Hepatitis C virus quasispecies populations during chronic hepatitis C infection

Hepatitis C virus populations in infected individuals consist of quasispecies with diverse mutations. These quasispecies have different biological properties, and the analysis of these variants has led to new interpretations of viral persistence, carcinogenesis and resistance to interferon therapy.

Clinical relevance of hepatitis C virus quasispecies

It has been shown that hepatitis C virus (HCV) populations in infected individuals are composed of quasispecies with diverse mutations. The analysis of these variants may reveal mechanisms of the persistence of HCV infection, carcinogenesis and resistance to antiviral therapy. Recently, genetic features of interferon-resistant HCV have been elucidated through the analysis of interferon-resistant quasispecies, making it possible to predict interferon efficacy by detecting interferon-resistant strains.

Severe chronic active hepatitis induced by UFTR containing tegafur and uracil

A 77-year-old female patients developed severe hepatic injury after the administration of UFTR, which contains tegafur and uracil, for postoperative chemotherapy of colon cancer. Liver damage was recognized 10 months after its administration. Serum markers for viral hepatitis and various autoantibodies were negative. The wedged biopsied liver specimen revealed advanced chronic active hepatitis with periportal confluent necrosis, marked intralobular spotty necrosis, and significant proliferation of pseudo-bile ductules. Although the cessation of the drug and conservative therapies improved hepatic function, an accidental readministration of UFTR caused her severe hepatic damage again. These findings suggest that liver injury in the present case was caused by UFTR. Histological findings were unique. Although tegafur is known to worsen hepatic function when given to patients with liver cirrhosis, UFTR may also cause severe hepatic injury in those without preexisting liver disease.

Systemic hypotension and diuresis by L-arginine in cirrhotic patients with ascites: role of nitric oxide

To investigate the role of nitric oxide in renal function and hemodynamics in cirrhotic patients with ascites, L-arginine (30 g in 300 mL of distilled water), a substrate for nitric oxide synthase, was infused into six cirrhotic patients with ascites, and the effects were compared with those of saline infusion. Healthy controls (n = 5) were also studied under the same conditions. In the patients, L-arginine infusion significantly decreased systolic and diastolic blood pressures while markedly increasing urinary flow and urinary sodium excretion; no significant changes were seen with saline infusion. In controls, only diastolic blood pressure was decreased by L-arginine infusion, whereas urinary flow and urinary sodium excretion were increased by both L-arginine and saline infusion. In both groups, a similar increase of plasma atrial natriuretic factor (ANF) was seen with L-arginine and saline infusions; endothelin and catecholamines were not affected by either infusion. In both groups, plasma levels of vasopressin were increased by L-arginine infusion. In the cirrhotic patients, urinary excretions of cyclic guanosine monophosphate (cGMP) and nitrates/nitrites (NOx) were significantly increased by L-arginine infusion, whereas no significant changes were seen with saline infusion. In controls, only the excretion of cGMP was increased by L-arginine infusion. In summary, L-arginine infusion induces diuresis and natriuresis accompanied by increased excretions of cGMP and NOx in cirrhotic patients with ascites. This differs from the response in controls, where the increase in urinary sodium excretion is not accompanied by an increase in markers of increased nitric oxide synthesis.

Effects of cadmium on glutathione metabolism in Hep G2 cells

Effects of cadmium on hepatic glutathione (GSH) metabolism were characterized in a human-derived hepatoma cell line, Hep G2 cells. Intracellular GSH concentrations were significantly increased after incubation with cadmium at 5 and 10 microM for 24 and 48 hr. The rate of resynthesis of GSH after depleting cellular GSH by 0.5 mM of diethylmaleate was higher in cadmium (5 microM)-pretreated cells than that in untreated controls. GSH efflux from cadmium-pretreated cells was two-fold higher than that in untreated controls. On the other hand, incubation with cadmium at 5 and 10 microM for 60 min did not decrease GSH efflux. These findings suggest that increased intracellular GSH concentrations are attributed to enhanced synthesis of GSH under cadmium exposure, although the possibility of decreased intracellular consumption of GSH should further to be studied.

Ultraviolet B irradiation increases endothelin-1 and endothelin receptor expression in cultured human keratinocytes

The effect of ultraviolet B (UVB) irradiation on endothelin-1 (ET-1) and ET receptor expression was examined using cultured normal human keratinocytes. Keratinocytes secreted ET-1 in the medium at a level of 2.1 pg/day/10(5) cells. UVB irradiation up to 10 mJ/cm2 increased ET-1 secretion 3-fold, and potentiated expression of mRNA for ET-1. Both ETA and ETB receptor mRNAs were detected in keratinocytes, and their expression was up-regulated by 5 mJ/cm2 UVB irradiation.

Non-radioactive DNA diagnosis for the fragile X syndrome in mentally retarded Japanese males

A rapid screening test was developed to detect CGG repeat expansion of the FMR-1 gene causing the fragile X syndrome by a non-radioisotope PCR technique. A biotin-labeled primer was initially used and the biotin-labeled PCR product was detected by means of chemiluminescence. The normal PCR product of around 300 bp was not created in the abnormal FMR-1 gene sample with this method. Four positive samples were found among those from 226 mentally retarded males, but the CGG repeat expansion was shown on Southern blot analysis in only one sample. To eliminate false-positive samples, a hybridization method involving a biotin-labeled (CGG)s oligonucleotide was developed for the PCR product and the CGG repeat expansion could be detected. Finally, 256 mentally retarded males in Japan were examined and only 2 abnormal samples were detected. The prevalence of this abnormality was less than 1%, which is relatively lower than those reported previously.

Sodium channel functioning based on an octagonal structure model

The complete amino acid sequence of a sodium channel from squid Loligo bleekeri has been deduced by cloning and sequence analysis of the complementary DNA. A unique feature of the squid sodium channel is the 1,522 residue sequence, approximately three-fourths of those of the rat sodium channels I, II and III. On the basis of the sequence, and in comparison with those of vertebrate sodium channels, we have proposed a tertiary structure model of the sodium channel where the transmembrane segments are octagonally aligned and the four linkers of S5-6 between segments S5 and S6 play a crucial role in the activation gate, voltage sensor and ion selective pore, which can slide, depending on membrane potentials, along inner walls consisting of alternating segments S2 and S4. The proposed octagonal structure model is contrasted with that of Noda et al. (Nature 320; 188-192, 1986). The octagonal structure model can explain the gating of activation and inactivation, and ion selectivity, as well as the action mechanism of both tetrodotoxin (TTX) and alpha-scorpion toxin (ScTX), and can be applied not only to the sodium channel, but also to the calcium channel, potassium channel and cGMP-gated channel.

Encephalitozoon-like organisms in patients with alveolar hydatid disease: cell culture, ultrastructure, histoimmunochemical localization and seroprevalence

We found Encephalitozoon-like organisms in an in vitro culture of a human liver lesion which was due to larval Echinococcus multilocularis. The organisms developed in the same fashion as an Encephalitozoon cuniculi. The spores that developed in parasitophorous vacuoles were 2.0-2.6 x 1.1-1.5 microns; each contained a single nucleus and 4-5 polar tubule coils, closely resembling E. cuniculi in its ultrastructure. Mature spores were collected from the supernatants by the use of Percoll centrifugation resulting in the banding of the spores on continuous gradients. We prepared three sorts of spores which were different in buoyant density in 0.15 M NaCl: 1.05-1.07 g/ml spores, 1.12 g/ml spores, and spores of over 1.14 g/ml. Polyclonal antibodies to a pool of each spore preparation were produced in a rabbit and applied to the detection of microsporidian antigen in situ. The histoimmunoperoxidase (HIP) procedure was used to detect the microsporidian antigen in echinococcal liver lesions from patients with alveolar hydatid disease (AHD). Ten echinococcal liver lesions from different AHD patients were examined and four were found to be positive in the HIP test. The Percoll-separated spores were also used as an antigen to detect for antibodies in the sera from the patients with AHD by Western blotting. Antibodies were detected in 62 (52%) of the 119 AHD patients and in only 8 (5%) of the 159 normal healthy individuals.

Primers designed for amplification of Echinococcus multilocularis DNA amplify the DNA of Encephalitozoon-like spores in the polymerase chain reaction

Microsporidian spores were developed from cells which were grown in vitro from a human liver lesion which was due to larval Echinococcus multilocularis. The microsporidian spores developed in the same fashion as an Encephalitozoon cuniculi. The Encephalitozoon-like spores were completely separated on Percoll gradients. The separated spores contained DNA capable of amplification by two different primer sets designed for the polymerase chain reaction (PCR) of E. multilocularis DNA. However, the cell DNA from which microsporidium developed was thoroughly insensitive to the PCR using the E. multilocularis primer sets. The results strongly suggested that Encephalitozoon should be taken into consideration, when DNA isolated from larval E. multilocularis is analyzed.

Possible neuronal origin of ATP release evoked by forskolin and ouabain from guinea-pig atrial segments

The characteristics of ATP release evoked by forskolin and ouabain from atrial segments of guinea-pig were evaluated under electrical stimulation. Forskolin (1 microM) produced a massive release of ATP together with a positive inotropic response. Both 30 microM W-7 (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide.HCI), a calmodulin antagonist, and 30 microM vinblastine, a mitotic inhibitor, markedly inhibited the evoked release of ATP without affecting the evoked contraction. However, 100 microM N-ethylmaleimide abolished completely the basal and drug-evoked ATP release and further the evoked contraction. Both the ATP release and contraction evoked by ouabain (3 microM) were similarly affected by W-7, vinblastine and n-ethylmaleimide. The release of ATP, but not the contraction, evoked by forskolin was strongly suppressed by 10 microM okadaic acid, a protein phosphatase inhibitor. The suppression by okadaic acid of the evoked release was thoroughly antagonized in the presence of 0.01 microM PMA (phorbol 12-myristate 13-acetate), but not 10 microM H-7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine). These results suggest that forskolin, like ouabain, may dominantly cause the neuronal release of ATP from cardiac adrenergic nerves, although the possible participation of release from muscular sources cannot be ignored.

Characterization of the antigenic specificity of four different anti-(alpha 2-->8-linked polysialic acid) antibodies using lipid-conjugated oligo/polysialic acids

A rapid, sensitive, and facile method for screening and characterizing anti-polysialic acid (polySia) antibodies using lipid-conjugated oligo/polysialic acids (oligo/polySia) was developed, which is based on an enzyme-linked immunosorbent assay. Homooligo/polymers of alpha 2-->8-linked N-acetylneuraminic acid (Neu5Ac), N-glycoly-neuraminic acid, and 2-keto-3-deoxy-D-galacto-nononic acid (KDN) were conjugated with phosphatidylethanolamine dipalmitoyl (PE) by reductive amination to prepare neo-oligo/polysialoglycolipids (oligo/polySia-PE). Using this method, the anti-polySia equine antibody, H.46, bound to (-->8Neu5Ac alpha 2-->)n-PE, where n = 9 or more residues, a result in confirmation of previous binding studies using radiolabeled oligo/polyNeu5Ac. The antigenic specificity and sensitivity of two monoclonal anti-poly/oligoNeu5Ac antibodies (mAb.12E3 and mAb.5A5) and one anti-oligoKDN antibody (mAb.kdn8kdn), were also determined. mAb.12E3 could detect as little as 25 pg/well of oligo/polyNeu5Ac-PE, while 0.4 ng/well of oligo/polyNeu5Ac-PE to be detected. mAb.kdn8kdn detected as little as 12 ng/well of oligoKDN-PE. Using a series of oligo/polySia-PE with defined degrees of polymerization (DP), the minimum chain length for immunoreactivity of the anti-polySia antibodies was determined to be: DP 5 for mAb.12E3; DP 3 for mAb.5A5; DP 2 for mAb.kdn8kdn; and DP 8 for H.46. Thus, mAb.12E3 and mAb.5A5 recognize shorter oligomers of Neu5Ac than H.46, a finding that is of practical value for identifying shorter oligoSia chains in glycoconjugates. Because mAb.12E3 and mAb.5A5 also recognize extended polySia chains, these antibodies cannot be used, however, to differentiate between short and long chains of polySia when both are expressed on the same molecule.

Fraction-specific populations of the hypervariable region of the hepatitis C virus in a patient with cryoglobulinemia

Nucleotide sequences of the hypervariable region (HVR) of the E2/NS1 gene of hepatitis C virus (HCV), which are now thought to contain epitopes for neutralizing antibodies, were compared between antibody-bound HCV and free HCV in a patient with type II cryoglobulinemia. Antibody-bound HCV was immunoprecipitated with anti-human immunoglobulins from serum of the patient. Total RNA was recovered from the pellet and the supernatant, respectively, and the envelope gene containing the HVR was amplified by the reverse transcription and nested polymerase chain reaction. The amplified cDNA was examined by the single strand conformation polymorphism (SSCP) analysis. Sequences of bands separated by SSCP analysis were determined by the dideoxy chain termination method. SSCP analyses revealed that the HCV populations were completely different between antibody-bound HCV and free HCV: antibody-bound HCV was composed of two bands and free HCV was composed of three bands. These five bands showed different mobility with each other on the SSCP gel. Sequencing of each band revealed distinct HVR sequences, differing in 1-34 nucleotides and 1-15 deduced amino acids. Three sequences of free HCV was similar with each other (1-5 nucleotide and 1-4 amino acid differences). On the other hand, two sequences of antibody-bound HCV had 5-34 nucleotide and 5-15 amino acid differences with free HCV. Thirteen amino acids in the 5' of HVR were completely identical in three sequences of free HCV, whereas there were three and seven amino acid differences in two sequences of antibody-bound HCV. These findings suggest that isolated specific epitopes for envelope antibodies exist within the HVR.(ABSTRACT TRUNCATED AT 250 WORDS)

Patients with hepatitis A with negative IgM-HA antibody at early stages

Two patients with acute liver dysfunction who were negative for serum IgM-HA antibody on presentation became positive a week later. At early stages of hepatitis A, serum IgM-HA antibody may be negative. Another assay approximately 2 wk apart is recommended.

Limited usage of T-cell receptor beta chains and sequences of the complementarity determining region 3 of lymphocytes infiltrating in the liver of autoimmune hepatitis

To study the role of antigen-specific T lymphocytes in the pathogenesis of autoimmune hepatitis, messenger RNA of T-cell receptors (TCR) was analyzed in liver biopsy specimens from four patients with autoimmune hepatitis. Using the TCR beta-chain variable region family specific oligonucleotides, a remarkable bias for the usage of beta-chain variable region 3 was detected in all four patients. Therefore, nucleotide and amino acid sequences of the complementarity-determining region 3 rearranged to the beta-chain variable region 3, which is a putative contact site for peptide fragments from antigens bound in the groove of the human leukocyte antigen molecule, was further analyzed in randomly selected 10 clones from each patient. An Asp-Arg-Pro motif in the complementarity-determining region 3 was identified in three of four patients with human leukocyte antigen DR4, and this motif was always rearranged to the beta-chain junctional region 1.2. From these results, beta-chain variable region 3+, Asp-Arg-Pro+, beta-chain junctional region 1.2+ T-cell clones may be among the responsible lymphocytes involved in the liver damage in autoimmune hepatitis, especially in patients with human leukocyte antigen DR4. Thus, an analysis of the complementarity-determining region 3 may give us an important clue to clarify characteristics of target antigens included in autoimmune hepatitis.

Comparison of full-length sequences of interferon-sensitive and resistant hepatitis C virus 1b. Sensitivity to interferon is conferred by amino acid substitutions in the NS5A region

We have previously demonstrated that sensitivity to interferon is different among hepatitis C virus (HCV) quasispecies simultaneously detected in same individuals and that interferon-resistant HCV quasispecies are selected during the treatment. To determine the genetic basis of their resistance to interferon, HCV genotype-1b was obtained from serum of three patients before and during interferon therapy, and their full-length nucleotide and deduced amino acid sequences were determined. Comparison of the pairs of interferon-resistant and interferon-sensitive HCV isolates in respective individuals demonstrated clusters of amino acid differences in the COOH-terminal half of the NS5A region (codon 2154-2383), which contained a common unique amino acid difference at codon 2218. Additional sequence data of the COOH-terminal half of the NS5A region obtained from six interferon-resistant and nine interferon-sensitive HCV confirmed the exclusive existence of missense mutations in a 40 amino acid stretch of the NS5A region around codon 2218 (from codon 2209 to 2248) in interferon-sensitive HCV. On the other hand, this region of interferon-resistant HCV was identical to that of prototype HCV genotype-1b (HCV-J, HCV-JTa, or HC-J4). We designated this region as the interferon sensitivity determining region. Thus, HCV genotype-1b with the prototype interferon sensitivity determining region appears to be interferon-resistant strains. The specific nature of these mutations might make it possible to predict prognostic effects of interferon treatment.

Diversity of quasispecies in various disease stages of chronic hepatitis C virus infection and its significance in interferon treatment

Hepatitis C virus (HCV) populations in vivo exist as a mixture of heterogeneous viruses called quasispecies, which have variations in the hypervariable region (HRV). However, the relationship between the diversity of HVR quasispecies, the disease stage, or the interferon (IFN) responsiveness remains to be elucidated. To study these, serum samples were obtained from 42 patients with chronic hepatitis C virus infection; 24 with chronic active hepatitis (CAH) treated with IFN, 9 with cirrhosis, 9 with hepatocellular carcinoma (HCC). HCV quasispecies populations were separated by the single-strand conformation polymorphism (SSCP) method targeted to the HVR. The patients were classified into two groups; a single-band group (n = 12) in which HVR quasispecies was homogeneous and a multiple-band group (n = 30) in which HVR quasispecies was heterogeneous. Patients with multiple bands had significantly more advanced liver disease than those with a single-band group (P = .0082). The percentage of patients with single band were 41% in CAH, 22% in cirrhosis, and 0% in HCC. Multivariate analyses showed that viral diversity was independently related to the progression of liver disease and was not correlated with the duration of infection. We also found that in CAH, the patients who had multiple bands (n = 14) were more resistant to IFN therapy than those who had a single band (n = 10) (P = .002). These results indicate that the diversity of HCV quasispecies becomes more complex as the disease stage progresses and that CAH with more complex diversity shows less IFN effectiveness.

Prediction of relapses after interferon-alpha therapy by hepatitis C virus RNA in peripheral blood mononuclear cells

To investigate the predictive value of hepatitis C virus (HCV)-RNA in peripheral blood mononuclear cells in the response to interferon therapy in patients with chronic hepatitis C, 15 patients with histologically proven chronic active hepatitis and who were positive for serum HCV-RNA were treated with interferon-alpha (6 million units; i.m.) every day for two weeks and then three times a week for 22 weeks. Ten of the 15 patients were responders whose alanine aminotransferase levels decreased to the normal range at the end of interferon therapy. In four of the 10 responders, HCV-RNA was not detected by reverse transcription-polymerase chain reaction in peripheral blood mononuclear cells nor in serum at the end of treatment. These four patients were complete responders, with alanine aminotransferase levels remaining normal for the next 24 weeks. In five of the 10 responders, HCV-RNA was detected in peripheral blood mononuclear cells but not in serum at the end of treatment. All of these relapsed within the next 24 weeks. In the remaining responder, HCV-RNA was detected both in peripheral blood mononuclear cells and in serum at the end of treatment. This responder also had a relapse within the next 24 weeks. Five of the 15 patients were non-responders, in whom HCV-RNA was detected both in peripheral blood mononuclear cells and in serum. Thus, detection of HCV-RNA in peripheral blood mononuclear cells may be a good clinical marker to predict relapse after interferon treatment.

Comparative study of hepatocyte growth factor/scatter factor and keratinocyte growth factor effects on human keratinocytes

Hepatocyte growth factor/scatter factor (HGF/SF) and keratinocyte growth factor (KGF, also designated FGF-7) are paracrine growth factors secreted by mesenchymal cells and active on a variety of epithelial cell types. In this study, the biologic responses of keratinocytes to these paracrine growth factors were compared. Stimulation of mitogenesis, migration, plasminogen activator (PA) activity, and fibronectin production were examined using human foreskin keratinocytes cultured in serum-free MCDB 153 medium. Although the two factors stimulated a similar level of proliferation when cells were maintained for 5 d in 1.8 mM Ca++, the peak effect of KGF, observed at 10 ng/ml, was approximately threefold higher than that of HGF/SF when cells were in medium containing 0.15 mM Ca++. Both agents promoted the migration of cells in low-calcium medium (0.08 mM Ca++). However, the magnitude of the response was approximately twofold greater for HGF/SF at 10 ng/ml than KGF at the same concentration. None of the matrix proteins such as type I collagen, type IV collagen, laminin, or fibronectin either stimulated or suppressed HGF/SF- or KGF-stimulated keratinocyte migration. Both factors stimulated PA activity of the cell extracts, especially urokinase-type, with similar potencies. Promoted PA activity was maximal with the addition of 10 ng/ml of either factor. Neither factor increased the production of fibronectin under conditions in which transforming growth factor-beta 1 was active. These results indicate that HGF/SF and KGF, both recognized as paracrine growth factors, elicit distinctive patterns of response by keratinocytes, implying that they have different roles in epidermal physiology.

Human alveolar echinococcosis seroprevalence assessed by western blotting in Hokkaido

To investigate the recent prevalence of human alveolar echinococcosis in Hokkaido, we took advantage of Western blotting analysis capable of classifying persons infected with Echinococcus multilocularis into two groups: the complete and incomplete types. From the geographic distribution, the residents with the complete type appeared for the first time in 1992 in the Oshima district (western Hokkaido). The age distribution indicated that persons with the complete type increased, since 1990, in the age groups younger than 30 years old.

Variations in the core region of hepatitis C virus genomes in patients with chronic hepatitis

In each infected patient, the population of hepatitis C virus is composed of quasispecies that differ in their nucleotide sequences. Among regions in hepatitis C virus genomes, nucleotide sequences of the hypervariable region have been shown to change quickly during the course of infection. It is not known, however, whether these variations exist in the core region that has recently been suggested to contain human lymphocyte antigen class 1 restricted sites for cytotoxic T cell recognition. To clarify this, RNA was extracted from the plasma of four patients with chronic hepatitis C. After cDNA synthesis, DNA fragments that contain the core region were amplified by the polymerase chain reaction and the diversity of the core region was analyzed by the single strand conformation polymorphism analysis. Using this method, single or multiple DNA bands were observed in each patient, and representative bands showed different nucleotide sequences. Comparison of single strand conformation polymorphism patterns revealed that the population of quasispecies changed during the course of chronic infection. These changes were more remarkable in patients with high serum alanine aminotransferase levels than those with low serum alanine aminotransferase levels. Thus, sequential variations exist in the core region of hepatitis C virus in same individuals, and the population of quasispecies as determined by the sequence of the core region changes during the course of infection, which might be related to cytopathic effects of hepatitis C virus.