Kazuhiko Hosoda

Mutations in the Precore Region of Hepatitis B Virus DNA in Patients with Fulminant and Severe Hepatitis

BACKGROUND The presence of the hepatitis B e antigen (HBeAg) in serum is known to be a marker of a high degree of viral infectivity. However, fulminant hepatitis may occur in persons who are negative for HBeAg. A single point mutation has been reported to produce a stop codon in the precore region of hepatitis B virus DNA and prevent the formation of the precore protein required to make HBeAg. To determine whether a precore-mutant virus is causally related to severe liver injury, we analyzed the entire precore region in viral strains isolated from patients with fatal cases and uncomplicated cases of hepatitis B. METHODS Serum was obtained from 9 patients with fatal hepatitis B (5 with fulminant and 4 with severe exacerbations of chronic hepatitis) and 10 patients with acute, self-limited hepatitis B. Serum samples from a sex partner implicated as the source of the virus in one case of fulminant hepatitis were also studied. The 87 nucleotides in the precore region of the hepatitis B virus were amplified by the polymerase chain reaction and then directly sequenced. RESULTS Of the nine patients with fatal hepatitis, seven had retrievable hepatitis B DNA: In all seven there was a point mutation from G to A at nucleotide 1896 of the precore region, converting tryptophan (TGG) to a stop codon (TAG). In contrast, this mutation was not found in the 10 patients with acute, self-limited hepatitis B. The hepatitis B DNA from the implicated source contained a sequence with the stop-codon mutation that was identical to the sequence in her partner, who had fulminant hepatitis. CONCLUSIONS The presence of a mutant viral strain is associated with and may be involved in the pathogenesis of fulminant hepatitis B and severe exacerbations of chronic hepatitis B.

Resolution of acute hepatitis C after therapy with natural beta interferon

To test whether interferon can prevent acute non-A, non-B hepatitis from becoming chronic, a prospective controlled trial was conducted in 25 patients; 11 were treated for an average of 30 days with a mean of 52 megaunits of interferon and 14 acted as controls. 4 patients in the treatment group who continued to have raised serum aminotransferase concentrations after a years follow-up were given a second course of interferon. Follow-up at 3 years has revealed that all but 1 of those treated showed normal serum aminotransferase, whereas only 3 controls showed such change (p less than 0.02). Serum hepatitis C virus RNA became undetectable in 10 of 11 treated and in only 1 of 12 control patients, which suggests that interferon prevents the progression of acute non-A, non-B hepatitis to chronicity by eradicating HCV.

Variations in codons 84-101 in the core nucleotide sequence correlate with hepatocellular injury in chronic hepatitis B virus infection.

Individuals with chronic hepatitis B virus (HBV) infection are generally divided into asymptomatic healthy carriers and patients with chronic liver disease. Several studies have suggested that the hepatitis B core antigen could be an immunological target of cytotoxic T lymphocytes (CTL). To investigate the possible pressure site from CTL, the entire core region of HBV DNA was sequenced in 30 subjects (10 asymptomatic healthy carriers and 20 patients with chronic liver disease). No significant changes in the nucleotide sequence and deduced amino acid residue were noted in the 10 healthy carriers. In contrast, a cluster of changes in a small segment of 18 amino acids (codons 84-101 from the start of the core gene) was found in 15 of the 20 chronic liver disease patients. All these 15 patients had advanced liver diseases (chronic active hepatitis and cirrhosis), whereas only mild liver disease (chronic persistent hepatitis) was found in the five patients without mutations. These data suggest that the region with mutation clustering is the major target of CTL, and that the mutations evolve under the pressure of immune selection.

Detection of hepatitis C virus ribonucleic acid in the serum by amplification with polymerase chain reaction.

Hepatitis C virus (HCV) RNA was detected in the sera of patients with non-A, non-B chronic liver disease by polymerase chain reaction (PCR). RNA was extracted from the serum, reverse transcribed to cDNA, and amplified by PCR. With this method, 30 patients with non-A, non-B chronic liver disease and 10 healthy subjects were tested. HCV RNA was detected in 13 of 16 (81%) anti-HCV-positive patients and also in 7 of 14 (50%) anti-HCV-negative patients, but in none of 10 anti-HCV-negative healthy subjects. Specificity of this method was confirmed by direct sequencing of amplified cDNA segment. The nucleotide sequences (37 nucleotides) obtained from 15 patients showed only 68-78% homology compared with the prototype HCV nucleotide sequence. In addition, of 15 nucleotide sequences, there were 12 different types. But the translated amino acid sequences (12 amino acids) showed 83-100% homology compared with the prototype HCV amino acid sequence. These data suggest the majority of anti-HCV-positive patients are carriers of HCV. But to detect all the viremic patients, the anti-HCV antibody testing may be insufficient. Direct detection of HCV RNA may be useful in the study of virus replication and its association with various liver diseases.

Mutations in core nucleotide sequence of hepatitis B virus correlate with fulminant and severe hepatitis.

Infection with hepatitis B virus leads to a wide spectrum of liver injury, including self-limited acute hepatitis, fulminant hepatitis, and chronic hepatitis with progression to cirrhosis or acute exacerbation to liver failure, as well as an asymptomatic chronic carrier state. Several studies have suggested that the hepatitis B core antigen could be an immunological target of cytotoxic T lymphocytes. To investigate the reason why the extreme immunological attack occurred in fulminant hepatitis and severe exacerbation patients, the entire precore and core region of hepatitis B virus DNA was sequenced in 24 subjects (5 fulminant, 10 severe fatal exacerbation, and 9 self-limited acute hepatitis patients). No significant change in the nucleotide sequence and deduced amino acid residue was noted in the nine self-limited acute hepatitis patients. In contrast, clustering changes in a small segment of 16 amino acids (codon 84-99 from the start of the core gene) in all seven adr subtype infected fulminant and severe exacerbation patients was found. A different segment with clustering substitutions (codon 48-60) was also found in seven of eight adw subtype infected fulminant and severe exacerbation patients. Of the 15 patients, 2 lacked precore stop mutation which was previously reported to be associated with fulminant hepatitis. These data suggest that these core regions with mutations may play an important role in the pathogenesis of hepatitis B viral disease, and such mutations are related to severe liver damage.

Histological changes of the liver by treatment of chronic non-A, non-B hepatitis with recombinant leukocyte interferon alpha

We have treated 17 patients with non-A, non-B chronic hepatitis by recombinant interferon alpha (0.3–9 megaunits for 4–28 weeks). In six patients, serum aminotransferase levels fell to normal or near-normal range during treatment. The mean levels of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in 17 patients fell from 156±80 (mean±sd) and 213±135 at the beginning of treatment to 94±49 and 112±71, respectively, at the end of treatment. In 12 patients, liver biopsies were performed before and after (or during) the treatment, and histological activity indices (HAI) were blindly examined by two independent observers. For comparison, we examined histological changes of pre- and posttreatment liver biopsies of 19 patients who were treated by recombinant interferon for chronic hepatitis B. Mean HAI scores improved from 10.0 to 5.4 after treatment in non-A, non-B chronic hepatitis. The most marked reduction was noted in scores of portal inflammation and hepatocellular degeneration and/or necrosis. No such reduction was observed in B- viral chronic hepatitis. These data indicated that rapid biochemical resolution by the treatment was related to histological improvement of the liver in our patients with non-A, non-B hepatitis.

Randomized, double-blind, placebo-controlled trial of eight-week course of recombinant α-interferon for chronic non-A, non-B hepatitis

Forty-nine Japanese patients were enrolled in a randomized, placebo-controlled, doubleblind trial of α-interferon for chronic non-A, non-B hepatitis: 24 patients received 3 million units of recombinant human alpha α-interferon (α-2a) thrice weekly for eight weeks, and 25 patients received placebo in a similar schedule. The mean serum alanine aminotransferase (ALT) dropped from 155±91 (sd) to 69±72 during interferon treatment, but remained unchanged (158±140 to 147±130) during placebo treatment (P<0.001). Serum ALT level fell to the normal range in 29% of interferon-treated patients, but in only 4% of placebo-treated patients. Pre- and posttreatment liver biopsies were obtained in all but one case. Average histological activity indices (HAI) were markedly improved in the interferon-treated group (9.5±3.7 to 7.0±4.3), but were unchanged in the placebo group (8.5±4.3 to 8.5±4.9). In addition, we compared the efficacy of interferon treatment between anti-hepatitis C virus (HCV) antibody positive and negative groups. Biochemical and histological improvements were similar and statistically significant in patients with and without antibody to hepatitis C virus. These data indicate that a eight-week course of α-interferon induces biochemical and histological improvement in more than half the patients with chronic non-A, non-B hepatitis.

Detection and direct sequencing of hepatitis B virus genome by DNA amplification method

Hepatitis B virus (HBV) DNA was detected with amplification by the polymerase chain reaction method. Cloned HBV DNA equivalent to one virus genome (3 x 10(-6) pg) was detectable by ethidium bromide staining after 50 cycles of polymerase chain reaction. By applying this method, presence of HBV DNA was studied in 23 hepatitis B surface antigen (HBsAg)-positive and 11 HBsAg-negative sera from patients with chronic liver disease. Hepatitis B virus DNA was positive in 8 of 8 hepatitis B e antigen (HBeAg)-positive, in 2 of 2 HBeAg- and anti-HBe-negative, and in 12 of 13 anti-HBe-positive sera. Hepatitis B virus DNA was undetectable in all HBsAg-negative sera even with amplification. To confirm specificity, the amplified product was directly sequenced. Sequences around 122nd and 160th codon of HBs gene, which determines subtypes d/y and w/r, respectively, were analyzed. The results were compatible with recent reports regarding the relation between HBV subtypes and HBV DNA sequence at those codons. Hepatitis B virus DNA could be detected at the level of one virion by gene amplification method, and its sequence could be determined by direct sequencing in a few days.

Efficacy of longterm interferon treatment in chronic liver disease evaluated by sensitive polymerase chain reaction assay for hepatitis C virus RNA.

Effects of interferon treatment on hepatitis C virus were examined by investigating the presence of hepatitis C virus ribonucleic acid and anti-hepatitis C virus antibody in 70 patients with non-A, non-B chronic liver diseases. Twenty one patients were treated with three million units of interferon alfa 2a three times a week for 52 weeks, 24 patients were treated similarly for eight weeks, and 25 patients were given a placebo for eight weeks and served as control. Sixty six of 70 patients (94%) were positive for both hepatitis C virus RNA and second generation anti-hepatitis C virus antibody. Fourteen of 21 (67%) receiving the longterm treatment had a normalised alanine aminotransferase (ALT) activity, and in 12 of these hepatitis C virus ribonucleic acid became undetectable by the end of treatment and remained so during the three year follow up after the treatment. Anti-hepatitis C virus antibody determined by first generation assay became negative in one case at the end of the 52 week treatment, and in four cases at the end of the one year follow up. In contrast, only one of 24 (4%) who received the eight week treatment and only one of 25 (4%) who received the placebo had normalised ALT activities. Hepatitis C virus ribonucleic acid became negative in two patients undergoing short-term treatment and in none receiving the placebo. Thus, longterm interferon treatment seems effective in clearing hepatitis C virus from serum of patients with chronic liver disease.

Detection and partial sequencing of hepatitis C virus RNA in the liver

To detect hepatitis C virus RNA, total RNA was extracted from liver tissue, reverse transcribed to complementary DNA, and amplified by polymerase chain reaction. The reaction products were analyzed by ethidium bromide staining in acrylamide gel and hybridization with a radiolabeled probe. Hepatitis C virus RNA was thereby detected in 17 of 27 (63%) liver tissue specimens obtained from patients with non-A, non-B chronic liver diseases. Of these 27 patients, viral RNA was detected in 12 of 17 (71%) liver tissues from anti-hepatitis C virus-positive patients and in 5 of 10 (50%) liver tissues from anti-hepatitis C virus-negative patients. Direct sequencing of amplified complementary DNA (35 nucleotides) of the 17 RNA-positive samples showed only 66% to 77% homology to the reported hepatitis C virus complementary DNA sequence. These results indicate that the majority of anti-hepatitis C virus-positive patients are currently infected with hepatitis C virus, and some of the anti-hepatitis C virus-negative patients with non-A, non-B hepatitis are harboring hepatitis C virus in the liver. Detection of hepatitis C virus RNA appears to provide a useful indicator in the study of hepatitis C virus infection.