure could be 42.1% (95% PI = [33.3-52.6]) with bulevirtide and 66.7% (95% PI = [56.5-76.8]) with bulevirtide + Peg-IFN. Conclusions: In this analysis of real-world data, Peg-IFN strongly enhanced the kinetics of viral decline in patients treated with bulevirtide. Randomized clinical trials are warranted to assess the virological and clinical benefit of this combination, and to identify predictors of poor response to treatment. Impact and implications: Bulevirtide has been approved for chronic HDV infection by regulatory agencies in Europe based on its good safety profile and rapid virological response after treatment initiation, but the optimal duration of treatment and the chance to achieve a sustained virological response remain unknown. The results presented in this study have a high impact for clinicians and investigators as they provide important knowledge on the long-term virological benefits of a combination of Peg-IFN and bulevirtide in patients with CHD. Clinical trials are now warranted to confirm those predictions.

Treatment with bulevirtide in HIV-infected patients with chronic hepatitis D: ANRS HD EP01 BuleDelta and compassionate cohort.

Background & Aims: In France, bulevirtide (BLV) became available in September 2019 through an early access program to treat patients with HDV. The aim of this analysis was to evaluate the efficacy and safety of BLV in patients with HIV and HDV coinfection. Methods: Patients received BLV 2 mg ± pegylated interferon-α (pegIFNα) according to the physician's decision. The primary endpoint (per-protocol analysis) was the virological response rate at Week 48, defined as the proportion of patients with undetectable serum HDV RNA or a HDV RNA decline >2 log10 IU/ml from baseline. Results: The characteristics of the 38 patients were as follows: 28 male, mean age 47.7 years, and mean baseline HDV RNA viral load 5.7 ± 1.2 log10 IU/ml. Median HIV viral load and mean CD4 count were 32 (30-65) copies/ml and 566 ± 307/mm3, respectively. Eight patients stopped treatment before Week 48. At Week 48, 10 of 19 patients (52.6%) in the 2 mg BLV group and five of seven patients (71.4%) in the 2 mg BLV + pegIFNɑ group had reached virological response (no HDV RNA available in four patients). At Week 48, seven of 19 patients in the 2 mg BLV group and three of six patients in the 2 mg BLV + pegIFNɑ group had a combined response (virological response and normal alanine aminotransferase level). Conclusions: Adults living with HIV coinfected with HDV can be treated by BLV with a virological response in more than 50% of patients. The combination of BLV and pegIFNɑ showed a strong virological response. Impact and implications: Bulevirtide is the only EMA-approved drug for HDV treatment, and we showed that it can be used in adults living with HIV, with an overall good tolerability. Bulevirtide induces a virological response in more than 50% of patients, suggesting that bulevirtide should be considered as a first-line therapy in this specific population. Bulevirtide in combination with pegIFNα could be used in patients without pegIFNα contraindication. No specific drug-drug interaction is reported. Bulevirtide is the only EMA-approved drug for HDV treatment, and we showed that it can be used in adults living with HIV, with an overall good tolerability. Bulevirtide induces a virological response in more than 50% of patients, suggesting that bulevirtide should be considered as a first-line therapy in this specific population. Bulevirtide in combination with pegIFNα could be used in patients without pegIFNα contraindication. No specific drug-drug interaction is reported. Bulevirtide is the only EMA-approved drug for HDV treatment, and we showed that it can be used in adults living with HIV, with an overall good tolerability. Bulevirtide induces a virological response in more than 50% of patients, suggesting that bulevirtide should be considered as a first-line therapy in this specific population. Bulevirtide in combination with pegIFNα could be used in patients without pegIFNα contraindication. No specific drug-drug interaction is reported.

HDV RNA assays: Performance characteristics, clinical utility, and challenges.

Coinfection with HBV and HDV results in hepatitis D, the most severe form of chronic viral hepatitis, frequently leading to liver decompensation and HCC. Pegylated interferon alpha, the only treatment option for chronic hepatitis D for many years, has limited efficacy. New treatments are in advanced clinical development, with one recent approval. Diagnosis and antiviral treatment response monitoring are based on detection and quantification of HDV RNA. However, the development of reliable HDV RNA assays is challenged by viral heterogeneity (at least 8 different genotypes and several subgenotypes), intrahost viral diversity, rapid viral evolution, and distinct secondary structure features of HDV RNA. Different RNA extraction methodologies, primer/probe design for nucleic acid tests, lack of automation, and overall dearth of standardization across testing laboratories contribute to substantial variability in performance characteristics of research-based and commercial HDV RNA assays. A World Health Organization (WHO) standard for HDV RNA, available for about 10 years, has been used by many laboratories to determine the limit of detection of their assays and facilitates comparisons of RNA levels across study centers. Here we review challenges for robust pan genotype HDV RNA quantification, discuss particular clinical needs and the importance of reliable HDV RNA quantification in the context of drug development and patient monitoring. We summarize distinct technical features and performance characteristics of available HDV RNA assays. Finally, we provide considerations for the use of HDV RNA assays in the context of drug development and patient monitoring.

HIV-1 infection in South Kivu (Democratic Republic of Congo): high genotypic resistance to antiretrovirals.

BACKGROUND: Panzi General Reference Hospital (HGR Panzi) in the Democratic Republic of Congo follows a large number of patients living with HIV-1 (PLWHIV). Although antiretrovirals (ARVs) are available, HIV-1 viral load (HIV-VL) measurement has only been implemented in the hospital since 2018. No data on ARV resistance levels and ARV dosage in plasma have yet been published for this region. We determined the prevalence of virological failure due to ARV resistance amongst patients and assessed the degree of genotypic resistance of the viral strains. METHODS: We performed an HIV-VL test and determined dosage of ARVs on samples collected from 205 PLWHIV at HGR Panzi between 2017 and 2018, including 13 ARV-naive patients. Genotypic resistance testing was performed on all samples with detectable HIV-VLs, and interpreted with the Agence Nationale de Recherches sur le Sida (ANRS) 2018 algorithm. RESULTS: Baseline resistance to NNRTIs was found in 2 of the 13 treatment-naive individuals (15%). ARV dosage was non-optimal for 44/192 of treated patients (22.9%), with an HIV-VL ≥1000 IU/mL for 40/192 (20.8%) of them. In particular, treatment-experienced viruses presented resistance to at least one NRTI (52.5%), to at least one NNRTIs (70%) or to at least one PIs (15%). Finally, two samples contained viruses with resistance polymorphism in the integrase gene. CONCLUSIONS: The high level of resistance to ARVs observed during this study, mainly due to treatment compliance default, fully justifies the implementation of means for closer patient monitoring. The provision of VL tests and therapeutic education management tools in a PLWHIV follow-up remains an absolute necessity to best adapt the current treatment lines in this region.

Clinical and virological features of chronic hepatitis B in the French national surveillance program, 2008-2012: A cross-sectional study.

Background & Aims: Among people living with HBV, only a subset of individuals with chronic hepatitis is in need of treatment, and this proportion varies according to the population, region, and setting. No estimates of the proportion of people who are infected with HBV and meet the treatment eligibility criteria in France are available. Methods: 552 treatment-naïve individuals with chronic HBV infection referred for the first time to a hepatology reference centre between 2008 and 2012 were prospectively included. Demographic, clinical, and laboratory data were analysed. Results: In total, 61.1% of patients were males, with a median age of 37.5 years. Moreover, 64% were born in an intermediate- or high-HBV endemicity country, and 90% were HBeAg-negative. At referral, median HBV DNA and HBsAg levels were 3.3 and 3.6 log IU/ml, respectively; 37.8% of patients had alanine aminotransferase >40 U/L, and 29.0% had moderate or severe fibrosis (≥F2), including 9.4% with cirrhosis. The most prevalent genotypes were D (34.7%), E (27.4%), and A (25.7%). Coinfections were rare: 2.4% were HIV-positive, 4.0% were HCV-positive, and 6.0% were HDV-positive. According to the 2017 EASL Clinical Practice Guidelines, using a single time point analysis, 2.7% of patients were classified as HBeAg-positive chronic infection, 6.1% as HBeAg-positive chronic hepatitis B, 26.5% as HBeAg-negative chronic hepatitis B, and 61.1% as HBeAg-negative chronic infection, whereas 3.6% patients could not be classified. The performance of HBsAg level quantification to identify individuals with HBeAg-negative chronic hepatitis B was poor. A total of 29.1% met the criteria for initiation of antiviral treatment, whereas 66.5% remained under routine clinical surveillance. Most eligible patients initiated recommended first-line therapies, including tenofovir (45.3%), entecavir (36.8%), or pegylated interferon alpha (11.6%). Conclusions: Of all cases, 9.4% had cirrhosis at presentation and 29.1% met the 2017 EASL Clinical Practice Guidelines treatment criteria. HBsAg levels failed to accurately identify individuals with HBeAg-negative chronic infection. Lay summary: Among French adults chronically infected with HBV referred for the first time to hepatology reference centres, about one-third had a significant liver disease. Approximately one-third of individuals met criteria for initiation of antiviral treatment based on entecavir or tenofovir or, occasionally, pegylated interferon alpha.

Hepatitis B, C, and delta in the general population in Mayotte: hepatitis B as a major public health concern.

BACKGROUND: Located in southwestern Indian Ocean, Mayotte is a French territory, with a very specific demographic, social and health context. To date, epidemiological data on infections by hepatitis B (HBV), C (HCV), and delta (HDV) viruses in Mayotte have been sparse. We aimed to estimate, in the 15-69-year-old general population living in Mayotte, the prevalence of infections by hepatitis B (HBV), C (HCV), and delta (HDV) viruses and the distribution of HBV status: current infection with positive HBs antigen (Ag); resolved infection with positive HBc antibodies and negative HBsAg; immunisation by vaccination with only positive HBs antibodies; and no infection/no immunisation with negative markers. We also described the characteristics of infected people and assessed the determinants of lifetime HBV infection. METHODS: The Unono Wa Maore survey, implemented in a random sample of the general population in 2018-2019, consisted of an at-home collection of epidemiological data and venous blood samples. Detection of hepatitis B, C, and delta serological and molecular markers was performed. RESULTS: Among 5207 eligible people, 4643 responded to the questionnaire (89.2%), with 2917 being tested for HBV and HCV (62.8%). Estimated HBV status was as follows: current infection 3.0% (95% confidence interval [CI]: 2.3-3.9%) (n = 76); resolved infection 27.8% (95% CI: 25.8-29.9); immunisation by vaccination 27.7% (95% CI: 25.9-29.7); and no infection/no immunisation 41.5% (95% CI: 39.3-43.7). One participant was positive for HDV antibodies (Ab) (0.65%) with a negative HDV-RNA viral load. The risk of lifetime HBV infection was higher in men (adjusted prevalence ratio (aPR): 1.55, 95% CI: 1.29-1.89); in people aged 30-49 years (aPR: 3.83, 95% CI: 1.49-9.81) or 50-69 years (aPR: 4.52, 95% CI: 1.77-11.53) compared to those under 20; in individuals who reported no condom use during their first sexual intercourse (aPR: 1.46, 95% CI: 1.01-2.14); and in those living in Dembeni-Mamoudzou (aPR: 1.40, 95% CI: 1.09-1.80) compared to the West-Centre of Mayotte. Finally, six individuals were positive for HCV antibodies (0.21%), including three positive for HCV RNA. CONCLUSIONS: Mayotte is an area of intermediate endemicity for HBV and low endemicity for HCV and HDV. With a prevalence of HBsAg 10 times higher than in mainland France, a high proportion of people susceptible to HBV infection, and a demographic, health, and social context that may favour its transmission, hepatitis B is a major public health concern in Mayotte.

Comprehensive Analysis of Hepatitis Delta Virus Assembly Determinants According to Genotypes: Lessons From a Study of 526 Hepatitis Delta Virus Clinical Strains.

Human hepatitis Delta virus (HDV) infection is associated to the most severe viral hepatic disease, including severe acute liver decompensation and progression to cirrhosis, and hepatocellular carcinoma. HDV is a satellite of hepatitis B virus (HBV) that requires the HBV envelope proteins for assembly of HDV virions. HDV and HBV exhibit a large genetic diversity that extends, respectively to eight (HDV-1 to -8) and to ten (HBV/A to/J) genotypes. Molecular determinants of HDV virion assembly consist of a C-terminal Proline-rich domain in the large Hepatitis Delta Antigen (HDAg) protein, also known as the Delta packaging domain (DPD) and of a Tryptophan-rich domain, the HDV matrix domain (HMD) in the C-terminal region of the HBV envelope proteins. In this study, we performed a systematic genotyping of HBV and HDV in a cohort 1,590 HDV-RNA-positive serum samples collected between 2001 to 2014, from patients originated from diverse parts of the world, thus reflecting a large genetic diversity. Among these samples, 526 HBV (HBV/A, B, C, D, E, and G) and HDV (HDV-1, 2, 3, and 5 to -8) genotype couples could be obtained. We provide results of a comprehensive analysis of the amino-acid sequence conservation within the HMD and structural and functional features of the DPD that may account for the yet optimal interactions between HDV and its helper HBV.

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.

Variable In Vivo Hepatitis D Virus (HDV) RNA Editing Rates According to the HDV Genotype.

Human hepatitis delta virus (HDV) is a small defective RNA satellite virus that requires hepatitis B virus (HBV) envelope proteins to form its own virions. The HDV genome possesses a single coding open reading frame (ORF), located on a replicative intermediate, the antigenome, encoding the small (s) and the large (L) isoforms of the delta antigen (s-HDAg and L-HDAg). The latter is produced following an editing process, changing the amber/stop codon on the s-HDAg-ORF into a tryptophan codon, allowing L-HDAg synthesis by the addition of 19 (or 20) C-terminal amino acids. The two delta proteins play different roles in the viral cell cycle: s-HDAg activates genome replication, while L-HDAg blocks replication and favors virion morphogenesis and propagation. L-HDAg has also been involved in HDV pathogenicity. Understanding the kinetics of viral editing rates in vivo is key to unravel the biology of the virus and understand its spread and natural history. We developed and validated a new assay based on next-generation sequencing and aimed at quantifying HDV RNA editing in plasma. We analyzed plasma samples from 219 patients infected with different HDV genotypes and showed that HDV editing capacity strongly depends on the genotype of the strain.

Early virological response in six patients with hepatitis D virus infection and compensated cirrhosis treated with Bulevirtide in real-life.

Hepatitis delta virus (HDV) infection is the most severe form of viral hepatitis. Bulevirtide (BLV, Hepcludex® ) is an HDV/HBV entry inhibitor approved in June 2020 in the European Union for adult patients with chronic hepatitis delta (CHD) and compensated liver disease and positive HDV RNA viral load. This real-life preliminary report described early virological efficacy and safety of BLV in six patients with CHD and compensated liver disease: four patients were treated with the combination of BLV (2 mg/d in subcutaneous injection) and pegylated interferon (PEG-IFN) and two patients with BLV monotherapy. Four patients treated with combined therapy had a decline of a minimum of 1 log10 and 3/3 of 2 log10 of HDV-VL at 12 and 24 weeks, respectively. One patient among four had stopped the treatment at 12 weeks because of thrombocytopenia and an HDV-VL relapse was notified 24 weeks after treatment cessation. Three patients among four (3/4) had undetectable HDV-VL during the therapy (<100 IU/ml). One patient (1/2) treated with BLV monotherapy had a decline of HDV-VL by 1 log10 at 8 weeks and 1/1 by 2 log10 at 28 week on-treatment. Two patients among four (2/4) with combined therapy had normal ALT reached at 4 and 56 weeks. One patient (1/2) with BLV monotherapy achieves ALT normalization at​ 4 weeks on treatment. Hepatitis B surface antigen (HBsAg) levels remain unchanged. Three among six (3/6) patients had an elevation of total biliary acids without pruritus. These early data generated confirm the interest in this new treatment. Final results will be important to demonstrate long-term clinical benefit (fibrosis reversibility and reduction in hepato-cellular carcinoma [HCC]).

Performance of 30 commercial SARS-CoV-2 serology assays in testing symptomatic COVID-19 patients.

We report evaluation of 30 assays' (17 rapid tests (RDTs) and 13 automated/manual ELISA/CLIA assay (IAs)) clinical performances with 2594 sera collected from symptomatic patients with positive SARS-CoV-2 rRT-PCR on a respiratory sample, and 1996 pre-epidemic serum samples expected to be negative. Only 4 RDT and 3 IAs fitted both specificity (> 98%) and sensitivity (> 90%) criteria according to French recommendations. Serology may offer valuable information during COVID-19 pandemic, but inconsistent performances observed among the 30 commercial assays evaluated, which underlines the importance of independent evaluation before clinical implementation.

Origin, HDV genotype and persistent viremia determine outcome and treatment response in patients with chronic hepatitis delta.

BACKGROUND & AIMS: HDV infection causes severe chronic liver disease in individuals infected with HBV. However, the factors associated with poor prognosis are largely unknown. Thus, we aimed to identify prognostic factors in patients with HDV infection. METHODS: The French National Reference Centre for HDV performed a nationwide retrospective study on 1,112 HDV-infected patients, collecting epidemiological, clinical, virological and histological data from the initial referral to the last recorded follow-up. RESULTS: The median age of our cohort was 36.5 (29.9-43.2) years and 68.6% of our cohort were male. Most patients whose birthplace was known were immigrants from sub-Saharan Africa (52.5%), southern and eastern Europe (21.3%), northern Africa and the Middle East (6.2%), Asia (5.9%) and South America (0.3%). Only 150 patients (13.8%) were French native. HDV load was positive in 659 of 748 tested patients (88.1%). HDV-1 was predominant (75.9%), followed by sub-Saharan genotypes: HDV-5 (17.6%), HDV-7 (2.9%), HDV-6 (1.8%) and HDV-8 (1.6%). At referral, 312 patients (28.2%) had cirrhosis, half having experienced at least 1 episode of hepatic decompensation. Cirrhosis was significantly less frequent in African than in European patients regardless of HDV genotype. At the end of follow-up (median 3.0 [0.8-7.2] years), 48.8% of the patients had developed cirrhosis, 24.2% had ≥1 episode(s) of decompensation and 9.2% had hepatocellular carcinoma. European HDV-1 and African HDV-5 patients were more at risk of developing cirrhosis. Persistent replicative HDV infection was associated with decompensation, hepatocellular carcinoma and death. African patients displayed better response to interferon therapy than non-African patients (46.4% vs. 29.1%, p <0.001). HDV viral load at baseline was significantly lower in responders than in non-responders. CONCLUSION: Place of birth, HDV genotype and persistent viremia constitute the main determinants of liver involvement and response to treatment in chronic HDV-infected patients. LAY SUMMARY: Chronic liver infection by hepatitis delta virus (HDV) is the most severe form of chronic viral hepatitis. Despite the fact that at least 15-20 million people are chronically infected by HDV worldwide, factors determining the severity of liver involvement are largely unknown. By investigating a large cohort of 1,112 HDV-infected patients followed-up in France, but coming from different areas of the world, we were able to determine that HDV genotype, place of birth (reflecting both viral and host-related factors) and persistent viremia constitute the main determinants of liver involvement and response to treatment.

Characterization of hepatitis delta virus strains spreading in Abuja, Nigeria.

Hepatitis delta virus (HDV) is responsible for the most severe form of liver disease in humans. So far, eight genotypes (HDV-1 to -8) have been individualized worldwide. Little is known about HDV strains that spread in Nigeria. HDV genotyping was performed in 15 anti-HDV positive samples from a cohort of 306 hepatitis B virus (HBV)-infected patients in Abuja (Nigeria). Phylogenetic analyses revealed 90% were HDV-1, two among them clustering with European/Asian HDV-1, the remaining one being HDV-6. It was also found that two members of a couple superinfected with the same HDV strain, were enveloped by two different HBV strains of genotype E.

Hepatitis B virus and hepatitis delta virus subtypes circulating in Algeria and seroprevalence of HDV infection.

BACKGROUND: Little is known about molecular characteristics of HBV strains circulating in Algeria and there are few data regarding HDV infection. OBJECTIVES: The aim of this study is to describe the genetic diversity of HBV and HDV strains existing in Algeria and to determine the seroprevalence of HDV infection. STUDY DESIGN: Plasma samples from 134 patients were analyzed by enzyme immunoassay method for HBV and HDV serological markers. Genotyping of HBV and HDV strains were performed using direct sequencing followed by phylogenetic analyses of the PreS1 and R0 region of the HBV and HDV genome respectively. RESULTS: The PreS1 gene was successfully amplified in 119 patients (82 males and 37 females). Phylogenetic analysis of HBV strains revealed the presence of genotypes D (86.5%) and A2 (11.76%). The subgenotypes D are distributed as follows: HBV/D7 (43.5%), HBV/D3 (24.75%), HBV/D1 (16.8%) and HBV/D2 (14.85%). A recombinant between genotypes A, E and D was found. The seroprevalence of HDV infection among HBV carriers was less than 5.35%. Only one isolate of HDV genotype 1 was identified. CONCLUSIONS: Our data indicate the predominance of HBV subgenotype D7 and a low prevalence of HDV infection.

Hepatitis B and hepatitis D virus infections in the Central African Republic, twenty-five years after a fulminant hepatitis outbreak, indicate continuing spread in asymptomatic young adults.

Hepatitis delta virus (HDV) increases morbidity in Hepatitis B virus (HBV)-infected patients. In the mid-eighties, an outbreak of HDV fulminant hepatitis (FH) in the Central African Republic (CAR) killed 88% of patients hospitalized in Bangui. We evaluated infections with HBV and HDV among students and pregnant women, 25 years after the fulminant hepatitis (FH) outbreak to determine (i) the prevalence of HBV and HDV infection in this population, (ii) the clinical risk factors for HBV and/or HDV infections, and (iii) to characterize and compare the strains from the FH outbreak in the 1980s to the 2010 HBV-HDV strains. We performed a cross sectional study with historical comparison on FH-stored samples (n = 179) from 159 patients and dried blood-spots from volunteer students and pregnant women groups (n = 2172). We analyzed risk factors potentially associated with HBV and HDV. Previous HBV infection (presence of anti-HBc) occurred in 345/1290 students (26.7%) and 186/870 pregnant women (21.4%)(p = 0.005), including 110 students (8.8%) and 71 pregnant women (8.2%), who were also HBsAg-positive (p = 0.824). HDV infection occurred more frequently in pregnant women (n = 13; 18.8%) than students (n = 6; 5.4%) (p = 0.010). Infection in childhood was probably the main HBV risk factor. The risk factors for HDV infection were age (p = 0.040), transfusion (p = 0.039), and a tendency for tattooing (p = 0.055) and absence of condom use (p = 0.049). HBV-E and HDV-1 were highly prevalent during both the FH outbreak and the 2010 screening project. For historical samples, due to storage conditions and despite several attempts, we could only obtain partial HDV amplification representing 25% of the full-length genome. The HDV-1 mid-eighties FH-strains did not form a specific clade and were affiliated to two different HDV-1 African subgenotypes, one of which also includes the 2010 HDV-1 strains. In the Central African Republic, these findings indicate a high prevalence of previous and current HBV-E and HDV-1 infections both in the mid-eighties fulminant hepatitis outbreak and among asymptomatic young adults in 2010, and reinforce the need for universal HBV vaccination and the prevention of HDV transmission among HBsAg-positive patients through blood or sexual routes.

Molecular characterization of the full-length genome sequences of HDV strains circulating in Tunisia.

While Tunisia is endemic for hepatitis B virus (HBV), a recent large-scale retrospective study, revealed a very low prevalence (2%) of hepatitis Delta virus (HDV) (Yacoubi et al. in J Clin Virol 72:126-132, 2015). All strains were classified within the genotype 1 (HDV-1) as assessed by nucleotide sequencing of the so-called 'R0' region of the genome described previously. In this study, we aimed to determine the full-length genome sequence of HDV isolates in order to fully characterize the HDV strains spreading in Tunisia. Eleven HDV antibody and RNA positive samples were obtained from the 1615 clinical samples previously studied. The whole genome sequence was obtained for 5 strains by sequencing and realignment of four overlapping regions covering the entire genome, followed by extensive phylogenetic analyses. Tunisian sequences segregated together with Turkish and African sequences and showed 60% GC content. Alignment with an HDV-1 consensus sequence revealed that they exhibited several point mutations in different functional domains of the delta proteins that, according to previous studies, might possibly affect their properties. In conclusion, the first full-length genome sequences of Tunisian HDV isolates are provided, isolates which are closely related to Turkish and Sub-Saharan Africa strains, supporting the hypothesis for the spread of HDV-1-strains from Africa via Tunisia to Turkey, before spread to the rest of the world.