Serological responses to infection with three different types of hepatitis C virus

Virological features of hepatitis C virus infection in hemodialysis patients

The clinical and epidemiological relevance of circulating antibodies to hepatitis C virus (HCV) in hemodialysis patients is uncertain, since clinical signs of infection are often mild or absent, with alanine aminotransferase (ALT) values that are virtually always normal, and liver biopsies are only rarely performed. Determination of HCV RNA in serum is therefore critical for distinguishing chronic HCV infection from previous exposure to the virus. We studied HCV viremia by reverse transcription polymerase chain reaction (RT-PCR) in the 5'-noncoding region of the viral genome in 77 dialysis patients who were screened for anti-HCV by a second-generation enzyme-linked immunosorbent assay (the enzyme immunoassay II; Ortho HCV, 2nd generation, Ortho Diagnostic Systems Raritan, N.J.) and a second-generation recombinant immunoblot assay (Chiron Corporation and Ortho Diagnostic Systems) and prospectively evaluated for ALT elevations over a period of 5 years. Of 77 patients tested, 29 (38%) had active infection as shown by a positive PCR assay result, and of these, 26 were anti-HCV positive. Although a good correlation was found between circulating anti-HCV and HCV RNA in serum, 10 (28%) of 36 anti-HCV-positive patients were HCV RNA negative by PCR, suggesting either low levels of viremia or past exposure to HCV and subsequent recovery. On the other hand, 3 (7.3%) of 41 anti-HCV-negative patients had HCV RNA in their sera, indicating seronegative HCV infection. The ALT level had no predictive value for HCV infection, because it was repeatedly normal in 18 (62%) of 29 viremic patients. HCV genotyping was also performed and indicated that all four known genotypes of HCV were present in our group. In conclusion, serological assays are reliable for detecting exposure to HCV in hemodialysis patients; however, direct identification of the viral genome is required to document current infection.

Genotype dependence of hepatitis C virus antibodies detectable by the first-generation enzyme-linked immunosorbent assay with C100-3 protein

Hepatitis C virus (HCV) samples in 155 sera, from patients with chronic non-A, non-B liver disease and blood donors, were grouped into four genotypes (I, II, III, and IV) by amplification of core-gene sequences by polymerase chain reaction with type-specific primers. HCV genotypes were compared with various HCV-associated antibodies detectable by the first-generation ELISA (ELISA-1) with C100-3 protein and a second-generation immunoblot assay with four recombinant HCV proteins. Antibodies to C100-3 protein and those to its subsequence (5-1-1) were detected in 13 (93%) and 12 (86%), respectively, of 14 sera with genotype I HCV; 56 (79%) and 58 (82%) of 71 sera with genotype II; 13 (34%) and 6 (16%) of 38 sera with genotype III; and 11 (34%) and 4 (13%) of 32 sera with genotype IV. Amino acid sequences of C100-3 of genotype I HCV are conserved by approximately 90% in genotype II, but only by approximately 75% in genotypes III and IV. The sensitivity of ELISA-1, therefore, would be influenced by heterogeneity in C100-3 sequences of different genotypes.

Hepatitis C antibodies in dialysis patients and patients with leukaemia

The prevalence of hepatitis C antibodies (anti-HCV) among multitransfused patients was studied and compared with predicted values obtained from a post-transfusion hepatitis study and from data on the prevalence of anti-HCV among blood donors. The prevalence of hepatitis B core antibodies (anti-HBc) was also studied to determine the routes of transmission of hepatitis C virus. The patients consisted of 65 dialysis patients (57 on haemodialysis and 8 on continuous ambulatory peritoneal dialysis) and 71 leukaemia patients in long-term remission [49 with acute myeloid leukaemia (AML) and 22 with acute lymphatic leukaemia (ALL)]. The presence of anti-HCV was investigated using a second generation enzyme-linked immunosorbent assay. Reactive samples were confirmed by a second generation recombinant immunoblot assay. Anti-HBc was studied in the 65 dialysis patients and in 40 of the leukaemia patients. Three (4.6%) of the 65 dialysis patients and 12 (24.5%) of the 49 AML patients were anti-HCV positive whereas all of the ALL patients were seronegative. The total number of blood units transfused to 134 patients (data on two dialysis patients were not available) was 18,148, out of which 17,575 units had been transfused prior to the initiation of anti-HCV screening of blood donors. On the basis of the anti-HCV prevalence among blood donors and the incidence of post-transfusion hepatitis, the predicted number of seropositive patients was 11 and 18, respectively. Five of the 65 dialysis patients were anti-HBc positive, compared with only one of the 40 leukaemia patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence, genotypes, and an isolate (HC-C2) of hepatitis C virus in Chinese patients with liver disease

China has not been extensively investigated for the prevalence of hepatitis C virus (HCV) infection among people with or without liver disease. We analyzed serum from 2,177 liver disease patients from 7 cities in different areas of China. Of 435 acute hepatitis patients, only 11% were positive for HCV RNA, while hepatitis B surface antigen (HBsAg) was detected in 33%. Of 1,668 patients with chronic liver disease, 14% and 74% were positive for HCV RNA and HBsAg, respectively. Nearly 80% of non-B chronic liver disease were negative for HCV RNA. The frequency of HCV RNA in chronic liver disease was significantly higher in Hami (32%) and Shenyang (30%) than in other cities (6-12%). The HCV genotype distribution varied by region. Genotype III was detected in 46-70% of HCV infections in Hami, Shenyang, and Lanzhou, while more than 90% of patients from southern cities (Nanjing, Nanning, and Chengdu) had genotype II. No evidence for genotype I or IV infections was found. A full-length HCV genome sequence (HC-C2) derived from a Beijing patient with genotype II was closely related to previous isolates from Japanese and Taiwanese patients. These results suggest that HCV prevalence and genotype distribution vary from region to region in China, and that the HCV now predominant in China may have evolved epidemiologically with infections in Japan and Taiwan. The study identified a high frequency of non-B, non-C chronic liver disease in China, suggesting possibly a new agent or infections with extreme variants of HCV.

Second-generation hepatitis C Elisa antibody tests confirmed by the four-antigen recombinant immunoblot assay correlate well with hepatitis C viremia and chronic liver disease in Swedish blood donors

Seventy-three Swedish blood donors (52 men, 21 women; median age 36 years) repeatedly reactive for hepatitis C antibodies (anti-HCV C-100-3) were tested with a second-generation (2nd-gen) anti-HCV Elisa and a 4-band recombinant immunoblot assay (RIBA 2). These results were correlated to serum alanine aminotransferase (S-ALAT), liver morphology and viremia as detected by 'nested' polymerase chain reaction (PCR) based on primers from a 5'-noncoding sequence of the HCV genome. Thirty-five of 46 (76%) donors with positive 2nd-gen Elisa tests confirmed by RIBA 2 were PCR positive whereof 27 had histological findings compatible with chronic persistent hepatitis (CPH) and 7 had chronic active hepatitis (CAH). Ten of 56 (18%) 2nd-gen Elisa-positive donors were RIBA 2 negative (or indeterminate) and none of these had chronic hepatitis nor were PCR positive. Seventeen of 73 (23%) donors were 1st-gen Elisa positive but 2nd-gen Elisa negative. All of these were PCR negative and only 1 (6%) had chronic hepatitis (CPH). An elevated S-ALAT level (reference < 0.7 mu kat/l) was found in 26 2nd-gen Elisa and RIBA 2-positive donors of which 18 had CPH and 7 had CAH and all 25 were PCR positive. A normal S-ALAT level was found in 9 of 34 (26%) donors with chronic hepatitis (all had CPH) and positive PCR. We have found that blood donors with positive 2nd-gen anti-HCV Elisa tests confirmed by RIBA-2 and especially with a concomitant elevated S-ALAT are highly likely to be viremic as demonstrated by PCR and to have chronic hepatitis.

Mapping of serotype-specific, immunodominant epitopes in the NS-4 region of hepatitis C virus (HCV): use of type-specific peptides to serologically differentiate infections with HCV types 1, 2, and 3

The effect of sequence variability between different types of hepatitis C virus (HCV) on the antigenicity of the NS-4 protein was investigated by epitope mapping and by enzyme-linked immunosorbent assay with branched oligopeptides. Epitope mapping of the region between amino acid residues 1679 and 1768 in the HCV polyprotein revealed two major antigenic regions (1961 to 1708 and 1710 to 1728) that were recognized by antibody elicited upon natural infection of HCV. The antigenic regions were highly variable between variants of HCV, with only 50 to 60% amino acid sequence similarity between types 1, 2, and 3. Although limited serological cross-reactivity between HCV types was detected between peptides, particularly in the first antigenic region of NS-4, type-specific reactivity formed the principal component of the natural humoral immune response to NS-4. Type-specific antibody to particular HCV types was detected in 89% of the samples from anti-HCV-positive blood donors and correlated almost exactly with genotypic analysis of HCV sequences amplified from the samples by polymerase chain reaction. Whereas almost all blood donors appeared to be infected with a single virus type (97%), a higher proportion of samples (40%) from hemophiliacs infected from transfusion of non-heat-inactivated clotting factor contained antibody to two or even all three HCV types, providing evidence that long-term exposure may lead to multiple infection with different variants of HCV.

Association of hepatitis C virus infection with chronic liver disease in paediatric cancer patients

A total of 203 paediatric cancer treatment survivors were tested for serum antibodies against hepatitis-C virus (anti-HCV). Anti-HCV was detected in 41 patients (20.2%) with first generation anti-HCV ELISA. Positive results were confirmed in all samples retested with a second generation ELISA (n = 35) and in all but two cases re-analysed by immunoblotting (n = 23). Anti-HCV positive children had received significantly more blood product transfusions compared to seronegative patients. In 75 children (32%) chronic liver disease was found. It was defined as an elevation of serum alanine aminotransferase values to a least 2.5 times the upper limit of normal persisting for 6 months or longer. Hepatitis A was never detected, and in 58 children the chronic hepatopathy was unexplained by hepatitis B (non-A non-B chronic liver disease). Of these patients 29 (50%) were seropositive for anti-HCV. Surprisingly, non-A/non-B chronic liver disease was associated with anti-HCV in 14 of 19 solid tumour patients (78.9%), but in no more than 14 of 39 leukaemia and lymphoma patients (35.9%). This phenomenon was not explained by different rates of cytomegalovirus disease and drug toxicity related hepatopathies between the two groups. It may be related to differences of leukaemia/lymphoma compared to solid tumour therapy schedules (differential immunosuppression and liver toxicity).

Hepatitis C virus (HCV) RNA among anti-HCV-positive blood donors and their recipients

Seven of 24 blood donors positive in Ortho's first-generation antibody to hepatitis C virus (anti-HCV) test (EIA-1) were also positive in Ortho's second-generation test (EIA-2). All 7 had at least two anti-HCV positive recipients, whereas only 1 of the 17 EIA-2-negative donors had an anti-HCV-positive recipient. This recipient was a multitransfused patient with von Willebrand's disease. Five of the 7 EIA-2-positive donors had detectable HCV RNA. We traced and tested 38 of the still living blood recipients from the 7 EIA-2-positive donors. Twenty-eight of these were EIA-2 positive and 22 were HCV-PCR positive. One patient with Waldenstroem's hypergammaglobulinemia was EIA-2 negative but HCV-PCR positive. All the EIA-2-positive sera showed reactivity in Ortho's recombinant immunoblot assay (RIBA-2), but 5 of the 28 recipients and 1 of the donors reacted with only one band (RIBA-2 indeterminate). Among 32 recipients who probably had received EIA-2-positive blood, 29 (91%) had markers of an HCV infection. Twenty-two (75%) of the HCV-infected recipients had detectable HCV RNA more than 6 months after transfusion and hence were chronic HCV carriers.

Improved detection of antibodies to hepatitis C virus by the second-generation assay in patients with chronic non-A, non-B liver disease

Serum samples from 337 Japanese patients with chronic non-A, non-B liver disease were tested for antibodies to hepatitis C virus (HCV) by means of first-generation (c100-3; anti-c100) and second-generation (pHCV-34, pHCV-31, c100-3; anti-HCV II) enzyme linked immunosorbent assays (ELISA) and for antibody to the GOR epitope (anti-GOR) also by ELISA. Anti-HCV II was detected in 314 (93.2%), anti-c100 in 247 (81.3%) and anti-GOR in 211 (62.6%) samples. Thus, anti-HCV II was more sensitive in detecting HCV infection than either anti-c100 or anti-GOR (P < 0.001). All serum samples reactive with anti-c100 or anti-GOR reacted with anti-HCV II. Among 314 anti-HCV II-positive patients, we found that 185 (58.9%) were positive for both anti-c100 and anti-GOR while 14 (4.5%) were positive for anti-HCV II alone. Nine (64.3%) of the 14 are presently infected with HCV, as revealed by detection of HCV RNA in their serum; the remaining five may have been infected in the past with HCV. These findings indicate that HCV is a major causative agent of chronic non-A, non-B liver disease in Japan and that detection of anti-HCV II is a specific and more sensitive diagnostic test for HCV infection.

Hepatitis C virus infection in African patients with liver cirrhosis or primary hepatocellular carcinoma

We have studied the prevalence of hepatitis C virus (HCV) infection in Rwandan patients with histologically proven liver cirrhosis (LC) or primary hepatocellular carcinoma (HCC). Anti-HCV antibodies were determined by using a second-generation test, with a line immunoassay for structural and non-structural antigens as confirmation. Seventy-nine patients with LC, 26 with HCC, and 54 voluntary blood donors as controls were evaluated. Anti-HCV antibodies were more prevalent in LC patients (48%) and in HCC patients (38%) than in the controls (17%; difference, p = 0.0001 and p = 0.03, respectively). Eighty-four per cent of LC patients and 54% of HCC patients were HBsAg-negative. The prevalence of anti-HCV antibodies was significantly higher for LC and HCC patients who had been in contact with HBV but who had no persistent HBV infection (p < 0.05). We conclude that HCV infection is common in Rwanda and is linked to LC and HCC.

Prevalence of HCV-RNA-positive blood donors and correlation to ELISA and RIBA status

In Germany, transmission of hepatitis C virus by blood transfusion is prevented by screening the donations for anti-HCV and ALT. The specificity of the anti-HCV screening in low seroprevalence populations has been questioned. In order to evaluate this screening policy we wanted to estimate the prevalence of viremic and potentially infectious donors by the HCV-RNA polymerase chain reaction (PCR) in our donor population of southern Germany. Donors (n = 301) were divided into four subgroups according to anti-HCV status and ALT levels. HCV sequences were detected by nested PCR, using primers for the most conserved region of the viral genome. The recombinant immunoblot assay (RIBA-4) was applied to the same samples. PCR detected 4.2% HCV-RNA carriers in the subgroup anti-HCV-/ALT-; 3% in the subgroup anti-HCV-/ALT+; 19.4% in the subgroup anti-HCV+/ALT-; and 59.4% in the subgroup anti-HCV+/ALT+. It was concluded that, on the one hand, the lack of specificity of the anti-HCV ELISA gives rise to many false-positive results; on the other hand, a minority of infected donations will not be detected by the screening procedure. ALT in conjunction with anti-HCV improves the quality of screening for potentially infectious donors.

Isolate antibody to hepatitis C virus core antigen (C22) by RIBA-2: correlation with HCV-RNA and anti-NS5

The presence of circulating hepatitis C virus genome (HCV-RNA), elevated ALT levels and antibodies to an NS5-derived synthetic peptide have been examined in 13 subjects with isolate positivity for antibodies to the HCV core antigen (C22) on RIBA-2 testing. All subjects were followed up for 8-18 months (mean 12.4 months). In seven subjects (54%), intermittent or persistent viremia was associated with abnormal ALT levels (6 subjects) and with positivity for antibodies to NS5-peptide (6 subjects). On the other hand, in 6 out of 13 subjects (46%) no viral replication, no liver cytonecrosis and no antibodies to NS5 were found. It is concluded that isolate reactivity to C22 by RIBA-2 is a heterogeneous condition that corresponds to two distinct categories of subjects: those with active HCV infection and those without evidence of virus replication. Although HCV-RNA determination is the most reliable means of identifying HCV carriers, antibodies to NS5 can be a useful marker of virus activity. In fact, antibodies to NS5 were detected in 6 out of 7 viremic patients, compared to 0 out of 6 non-viremic patients (P = 0.004). It remains to be elucidated whether the isolate reactivity to core antigen found in non-viremic subjects represents a specific, HCV-induced antibody response, or is an unrelated crossreactivity.

Full-length sequence of a hepatitis C virus genome having poor homology to reported isolates: comparative study of four distinct genotypes

Variable genomic sequences have been reported for RNA cloned from hepatitis C virus (HCV)-infected humans and chimpanzees. We found that four distinct genotypes of HCV could be differentially identified by PCR using type-specific primers. Full-length sequences have so far been reported for three of the four HCV genotypes, and we report herewith the sequence of the fourth type obtained from a Japanese blood donor. The entire nucleotide sequence of the HCV isolate (HC-J8) comprised 9481 bases plus a 3'-terminal poly(U) stretch of variable length. Like all previous isolates, the RNA contained a single, long open reading frame for a polyprotein of 3033 amino acids. HC-J8 differed from previously reported HCV isolates by 23.1-33.1% in nucleotide sequence and 15.9-28.8% in amino acid sequence. Based on genomic sequence homologies, a proposed phylogenetic tree of HCV, with a fourth branch represented by HC-J8, allowed a classification of all HCV isolates whose complete or partial sequences are now known. This classification suggests that all or most HCV genome sequences will fall into one of the proposed four types. The classification may be helpful in designing vaccine studies and for serological investigations of possible group- and type-specific antibodies.