Hepatitis E virus infection and acute-on-chronic liver failure in West Africa: a case-control study from The Gambia.

BACKGROUND: In sub-Saharan Africa, it is unknown whether hepatitis E virus (HEV) infection is a common precipitating event of acute-on-chronic liver failure (ACLF). AIMS: To estimate the prevalence of HEV infection in general population and assess whether HEV is a common trigger of ACLF in cirrhotic patients in The Gambia, West Africa. METHODS: We first conducted an HEV sero-survey in healthy volunteers. We then tested cirrhotic patients with ACLF (cases) and compensated cirrhosis (controls) for anti-HEV IgG as a marker of exposure to HEV, and anti-HEV IgA and HEV RNA as a marker of recent infection. We also described the characteristics and survival of the ACLF cases and controls. RESULTS: In the healthy volunteers (n = 204), 13.7% (95% CI: 9.6-19.2) were positive for anti-HEV IgG, and none had positive HEV viraemia. After adjusting for age and sex, the following were associated with positive anti-HEV IgG: being a Christian, a farmer, drinking water from wells, handling pigs and eating pork. In 40 cases (median age: 45 years, 72.5% male) and 71 controls (39 years, 74.6% male), ≥70% were infected with hepatitis B virus. Although hepatitis B flare and sepsis were important precipitating events of ACLF, none had marker of acute HEV. ACLF cases had high (70.0%) 28-day mortality. CONCLUSIONS: Hepatitis E virus infection is endemic in The Gambia, where both faecal-oral route (contaminated water) and zoonotic transmission (pigs/pork meat) may be important. However, acute HEV was not a common cause of acute-on-chronic liver failure in The Gambia.

An autoantibody cross-reactive to hepatitis C virus core and a host nuclear antigen.

GOR, an epitope borne by the amino acid sequence, GRRGQKAKSNPNRPL, is recognized by anti-GOR antibodies specifically found in patients with non-A, non-B hepatitis (NANBH). The epitope is not coded for by the hepatitis C virus (HCV), the presumed causative agent for NANBH, but by a single copy gene of the host. Anti-GOR antibodies, distinct from anti-HCV (c100-3) antibodies, were revealed to have dual specificities; they target both the presumed core gene product of HCV and a host component. This cross recognition is probably derived from homologous regions between the GOR epitope and a viral epitope on the core protein in HCV. It is therefore suggested that anti-GOR is an autoantibody induced by HCV infection. This may explain the autoimmune disease like aspect of NANBH pathogenesis.

Transmission of hepatitis C virus from mothers to infants: its frequency and risk factors revisited.

A total of 16,714 pregnant Japanese women were tested for antibodies against hepatitis C virus (HCV), and 163 (0.98%) were positive. None of these were infected with human immunodeficiency virus-1 (HIV-1). We conducted a prospective study to discover the rate of HCV infection in babies born to mothers who were HCV RNA-positive but had no evidence for hepatitis (so called "asymptomatic carriers"), and only 2 (2.3%) of 87 such babies became infected during follow-up. This rate was considerably lower than those from other reports which included mothers with clinically overt chronic hepatitis C. We conducted another study to follow babies born to mothers with chronic hepatitis C, and found two babies infected. All of the four infected babies were born to mothers who had HCV RNA in their circulations around delivery at high titers (greater than 5.0 x 10(6) Eq/ml by branched DNA assay). This confirmed the previous finding that virus load was an important risk factor. In addition, we found three families where mother-to-infant HCV transmission was suspected in a retrospective study by indexing HCV-infected pediatric patients. Throughout the seven families, siblings of infected babies were free from HCV infection, suggesting that maternal infection of HCV owes much to chance. Breast milk feeding was not regarded as a risk factor. We also assessed the prevalence of anti-HCV antibody among 6-year old children, and only 10 of 10,446 (0.1%) were positive, suggesting low frequency of HCV infection during the period from birth to this age.

Hepatitis C virus (HCV) genotype 1b sequences from fifteen patients with hepatocellular carcinoma: the 'progression score' revisited.

The genome of hepatitis C virus (HCV) associated with hepatocellular carcinoma (HCC) may have some characteristics which would barely be found in those of HCV from asymptomatic carriers (ASC). We analyzed 15 HCC patients who were infected with HCV genotype 1b (HCV-1b) for complete nucleotide sequences of the viral genomes. Of the 15 isolates, three were sequenced up to the first nucleotide of the 5'UTR, and six were sequenced to encompass the X-tail at the 3' end: sequencing of at least three-quarters of the 5'UTR and entire polyprotein-ORF was accomplished in all 15 isolates. Analyses of these sequences together with those reported previously by Nagayama et al. [Hepatology; 31 (2000) 745] suggested that nine residues (nt 119 of 5'UTR and aa 90, 434, 938, 962, 1176, 1412, 2143, and 2774 of polyprotein) might be useful to discriminate HCC-type sequences from ASC-type ones. The 'progression score' was 1.4+/-0.9 in ASC versus 3.7+/-1.5 in HCC (P=3.87E-07) when calculated with the Nagayama et al.'s seven residues, but was 1.4+/-0.6 versus 4.6+/-1.9 (P=1.33E-09) with our nine residues: a greater difference between HCC and ASC was achieved in the latter system. Further analyses, by increasing the sample size and/or by extending the comparison to include entire 5'UTR and 3'UTR/X-tail, may thus contribute to define the 'progression score' more appropriately.

[Prevalence of genotypes of the hepatitis C virus, circulating in northwestern and central parts of Russia]. / Rasprostranenie genotipov virusa gepatita C, tsirkuliruiushchikh na territoriiakh severo-zapadno i i tsentral;no i chaste i Rossii.

Testing of 90 sera for antibodies to hepatitis C virus (HCV) by genotyping methods resulted in determination of the genotype in 83 cases: 47 cases with 1b genotype, 27 with 1a, 7 with 3a, 1 with 2a, and 1 with 2b genotype. Hence, preliminary data indicate the predominance of HCV genotype 1b among patients with hepatitis C in these regions of Russia.

[Regularities in the spread of hepatitis C virus and its genotypes in Russian and countries within the former USSR]. / Zakonomernosti rasprostraneniia virusa gepatita C i ego genotipov v Rossii i stranakh SNG.

The incidence of markers of hepatitis C virus (HCV in the blood of 4216 normal subjects living in the European Russia (Northern, North-Western, Central, Central Chernozem, Volga-Vyatka, Volga, and North Caucasian regions), in the Urals, in Siberia (Eastern Siberian region), in the Far East, and in Monogolia is assessed. The incidence of antibodies to HCV varied from 0.7% in the Central region to 3.8% in the Central Chernozem and 10.7% in Mongolia. HCV genotyping (identification of 1a, 1b, 2a, 2b, and 3a genotypes) was performed using 469 RNA of HCV-positive sera of donors and patients collected in Russia, Moldova, Turkmenistan, and Mongolia. The 1b genotype predominated everywhere (68.9%), its incidence being the highest in Moldova (96%). Unclassifiable variants of HCV were found in 28 (6%) of sera. The regularities of HCV genotypes circulation in the European Russia were the same as in other European countries, whereas their prevalence in Eastern Russia was rather like that in China or Japan. The prevalence of genotypes did not depend on the clinical manifestations of diseases caused by HCV.

Genetic heterogeneity of hepatitis C virus.

There are four hierarchical strata in the genetic heterogeneity of hepatitis C virus (HCV): group above subgroup above isolates above quasispecies. The entire genome sequence has so far been reported for 16 isolates which are classifiable into 3 groups and 6 subgroups. Provisional classification of HCV is also possible using a partial sequence of the HCV genome. With the E1 region sequence for example, the present collection of HCV isolates can be classified into 9 groups and 23 subgroups. The rationale for these classifications and the epidemiological and clinical implications of genotyping HCV are reviewed.

Identification of a single nucleotide polymorphism in the MxA gene promoter (G/T at nt -88) correlated with the response of hepatitis C patients to interferon.

The interferon (IFN)-inducible MxA protein is known to play an important role in the host defense against certain viruses. We aimed to see if any genetic polymorphism in the promoter region of the MxA gene is associated with the IFN responsiveness of hepatitis C virus (HCV)-infected patients. Initially we sequenced the promoter region of the MxA gene in 12 subjects and found a polymorphic site. We then constructed a specific PCR-RFLP system for this site and subjected 63 samples from chronic hepatitis C patients who were nonresponders (NR) to IFN therapy to it, 52 with sustained response (SR), and 42 healthy controls. Subjects were all Japanese, and unrelated. A single nucleotide polymorphism (SNP) was identified in the MxA promoter region: G/T alleles at nt position -88. Interestingly, this SNP was involved in a genetic element highly homologous to the IFN-stimulated response element consensus sequence, and the G-to-T change there makes this homology a little greater. The rate of G.G homozygosity was 31% in the SR patients, significantly lower than in the NR patients (62%, p = 0.0009), while that of healthy controls was between the two groups (48%). Differences in HCV genotypes did not influence this result. Based on these findings, we propose that the SNP of the MxA promoter at nt -88 identified in this study affects the expression of MxA protein, and may thus be associated with the response of HCV patients to IFN.

Detection of the GBV-C hepatitis virus genome in serum from patients with fulminant hepatitis of unknown aetiology.

Hepatitis viruses A, B, C, D, and E have not accounted for all cases of hepatitis, hence "non A-E" agent(s) might be implicated. A set of new viruses (GBV-A, -B, and -C) whose genomes have been sequenced, are being investigated as possible causes of non A-E hepatitis. We investigated six cases of fulminant hepatitis of unknown aetiology for the presence of GBV-C genome in their serum, and three showed positive signals by semi-nested PCR using primers derived from the NS3/helicase region. Nucleotide sequence analyses confirmed these signals to be derived from a GBV-C sequence. The results suggest the importance of GBV-C in the aetiology of fulminant hepatitis.

Complete circular DNA genome of a TT virus variant (isolate name SANBAN) and 44 partial ORF2 sequences implicating a great degree of diversity beyond genotypes.

Information on the entire genome of TT virus (TTV) has been scarce. The circular ssDNA genome of a variant (isolate name SANBAN) that we sequenced was only 56.7% homologous to the prototype isolate (TA278), with even lower homology at the amino acid level: 34.2% for ORF1 and 39.7% for ORF2. Regarding the ORF1, SANBAN was only very distantly related to the six major TTV genotypes reported to date. In partial ORF2 sequences determined on 44 isolates taken together, TTV has a broad range of genetic diversity and the SANBAN isolate may represent a new TTV-like viral species or genus and not merely a genotype of TTV.

Identification of a new human DNA virus (TTV-like mini virus, TLMV) intermediately related to TT virus and chicken anemia virus.

TT virus (TTV) is the only known human virus with single-stranded circular DNA, with a possible but yet unclear relationship to chicken anemia virus (CAV) of the family Circoviridae. Here we report a new human virus resembling TTV and CAV, designated TTV-like mini virus (TLMV). This non-enveloped virus was smaller (< 30 nm) but had a similar density (1.31-1.34 g/ml in CsCl) to TTV, when a TLMV/TTV-coinfected plasma was analyzed. Full-length sequencing revealed that the TLMV genome was a circular DNA comprising 2860 nt (isolate CBD231); significantly shorter than TTV (TA278, 3852 nt) but longer than CAV (CAECUX1, 2319 nt). A strand-specific hybridization assay using oligonucleotide-coated beads suggested TLMV was negative-stranded, like TTV and CAV. In genomic organization, TLMV was similar to both TTV and CAV. The untranslated region of TLMV resembled CAV in that both had direct repeats, whereas the sequence homology was more evident between TLMV and TTV. The predicted ORF1 protein of TLMV was rich in R/W/F residues at its amino terminus; the richness in W was shared by TTV, F by CAV, and R by both. ORF2 proteins of the three viruses had a common motif, WX7HX3CXCX5H. Thus, TLMV is an intermediate between the remotely related TTV and CAV. Since CAV differs much from other circoviruses, it may better be classified together with TTV and TLMV under a new family: we would coin the Paracircoviridae.

Full or near full length nucleotide sequences of TT virus variants (Types SANBAN and YONBAN) and the TT virus-like mini virus.

TT virus (TTV) is a common virus and consists of many genotypes and variants. In addition, there exists a virus which both differs greatly from and retains a considerable resemblance to TTV, such as the TTV-like mini virus (TLMV) as we reported previously. Here we report the near full length genomic sequences of 4 isolates of a new variant of TTV (designated YONBAN) along with the full length sequences of 2 isolates of the TTV-SANBAN lineage and 7 isolates of the TLMV species derived from human sera. The TTV-YONBAN sequences showed only about 50% identity at the nucleotide level to those of the prototype TTV (TA278) and to SANBAN, and even less to TLMV. Moreover, the ORF1 of YONBAN lacked the ATG initiation codon which is shared by all the TTV and TLMV isolates so far identified in humans; instead, YONBAN had a Kozak's rule-compatible ACG codon as the candidate initiation site for the ORF1 translation. Nevertheless, the overall genetic structure and the conserved amino acid motifs within the ORF1 and the ORF2 were well shared among the prototype TTV strains, the SANBAN and YONBAN variants, and TLMV. The most conserved nucleotide sequence was found in the noncoding region just upstream from the ORF2, allowing construction of a phylogenetic tree which implied that the TTV genotypes and variants, the TLMV, and chicken anemia virus could be coclassified under a superfamily for which we proposed the name of 'Paracircoviridae' in our previous report.