Serial transmission of spongiocytic hepatitis to woodchucks (possible association with a specific delta strain)

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.

In the Central African Republic (CAR), due to 20 years of conflict, the health system has been disorganized. This could contribute to maintenance of high transmission levels of Hepatitis B Virus (HBV) and its satellite Hepatitis Delta Virus (HDV). This work studies the evolution of both infections 25 years after a fulminant hepatitis (FH) outbreak occurring in the mid-1980s associated with HDV superinfection. In young asymptomatic adults, the results show that both HBV and HDV were still actively circulating in CAR in 2010. Indeed, more than one third of HBV-infected individuals were chronic HBV carriers. Furthermore, HDV infection could be spreading among 10% of them through blood and sexual transmission. The past FH outbreak and contemporary infections were both associated with heterogeneous HDV-1 strains, combined with HBV-E. Vaccination against HBV was uncommon among pregnant women and students, even among medical students. The study constitutes warning signals to help CAR health-care reconstruction and underlines the importance of HBV vaccination. The high level of HBV infection creates a background for HDV superinfection. Neonatal HBV vaccination is needed, together with vaccination of unprotected populations. Awareness of health authorities as well as the general public would help reduce HBV and HDV infections.

Epidemiology and diagnosis of hepatitis D virus

The distribution of hepatitis D virus (HDV) is worldwide but not uniform. Current estimates suggest that 15–20 million people have exposure to HDV. Traditionally, areas of high prevalence are the Mediterranean basin, the Middle East, central Africa, the Amazonian basin and parts of Asia. As a consequence of vaccination against HBV and other prophylactic measures, the prevalence of HDV declined in Italy, Spain, Turkey and Taiwan. This downward trend stopped in the 1990s; a new location for HDV epidemics arose in western Europe, due to migration from endemic areas. HDV appeared in new geographic regions, posing a serious health threat in underdeveloped countries. Testing for anti-HVD antibodies in serum is the initial step in diagnosing HDV infection, but unravelling HDV RNA is essential to identify active replication.

Clevudine inhibits hepatitis delta virus viremia: a pilot study of chronically infected woodchucks

In a small controlled study, clevudine, a potent inhibitor of hepadnaviruses, including hepatitis B virus and woodchuck hepatitis virus, suppressed hepatitis delta virus (HDV) viremia in chronically infected woodchucks. Suppression was correlated with the marked reduction of woodchuck hepatitis virus surface antigen in individual animals, consistent with the concept that repression of surface antigen expression may be a useful antiviral strategy for HDV.

Molecular phylogenetic analyses indicate a wide and ancient radiation of African hepatitis delta virus, suggesting a deltavirus genus of at least seven major clades

Hepatitis D virus (HDV) is a satellite of hepatitis B virus (HBV) for transmission and propagation and infects nearly 20 million people worldwide. The HDV genome is a compact circular single-stranded RNA genome with extensive intramolecular complementarity. Despite its different epidemiological and pathological patterns, the variability and geographical distribution of HDV are limited to three genotypes and two subtypes that have been characterized to date. Phylogenetic reconstructions based on the delta antigen gene and full-length genome sequence data show an extensive and probably ancient radiation of African lineages, suggesting that the genetic variability of HDV is much more complex than was previously thought, with evidence of additional clades. These results relate the geographic distribution of HDV more closely to the genetic variability of its helper HBV.

Schistosomiasis mansoni and viral B hepatitis in woodchucks

BACKGROUND/AIMS

An interaction between human schistosomiasis and viral hepatitis B has often been suggested, but never established. The experimental investigation has been hampered by the lack of a suitable model. Only woodchucks are susceptible to both Schistosoma mansoni and a B-like hepatitis virus (WHV) infections. This study explores the relevance of this unique model regarding hepatitis/schistosomiasis interactions.

METHODS

Woodchucks (Marmota monax and Marmota marmota) were infected with: (a), S. mansoni; (b), WHV; or (c), both S. mansoni and WHV.

RESULTS

Following the experimental parasitic infection of woodchucks, with or without WHV, schistosomiasis presented a peculiar and severe course in early infection, involving mostly the intestines. Subsequently, the intestinal and hepatic lesions underwent considerable modulation and the periovular granulomas decreased in size and number, while the parasitic infection tended to self-cure within the 9 months following infection. Nine woodchucks inoculated with the hepatitis virus alone presented with several degrees of acute and chronic hepatitis, with one of them dying of hepatocarcinoma 1 year after inoculation. Four woodchucks with concomitant viral and schistosome infections presented with a simple additive pattern of lesions, without any evidence of modification or aggravation of either one of the two infections. Similarly, no significant impact of schistosomiasis on WHV serum markers could be seen.

CONCLUSIONS

Schistosomiasis and viral hepatitis in woodchucks run parallel courses, with neither apparent special histological features derived from the association of the two conditions, nor modulation of WHV replication. Schistosomiasis itself, however, was observed to run a peculiar course in the woodchuck. The present data are important for consideration in further experiments exploring the interplay between schistosomiasis and viral hepatitis induced liver damage in this unique experimental host.

Analysis of a hepatitis delta virus isolate from the Central African Republic

Based on the analysis of HDV genomes from different areas of the world, three genotypes of HDV have been identified. Genotype I is the most prevalent and widespread. Genotype II is represented by two isolates from Japan and Taiwan. Genotype III has been found only in the Amazonian basin where it is associated with a history of severe disease, fulminant hepatitis with microvesicular steatosis (spongiocytosis). We report here the cloning and the analysis of the complete viral genome from woodchuck serum-derived HDV RNA after transmission from Central African Republic (RCA) patients with fulminant spongiocytic delta hepatitis. Two overlapping cDNA fragments, covering the entire HDV genome, were generated by RT-PCR and cloned. Three clones obtained from each fragment were fully sequenced. A complete consensus RCA HDV genome was reconstituted. The individual and the consensus nucleotide sequences were compared with those of 16 other fully sequenced isolates belonging to the three genotypes. Phylogenetic trees generated by the neighbour joining method firmly place our isolate in genotype I, and show that this RCA isolate differs significantly from the east African isolates previously analysed. Transfection experiments showed that the isolate is replication-competent, but less so than the control "wild-type" strain. Two novel mutations encountered in this work, one in the antigenomic ribozyme sequence and one affecting delta antigen, were studied.

Review: hepatitis delta

The causative agent of hepatitis delta virus (HDV) is the most unusual of all causative agents for all hepatitis viruses. Current knowledge of the molecular biology of HDV strengthens its proposed classification within the satellites, a family of subviral agents, some of which are pathogens of higher plants. Hepatitis delta virus is the only virus in the satellite family known to infect animal species, with hepatitis D having affected more than 10 million people worldwide who are also infected with its helper virus, HBV. Recently, the world map for hepatitis D appears somewhat modified, with decreasing HDV prevalence in certain areas and some new foci of HDV endemicity. Despite changing HDV prevalence, hepatitis. D, particularly the chronic form, is still an important health problem worldwide in terms of morbidity and mortality (mainly due to chronic liver disease, including hepatocellular carcinoma). Molecular studies have greatly advanced our understanding of the life cycle of HDV and of the function of its proteins. The new molecular information is of clinical relevance, with implications for the pathogenesis of liver damage, the diagnosis of HDV infection, for the natural course of the disease and, potentially, for therapy. Sensitive assays for HDV-RNA by polymerase chain reaction and sequencing techniques have clarified the patterns of HDV transmission and have confirmed the existence of unusual clinical forms of the virus and their relationship to replicative levels and genotypes of HDV. Prevention and treatment of hepatitis D are still in their infancy. However, liver transplantation for delta cirrhosis has proven far more successful than in any other viral form of cirrhosis, with few reinfections of the grafted liver, and has given important information on HDV biology and the pathogenesis of liver damage.

A new hepadnavirus endemic in arctic ground squirrels in Alaska

We present evidence for a novel member of the hepadnavirus family that is endemic in wild arctic ground squirrels (Spermophylus parryi kennicotti) in Alaska. This virus, designated arctic squirrel hepatitis virus (ASHV), was initially detected in the livers of animals bearing large hepatic nodules by nucleic acid hybridization with hepadnavirus probes and in plasma by cross-reactivity with antibodies to hepadnavirus surface and core antigens. The complete nucleotide sequence of the 3,302-bp-long ASHV genome was determined and compared with those of ground squirrel hepatitis virus (GSHV) and woodchuck hepatitis virus (WHV); all sequences were organized into four open reading frames, designated pre-C/C, pre-S/S, pol, and X. Despite roughly equivalent variability among the three rodent hepadnaviruses (around 16% base and 19% amino acid exchanges), ASHV appeared to be more closely related to GSHV than to WHV in phylogenetic analysis. Accordingly, preliminary studies of the pathology of ASHV infection suggested that ASHV may be a less efficient oncogenic agent than WHV. About one-third of aged animals maintained in captivity, including virus-infected as well as uninfected squirrels, developed large liver nodules, consisting of hepatocellular adenomas or carcinomas or nonmalignant lesions characterized by drastic microvesicular steatosis. ASHV-infected arctic ground squirrels may serve as a new model with which to analyze the contribution of hepadnavirus- and host-specific determinants to liver pathology and tumorigenesis.