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.

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.

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.

Genetic diversity and worldwide distribution of the deltavirus genus: A study of 2,152 clinical strains.

Hepatitis delta virus (HDV) is responsible for the most severe form of acute and chronic viral hepatitis. We previously proposed that the Deltavirus genus is composed of eight major clades. However, few sequences were available to confirm this classification. Moreover, little is known about the structural and functional consequences of HDV variability. One practical consequence is the failure of most quantification assays to properly detect or quantify plasmatic HDV RNA. Between 2001 and 2014, 2,152 HDV strains were prospectively collected and genotyped in our reference laboratory by means of nucleotide sequencing and extensive phylogenetic analyses of a 400-nucleotide region of the genome (R0) from nucleotides 889 to 1289 encompassing the 3' end of the delta protein-coding gene. In addition, the full-length genome sequence was generated for 116 strains selected from the different clusters, allowing for in-depth characterization of the HDV genotypes and subgenotypes. This study confirms that the HDV genus is composed of eight genotypes (HDV-1 to HDV-8) defined by an intergenotype similarity >85% or >80%, according to the partial or full-length genome sequence, respectively. Furthermore, genotypes can be segregated into two to four subgenotypes, characterized by an intersubgenotype similarity >90% (>84% for HDV-1) over the whole genome sequence. Systematic analysis of genome and protein sequences revealed highly conserved functional nucleotide and amino acid motifs and positions across all (sub)genotypes, indicating strong conservatory constraints on the structure and function of the genome and the protein. CONCLUSION: This study provides insight into the genetic diversity of HDV and a clear view of its geographical localization and allows speculation as to the worldwide spread of the virus, very likely from an initial African origin. (Hepatology 2017;66:1826-1841).

Hepatitis delta virus infection in a large cohort of chronic hepatitis B patients in Ethiopia.

BACKGROUND & AIMS: Hepatitis D virus (HDV) infection is associated with a more severe outcome in patients with chronic hepatitis B (CHB); however, little is known about the presence of HDV in sub-Saharan Africa. We aimed to determine the prevalence of HDV infection, as well as its clinical, biological and virological characteristics, in a large CHB cohort in Ethiopia. METHODS: In total, 1267 HIV-negative CHB patients at St. Paul's Hospital Millennium Medical College in Addis Ababa were screened for anti-HDV antibodies using ELISA assays. Confirmed positive samples were further tested for HDV RNA using a consensus commercial real-time RT-PCR assay. HDV genotypes were also determined for RNA-positive samples by nucleotide sequencing followed by phylogenetic analyses. Demographical, clinical and biological data from patients were recorded and compared based on HDV RNA results. RESULTS: Most patients (n = 748, 59.0%) were men, and the median age was 31 years (interquartile range 26-40). Anti-HDV antibodies were detected in 19 individuals (1.5%), 12 of whom were HDV RNA-positive with a viral load ranging from <2 to >8 log 10 IU/mL. All strains were genotype 1. HDV RNA-positive patients were more likely to have significant liver fibrosis (63.6% vs 24.7%, P = .007) and cirrhosis (45.5% vs 16.4%, P = .024). CONCLUSIONS: HDV infection is rare in Ethiopia but is associated with more advanced liver fibrosis.

Hepatitis B Virus-Hepatitis D Virus mother-to-child co-transmission: A retrospective study in a developed country.

BACKGROUND & AIMS: Hepatitis B Virus (HBV) DNA during chronic infection can reach levels at which mother-to-child (MTC) transmission frequently occurs despite passive-active immunization of newborns. Hepatitis D Virus (HDV) RNA can reach high levels, we assessed HBV/HDV MTC co-transmission. METHODS: Monocentric retrospective study (registered in ClinicalTrials.gov (NCT02044055)), after informed consent in HBV/HDV co-infected women pregnant between 01/01/2004 and 01/01/2015 in Paris, France. The children were tested when 24 months of age or older. RESULTS: Twenty-two (3%) of 742 HBV infected women, HDV co-infected, gave birth to 54 children during the study period. HBV DNA was above 5 Log10 I.U/mL in 10 pregnancies previous any treatment, with HDV RNA of less than 2.3 Log10 I.U/mL. HDV RNA was above 5 Log10 I.U/mL in eight pregnancies previous any treatment, with HBV DNA of less than 1.5 Log10 I.U/mL. Inverse patterns of HBV DNA and HDV RNA were observed in 17 of 35 (49%) pregnancies: 13 (76%) received no HBV treatment; four (24%) were treated. HBV DNA was under 5 Log10 I.U/mL in 46 of the 50 assessed women (92%) at birth. Of the 36 assessed children, given passive-active immunization, 24 (66%) were protected, 10 (28%) were neither infected nor protected, one was chronically HBV infected, and one had a past HBV infection. HDV Ab was negative in the 36 children. CONCLUSIONS: These results suggest that HBV/HDV MTC co-transmission is exceptional. Studies are needed, mainly in developing countries.

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.

Performance Characteristics of a New Consensus Commercial Kit for Hepatitis D Virus RNA Viral Load Quantification.

Hepatitis D virus (HDV) is responsible for fulminant hepatitis and liver failure and accelerates evolution toward cirrhosis and hepatocellular carcinoma in hepatitis B virus (HBV)-infected patients. To date, treatment relies upon long-term administration of pegylated alpha-interferon with a sustained virological response in 30% of the patients. Very recently, new, promising anti-HDV therapies have been developed and are already being used in clinical trials. HDV RNA viral load (HDVL) monitoring must be an integral part of the management of the infected patients. However, HDV genus is characterized by a high genetic variability into eight genotypes (HDV-1 to -8), and most available in-house or commercial assays are useful for only a limited subset of genotypes. Results of a comparison of the performance of a new kit for HDVL quantification with the consensus in-house assay of the French National Reference Laboratory for HDV developed in 2005 are reported here. A total of 611 clinical samples of all HDV genotypes with various HDVL values, including several consecutive samples over several years from 36 patients, were studied. A specificity, sensitivity, and reproducibility evaluation was conducted using HDV-positive clinical samples, hepatitis A, B, C and E (HAV, HBV, HCV, and HEV, respectively) and HIV mono-infected samples, and the WHO HDV RNA international standard. Overall results were strictly comparable between the two assays (median difference, 0.07 log IU/ml), with high diagnosis precision and capacity. In summary, this new kit showed high performance in detection/quantification of HDVL, regardless of the genotype of the infecting strain used, and seems to be a suitable tool for patient management.

First international external quality assessment for hepatitis delta virus RNA quantification in plasma.

Infection by the hepatitis delta virus (HDV), a satellite of the hepatitis B virus (HBV), increases viral liver disease severity. Its diagnosis is thus vital for HBV-infected patients. HDV-RNA load (HDVL) should be assessed and monitored in plasma using real-time reverse-transcriptase polymerase chain reaction assays. Taking advantage of the recently-developed World Health Organization (WHO) HDV international standard (WHO-HDV-IS), the first international external quality control for HDVL quantification was performed. Two panels of samples were sent to 28 laboratories in 17 countries worldwide. Panel A comprised 20 clinical samples of various genotypes (1, 2, and 5-8) and viral loads, including two negative controls. Panel B, composed of dilutions of the WHO-HDV-IS, allowed the conversion of results from copies/mL into IU/mL for HDVL standardization and interlaboratory comparisons. Comprehensive analysis revealed a very high heterogeneity of assay characteristics, including their technical steps and technologies. Thirteen labs (46.3%) properly quantified all 18 positive samples; 16 (57.1%) failed to detect one to up to 10 samples, and several others underestimated (>3 log IU/mL) HDVL of African genotype strains (1 and 5-8). Discrepancies were mainly attributed to either primers or probe mismatches related to the high genetic variability of HDV and, possibly, to the complex secondary structure of the target genomic RNA. The labs were grouped in four clusters by the statistical analysis of their performances. The best clusters comprised the 17 labs that obtained the expected HDVL values, including five that otherwise failed to quantify one or two samples. CONCLUSION: The results of this international quality-control study underline the urgent need to improve methods used to monitor HDV viremia and will be instrumental in achieving that goal. (Hepatology 2016;64:1483-1494).

Infectious Zika virus in vaginal secretions from an HIV-infected woman, France, August 2016.

A woman with controlled HIV infection developed in late August 2016 a pruritic rash with fever and conjunctival hyperaemia after a trip to the French Caribbean islands. On day 3 after symptom onset, Zika virus RNA was detected in plasma, urine and vaginal samples with respective viral loads of 3.8, 6.1 and 5.3 log copies/mL. Notably, we demonstrated the presence of infectious Zika virus particles in the vaginal samples by isolation in cell culture.

Different precore/core mutations of hepatitis B interact with, limit, or favor liver fibrosis severity.

BACKGROUND AND AIM: The impact of basal core promoter (BCP) and precore (PC) mutants of the hepatitis B virus (HBV) on liver disease severity remains controversial. The aim of the present study was to screen BCP and PC mutations in 252 HBV surface antigen (HBsAg) positive carriers in France and to assess relationships between these mutations and severe fibrosis. METHODS: Direct sequencing of the precore/core gene was used to detect A1762T/G1764A and G1757A mutations in the BCP and G1896A and G1899A mutations in the PC region. RESULTS: The prevalences of A1762T/G1764A, G1757A, G1896A, and G1899A mutations were 34.1%, 38.7%, 54.9%, and 29.3% (P < 0.001), respectively. The independent predictors of severe fibrosis (≥F3 Metavir) were older age (P < 0.001), male gender (P = 0.012), elevated alanine aminotransferase (P < 0.001), and the double A1762T/G1764A mutant with no other mutations (P = 0.011). Interestingly, the association of the G1899A mutation with the double A1762T/G1764A mutant significantly counteracted the deleterious effect of the sole double A1762T/G1764A mutant (odds ratio [OR] = 0.28 vs. OR = 3.55, respectively, P = 0.028). CONCLUSIONS: Patients with the A1762T/G1764A mutation have a higher risk of severe fibrosis. The G1899A mutation is a protective factor against severe fibrosis that counteracted the deleterious effect of the A1762T/G1764A mutation. Finally, host phenotypic and HBV genotypic markers independently predict fibrosis severity.

Serological and molecular diagnosis of hepatitis delta virus infection: results of a French national quality control study.

A French national quality control study for the serological and molecular diagnosis of hepatitis delta virus (HDV) was organized. Total HDV antibodies were properly detected by all laboratories; 8/14 laboratories failed to detect low titers of IgM, and 6/11 failed to quantify and/or underestimated the RNA viral load in several samples. These discrepancies are likely related to the molecular diversity of HDV.

jpHMM: recombination analysis in viruses with circular genomes such as the hepatitis B virus.

jpHMM is a very accurate and widely used tool for recombination detection in genomic sequences of HIV-1. Here, we present an extension of jpHMM to analyze recombinations in viruses with circular genomes such as the hepatitis B virus (HBV). Sequence analysis of circular genomes is usually performed on linearized sequences using linear models. Since linear models are unable to model dependencies between nucleotides at the 5'- and 3'-end of a sequence, this can result in inaccurate predictions of recombination breakpoints and thus in incorrect classification of viruses with circular genomes. The proposed circular jpHMM takes into account the circularity of the genome and is not biased against recombination breakpoints close to the 5'- or 3'-end of the linearized version of the circular genome. It can be applied automatically to any query sequence without assuming a specific origin for the sequence coordinates. We apply the method to genomic sequences of HBV and visualize its output in a circular form. jpHMM is available online at http://jphmm.gobics.de for download and as a web server for HIV-1 and HBV sequences.

The Prevalence and Molecular Epidemiology of Hepatitis Delta Virus in Nigeria: The Results of a Nationwide Study.

Hepatitis delta virus (HDV) is a satellite of hepatitis B virus (HBV), which requires the HBV surface antigen (HBsAg) for its assembly and propagation. Although countries affected by HBV infection in Africa are well identified, data on HDV infection are still scarce, like in Nigeria, where HBV infection is endemic. In this study, we aimed to determine the prevalence of HDV infection and identify the circulating genotypes/strains in the country. A nationwide study was performed on 1281 HBsAg-positive samples collected from patients across eleven sites drawn from the six geopolitical zones in Nigeria. Anti-HDV antibody (HDV-Ab) screening and HDV-RNA viral load quantification were performed using a commercial ELISA assay and real-time RT-PCR kit, respectively. HDV genotyping was performed by the Sanger sequencing of amplicons from the so-called R0 region of the viral genome, followed by phylogenetic analyses. Of the 1281 HBsAg-positive samples, 61 (4.8%) were HDV-Ab positive, among which, 12 (19.7%) were HDV-RNA positive. Genotypes were obtained for nine of them: seven "African" HDV-1, one "Asian/European" HDV-1 and one HDV-6. This study shows that Nigeria is a country of low HDV prevalence where mainly "African" genotype-1 strains are circulating.