Anti-Hepatitis C Virus Screening Will Reduce the Incidence of Post-Transfusion Hepatitis C Also in Low-Risk Areas

The incidence of post-transfusion hepatitis non-A, non-B (PTH-NANB) was prospectively assessed in two areas in the southeast region of Sweden. Patients undergoing hip arthroplasty were studied with blood sampling for alanine aminotransferase analysis before and at 2, 3, and 4 months after transfusion. Of the patients 97% and 82% were transfused and received a mean of 5.5 and 3.4 units in Linköping and Oskarshamn, respectively. None of 38 patients in Oskarshamn but 4 of 144 patients (2.8%) in Linköping contracted PTH-NANB. Two of these four patients developed antibodies against hepatitis C virus (HCV) by the first-generation anti-HCV enzyme-linked immunosorbent assay (ELISA) (C100). The other two patients remained negative by this test. HCV infection was, however, indicated in all four patients by positive second-generation anti-HCV ELISA confirmed by positive second-generation recombinant immunoblot assay (4-RIBA). Three of the patients were positive by polymerase chain reaction (PCR). Serum from one blood donor to the four hepatitis patients (altogether three donors) was found positive by first- and second-generation anti-HCV ELISA and 4-RIBA and was also PCR-positive. Three other blood donors, who did not transmit hepatitis, were anti-HCV ELISA (C100)-positive. This study shows that if anti-HCV ELISA had been available at the start of the trial, all cases of PTH would have been avoided at the expense of only 0.7% transfusion units discarded. Routine anti-HCV ELISA testing of all transfusion units will reduce the incidence of PTH-C even in low-risk areas.     

Anti-hepatitis C virus screening will reduce the incidence of post-transfusion hepatitis C also in low-risk areas.

The incidence of post-transfusion hepatitis non-A, non-B (PTH-NANB) was prospectively assessed in two areas in the southeast region of Sweden. Patients undergoing hip arthroplasty were studied with blood sampling for alanine aminotransferase analysis before and at 2, 3, and 4 months after transfusion. Of the patients 97% and 82% were transfused and received a mean of 5.5 and 3.4 units in Link?ping and Oskarshamn, respectively. None of 38 patients in Oskarshamn but 4 of 144 patients (2.8%) in Link?ping contracted PTH-NANB. Two of these four patients developed antibodies against hepatitis C virus (HCV) by the first-generation anti-HCV enzyme-linked immunosorbent assay (ELISA) (C100). The other two patients remained negative by this test. HCV infection was, however, indicated in all four patients by positive second-generation anti-HCV ELISA confirmed by positive second-generation recombinant immunoblot assay (4-RIBA). Three of the patients were positive by polymerase chain reaction (PCR). Serum from one blood donor to the four hepatitis patients (altogether three donors) was found positive by first- and second-generation anti-HCV ELISA and 4-RIBA and was also PCR-positive. Three other blood donors, who did not transmit hepatitis, were anti-HCV ELISA (C100)-positive. This study shows that if anti-HCV ELISA had been available at the start of the trial, all cases of PTH would have been avoided at the expense of only 0.7% transfusion units discarded. Routine anti-HCV ELISA testing of all transfusion units will reduce the incidence of PTH-C even in low-risk areas.     

Early Antihepatitis C Virus Response with Second—Generation C200/C22 ELISA

Detection of early antibody to hepatitis C virus (HCV) by a new second-generation C200/C22 anti-HCV enzyme-linked immunosorbent assay (ELISA) and a four-antigen recombinant immunoblot assay (4-RIBA) was compared with the first-generation anti-HCV C100 ELISA using sequential serum samples of 9 recipients who were infected with HCV, as detected by polymerase chain reaction after transfusion of blood products. Within 26 weeks after transfusion, 9/9 (100%) recipients seroconverted with C200/22 ELISA, and 6/9 (67%) seroconverted with C100 ELISA. Compared with C100 ELISA, C200/C22 ELISA seroconversion occurred simultaneously in 3 cases, 5-6 weeks earlier in 3 other cases, and 20 weeks earlier in 1 case. Seven of 9 (78%) recipients became positive, and 2/9 (22%) became indeterminate with 4-RIBA. In 8 cases with clinical posttransfusion hepatitis non-A, non-B (PTH-NANB), anti-HCV C200/C22 ELISA seroconversion occurred 2-17 (mean 6) weeks after the onset of hepatitis. In 6 cases of PTH-NANB, anti-HCV C100 ELISA seroconversion occurred 2-26 (mean 9) weeks after the onset of hepatitis. It is concluded that the second-generation C200/C22 ELISA is more sensitive than the C100 ELISA for the detection of antibody during early HCV infection. Indeterminate 4-RIBA results are found in the early phase of HCV infection.     

Comparison of two second-generation anti-hepatitis C virus ELISA on 21431 US blood donor samples

SUMMARY. We have compared two different second-generation (2.O) enzyme-linked immunosorbent assays (ELISA) for the presence of antibodies to hepatitis C virus (anti-HCV) in blood from volunteer, unpaid donors. At two separate blood centres, a total of 21431 donor samples were tested with Abbott Anti-HCV 2.0 ELISA and Ortho Anti-HCV 2.0 ELISA. Samples found to be repeatedly reactive were tested by supple-mental/investigational assays, MATRIX HCV (Abbott) and anti-HCV RIBA II (Ortho/Chiron), to 'confirm' the presence of anti-HCV. Discordant ELISA samples were additionally tested by the polymerase chain reaction (PCR) for the presence of HCV RNA. The Abbott anti-HCV assay had a repeatedly reactive rate of 0.59% (127/21431) and the Ortho anti-HCV assay 0.51% (110/21431). Overall agreement between assays was 99.76%. 72/127 (56.7%) of Abbott repeatedly reactive samples confirmed on MATRIX and 61/127 (48.0%) on RIBAII; 70/110 (63.6%) of Ortho repeatedly reactivate samples confirmed on MATRIX and 61/110 (55.5%) on RIBA II. Discordant ELISA samples tested by PCR yielded negative results. Hence the two ELISA had equal sensitivity, as defined by detection of true positive samples: the slightly lower specificity of the Abbott Anti-HCV 2.0 ELISA may be owing to culling of donors with a false positive test by Ortho's Anti-HCV 1.0 and 2.0 ELISA tests (the routine tests in place at each blood centre). A sample found to be repeatedly reactive by two different ELISA tests for anti-HCV is likely to be a true positive and may not require further 'confirmatory' testing.     

Epidemiology,serological markers,and hepatic disease of anti-HCV ELISA-2-positive blood donors

The epidemiology associated with hepatitis C virus (HCV) infection, serologic reactivity, and hepatic disease related to anti-HCV-positive donors of Granada were researched. From 1990 through 1993, medical and epidemiological information and anti-HCV and HCV RNA testing were evaluated in 46,741 blood donors. Serum samples were obtained for anti-HCV ELISA and RIBA and HCV RNA determination. A liver biopsy was conducted in all anti-HCV positives by confirmatory second-generation RIBA to analyze the hepatic lesion and the presence of HCV RNA. The anti-HCV prevalence was 1.12%. A total of 228 anti-HCV second-generation ELISA positive blood donors were analyzed. Intrafamiliar transmission rate was 1.7%. Transfusion and intravenous drug abuse (IVDA) antecedents were associated with a higher risk of seroconversion. A RIBA-positive result was related to high second- and third-generation ELISA ratios (90%), HCV RNA positivity (89%), and elevated alanine aminotransferase (ALT) levels (88%). Approximately 50% of donors with normal ALT levels had high ELISA ratios and second-generation RIBA and HCV RNA positive results. Of the second-generation RIBA indeterminate results, 42% and 82% of the c22 and 33% and 100% of the c100 reactivities were third-generation RIBA and HCV RNA positive, respectively. Liver biopsy was conducted in 85 donors, 74% of whom had a chronic hepatitis and 83% had detectable HCV RNA levels. Chronic hepatitis was diagnosed in 88% vs 43% of donors with elevated and normal alanine aminotransferase levels, respectively. ELISA and confirmatory HCV RNA determinations should be routinely employed in donor screening. A liver biopsy should be conducted in patients with elevated ALT levels and normal ALT levels when viremic.     

Outcome of acute symptomatic non-A,non-B hepatitis: a 13-year follow-up study of hepatitis C virus markers

ABSTRACT— Thirty-nine of 61 prospectively followed patients who had had acute non-A, non-B hepatitis in 1978 were clinically reexamined in 1991 and tested for antibodies to hepatitis C virus (anti-HCV) with a second generation ELISA and RIBA and for HCV RNA by PCR. Acute hepatitis C was diagnosed in stored sera from 1978 in 24 patients, who were found still to be anti-HCV positive in 1991, and 16 of them were also HCV RNA positive. The majority of anti-HCV positive patients with or without HCV RNA had elevated serum ALT levels 13 years after onset of their acute hepatitis C. After 13 years follow-up, 1.6% of the patients had died of end-stage liver disease, 8% of anti-HCV positive patients had histologically confirmed liver cirrhosis, 79% of anti-HCV positive patients were judged to have chronic infection, whereas 21% seemed to have recovered. To conclude, we found that a majority of our patients with acute symptomatic hepatitis C continued to be viraemic 13 years after onset of hepatitis C, and that all continued to be anti-HCV positive by second-generation ELISA.     

Evidence that use of a second-generation hepatitis C antibody assay prevents additional cases of transfusion-transmitted hepatitis

SUMMARY. The aim of this study was to determine if using hepatitis C antibody (anti-HCV) enzyme immunoassay version 2.0 (EIA2) in addition to version 1.0 (EIA1) increased the safety of the blood supply. Blood non-reactive by anti-HCV EIA1 was transfused in 1990-92. Stored samples from 40098 units, donated prior to 13 March 1992 were later tested by EIA2. For donor units reactive for anti-HCV by EIA2. a recombinant immunoblot assay (RIBA2) was also carried out. In 63 cases, recipients of transfusions which were EIAZ negative or EIA2 reactive were tested for anti-HCV and elevated alanine aminotransferase (ALT) levels 9-1 2 months after transfusion: pretransfusion anti-HCV status of recipients was unknown. Among these multitransfused patients receiving units that were negative by both EIA1 and EIA2, 1/26 (4%) had anti-HCV. Among transfusion recipients of units negative by EIA1, but who received at least one unit reactive by EIA2,4/37 recipients (11%) were anti-HCV reactive (P = 0.59). For the recipients of EIA2 reactive blood, when the donor unit was RIBA2 non-reactive. 0/23 recipients were reactive by anti-HCV. Among the recipients of a RIBA2 indeterminate unit, 1/10 recipients had anti-HCV, but for patients who received at least one RIBA2 reactive unit, 3/4 recipients had anti-HCV (P = 0.0 3). Hence. second-generation anti-HCV testing detected additional units capable of transmitting hepatitis C that were not detected by first-generation testing. However, RIBA2 is a more specific method than EM2 for determining units capable of transmitting HCV.     

High rate of nonspecific anti-hepatitis C reactivity amongst homosexual men in comparison with that found in other sexually active groups and blood donors

Abstract. Objectives . To investigate the concordance of antihepatitis C virus (anti-HCV) reactivity by a second-generation enzyme immunoassay (EIA-2) and by a four-antigen recombinant immunoblot assay (4-RIBA) in homosexual men, in comparison with that found in other sexually active groups and blood donors. Design . Prospective study. Setting . Tertiary referral centre, Seville, Spain. Subjects . A total of 1203 subjects were studied. Eight hundred and three were sexually active individuals: 547 female prostitutes, 88 heterosexual men who had frequent sexual intercourse with prostitutes, and 168 homosexual men. All of them denied blood transfusion and parenteral drug use. In addition, 400 voluntary blood donors were selected at random. Main outcome measures . All serum samples were screened for anti-HCV by EIA-2 and repeatedly reactive sera were tested by 4-RIBA. Homosexual men were also screened for anti-human immunodeficiency virus (anti-HIV), hepatitis B virus (HBV) markers and gammaglobulin concentration. Finally, serum samples from homosexual men reactive for anti-HCV by EIA-2 were analyzed for HCV-RNA by polymerase chain reaction (PCR). Results . Concordance between EIA-2 and 4-RIBA in female prostitutes (71.4%), clients of prostitutes (75.0%), and blood donors (83.3%) was significantly higher than in homosexual men (38.8%) (P < 0.04). In this collective the concordance between 4-RIBA and PCR was 85.7% for positive cases and 88.8% for negative ones, and EIA-2 ratios in reactive sera were significantly higher in 4-RIBA confirmed cases (P < 0.0001). No correlation between false positive EIA-2 results and presence of HIV infection, HBV markers or hypergammaglobulinaemia was found in homosexual men by univariate analysis. Conclusions . There is a high level of non-specific anti-HCV reactivity by EIA-2 amongst homosexual men in comparison with that found in other sexually active groups and blood donors. The true prevalence of HCV infection amongst homosexual men could be even lower than previously described.     

Prevalence of hepatitis C virus infection in asymptomatic anti-HIV1 negative pregnant women and their children

The prevalence of hepatitis C virus (HCV) infection was studied prospectively in pregnant women in France and their children by detection of anti-HCV with second-generation ELISA (ELISA2). In ELISA2-positive women, anti-HCV was detected with second- and third-generation RIBA (RIBA2 and RIBA3) and serum HCV RNA was detected with PCR. Among 670 women, anti-HIV1-negative, 26 (3.9%) were positive with ELISA2. RIBA2 was positive in 13 and HCV RNA was found in 10. Ten ELISA2-positive women had a further evaluation with assessment of HCV infection in their children. Among the 10 children born to the index pregnancy, only one was positive with ELISA2 and RIBA2 but negative with RIBA3 and PCR; the nine other children were ELISA2, RIBA2, RIBA3, and PCR negative. All 26 siblings (2–16 years old), of whom 14 were born to PCR-positive mothers, were ELISA2 and RIBA2 negative. We conclude that among anti-HIV1-negative pregnant women with normal serum ALT levels, the prevalence of HCV infection is relatively high but the risk for mother-to-infant transmission of HCV seems to be low.     

Prospective assessment of donor blood screening for antibody to hepatitis C virus by first- and second-generation assays as a means of preventing posttransfusion hepatitis

In November 1989, the Japanese Red Cross began screening blood donors for the hepatitis C virus antibody (anti-HCV) by first-generation assay and high-titer hepatitis B virus core antigen antibody. A significant reduction in the incidence of acute posttransfusion hepatitis was reported; however, the incidence still ranged from 2 percent to 4 percent. The Red Cross changed to the second-generation assay in February 1992, the objective being the complete elimination of potential posttransfusion hepatitis. The aim was to elucidate the advantage of second-generation assay as a blood-donor screening test. The incidence of posttransfusion hepatitis after the introduction of second-generation assay was compared with that before the introduction of the first-generation assay and with that during its use. The incidence of posttransfusion hepatitis was 9.6 percent (216/2,240) before anti-HCV-s donor screening. It was 3.7 percent (24/655) and 0.9 percent (3/326) after the introductions of the first-and second-generation hepatitis C virus (HCV) assays, respectively (chi² = 50.0, P < .01). Blood-donor screening by second-generation anti-HCV provided a significant benefit compared with the first-generation assay. (Hepatology 1996 Apr;23(4):708-12)     

A case of transfusion-acquired hepatitis C

Summary The Blood Transfusion Service introduced screening for Hepatitis C antibody (HCV) in September 1991. This is done by second generation enzyme linked immunosorbent assay (ELISA) tests. We present a case of post-transfusion hepatitis C hepatitis in a patient with myeloma. Infection was acquired before screening was introduced. Both the patient and the infected blood donor were diagnosed using ELISA assays and the polymerase chain reaction (PCR). In this way we prevented the blood donor from spreading the virus via subsequent blood donations. There were some interesting discrepancies in the HCV assays. Blood samples, when tested by different methods, gave both positive and negative results. The results also varied according to when the blood samples to be tested were taken. The case illustrates the importance of confirming positive results and that no single laboratory test is entirely satisfactory in diagnosing HCV infection.     

Chronic hepatitis C without anti-hepatitis C antibodies by second-generation assay

To study the clinicopathologic features of hepatitis C viremic patients negative for hepatitis C antibodies (anti-HCV) by current second-generation assay, we categorized 139 consecutive histologically verified patients with chronic non-A, non-B hepatitis into three groups: 121 (87%) were positive for second-generation anti-HCV (group A); 10 (7%) were negative for second-generation anti-HCV but positive for HCV RNA (group B); and 8 (6%) were negative for both antibodies and viremia (group C). Six (60%) of group B patients could be further detected by a new third-generation assay, but none of group C patients was third-generation anti-HCV-positive. The demographic features, mean peak serum alanine aminotransferase levels, HCV genotype distribution, and histologic changes were comparable among the three groups. The study indicates that most patients with chronic hepatitis C in Taiwan could be identified by current second-generation assay, and viremic but antibody seronegative patients were clinicopathologically similar to the seropositives. Most patients of the latter group could be diagnosed by a third-generation assay, indicating the usefulness of this assay.     

Hepatitis C virus antibodies, viral RNA and genotypes in sera from patients on maintenance haemodialysis

SUMMARY. Patients on maintenance haemodialysis in four dialysis centres were tested for markers of hepatitis C virus (HCV) infection. Antibody to HCV (anti-HCV) was detected by the second-generation enzyme immunoassay in 142 (26%) of the 543 patients and HCV RNA in 117 (22%) of whom four were without detectable anti-HCV in serum. Seventy-seven (66%) were infected with HCV of genotype II/1b, 31 (27%) with genotype III/2a and eight (7%) with genotype IV/2b. in a distribution similar to that in blood donors who carried HCV asymptomatically. Haemodialysis patients had high HCV RNA titres comparable to those of patients with chronic hepatitis C. HCV RNA was detected in 96 (26%) of the 365 patients with a history of transfusion more frequently than in 21 (12%) of the 178 without previous transfusion ( P <0.001). In transfused patients, frequencies of anti-HCV and HCV RNA increased in parallel with the duration of haemodialysis. The frequency of anti-HCV in non-transfused patients, however, did not change appreciably with the duration of haemodialysis up to 22 years. The patients with anti-HCV had a higher frequency of HCV RNA in serum than symptom-free blood donors with anti-HCV (113/142 or 80% vs 109/166 or 66% P <0.01) and the patients with HCV RNA had a lower frequency of elevated aminotransferase levels than blood donors with HCV RNA (5/113 or 4% vs 27/109 or 25%, P <0.00l). These results indicate that transfusion is a significant cause of HCV infection in patients on maintenance haemodialysis, and that these patients are prone to establish the HCV carrier state after infection.     

Ethnic differences in the prevalence of anti-hepatitis C antibodies and hepatitis B surface antigen in Israeli blood donors by age, sex, country of birth and origin

Summary. The presence of anti-hepatitis C virus (HCV) antibodies frequently indicates both persistent infection and infectivity. Consequently, blood donors found to be anti-HCV positive, are excluded from the donor pool. The aim of this study was to compare age, sex and ethnic differences in the prevalence of anti-HCV antibodies with that of hepatitis B surface antigen (HBsAg) among immigrant and Israeli-born blood donors. Anti-HCV antibodies were assayed by a second-generation enzyme-immunoassay (EIA) and HBsAg by a standard EIA in a sample of 136 977 blood donors in Israel during 1992. The overall age-adjusted prevalence of anti-HCV antibodies was 0.66% in men and 0.55% in women, and for HBsAg, 0.85% and 0.44%, respectively. There was a significant increase in the prevalence of anti-HCV antibody with age, and significant differences by country of birth, with the highest prevalence found among those born in the former USSR and eastern Europe. This contrasted with the findings for the prevalence of HBsAg, where the highest rates were among those born in northern Africa. Among Israeli-born donors, differences in the prevalence of anti-HCV antibodies by parental country of origin were minimal and much less than for HBsAg. Hence the prevalence of anti-HCV antibodies in Israel is strongly associated with age and country of birth but not with country of origin. There is little evidence of substantial vertical or intra familial transmission of HCV infection in Israel.     

Clinical significance of hepatitis C virus (HCV) infection in liver transplant recipients

Hepatitis C virus (HCV) infection was studied in 60 liver transplant recipients. Antibodies to HCV were tested by both a second-generation ELISA test and a four-recombinant immunoblot assay (4-RIBA) just before the transplant and every three months thereafter. HCV RNA detection was performed by polymerase chain reaction (PCR) at least three times after the transplant in all the patients. Thirty-nine patients tested negative by ELISA before LT (group A), 14 patients tested positive by both serological tests (group B), and seven tested positive only by ELISA (group C). Posttransplant hepatitis was diagnosed in 11/14 in group B in comparison with 3/39 in group A (P<0.001) and 1/7 in group C (P<0.05). HCV RNA was detected in the sera of 14/14 patients in group B but in only 1/7 in group C and 6/39 in group A. Only 2/15 patients developed posttransplant hepatitis in the absence of HCV RNA detection. These data suggest that HCV is the major cause of hepatitis after LT. Patients HCV seropositive by RIBA test before the transplant formed a group of high-risk patients for developing viremia and hepatitis afterwards.Part of this work was presented at the XIVth International Congress of the Transplantation Society. Paris. August 1992.This work was supported by a grant from Fondo de Investigaciones Sanitarias de la Seguridad Social (FISS 92/0357).     

Serotyping of hepatitis C virus in chronic type C hepatitis in Taiwan: Correlation with genotypes

To evaluate the usefulness of a new serologic assay to group hepatitis C virus (HCV), genotypes identified by this serotyping method were compared to those identified by a polymerase chain reaction (PCR) assay with type-specific primers in 71 Taiwanese patients with chronic type C hepatitis. The group-specific antibodies against different HCV genotypes were detected by using an enzyme-linked immunosorbent assay (ELISA) based on group-specific recombinant peptides (C14-1 and C14-2) within the NS4 region. Among 71 patients positive for current second-generation HCV antibodies, HCV RNA was detected in 55 patients by PCR with primers from the 5′ untranslating region, and in 52 by genotype-specific PCR. In 49 (89%) of 55 viremic patients, the results of serotyping by ELISA showed complete agreement with those determined by PCR genotyping, and none of the patients showed a group opposite to that of HCV genotype. The positive rate of group-specific antibodies (69/71;97%) was even better than that of the PCR (55/71;78%). We conclude that this new serotyping assay is highly sensitive and specific for the determination of HCV genotypes, and will be useful in future epidemiologic studies, as well for clinical application.     

Hepatitis C virus serum markers and liver disease in children with leukemia during and after chemotherapy

The pattern of hepatitis C virus (HCV) serum markers and liver disease was investigated in 11 leukemic children showing anti-HCV reactivity at least once during long-term observation to define the role of HCV infection and the behavior of HCV serologic markers in this patient cohort. Antibodies to HCV by first- and second-generation enzyme-linked immunosorbent assay (ELISA) and by second-generation (four antigens) recombinant immunoblotting assay (RIBA) and HCV-RNA by nested polymerase chain reaction (PCR) were serially examined in serum. Liver disease was defined according to transaminase levels. Seven of 11 patients were found HCV-RNA positive during chemotherapy and after blood transfusion, 3 of 11 became viremic during follow-up, and 1 of 11 was always HCV-RNA negative. Seroconversion to anti-HCV positivity by second-generation ELISA occurred in all the HCV-RNA positive children either during or after chemotherapy. Alanine aminotransferase (ALT) levels were elevated in all the HCV-RNA positive patients during antileukemic treatment and normalized in seven of them after therapy withdrawal, despite persisting viremia. These results indicate that HCV- RNA testing by polymerase chain reaction is required to correctly identify HCV infection in patients with leukemia while on chemotherapy. Viremia did not correlate with ALT levels and anti-HCV patterns.     

Evaluation of branched DNA signal amplification for the detection of hepatitis C virus RNA

Summary. There is an increasing need for a practical assay to measure HCV RNA to assess the viral burden in chronic hepatitis C virus (HCV) infection as viral load relates to transmission and therapeutic response. This study evaluates branched DNA (bDNA) signal amplification, a technique that avoids many of the pitfalls of polymerase chain reaction (PCR). The bDNA assay uses a microtitre well format and a series of capture, target and amplification probes that bind RNA to the well and then successively bind oligonucleotides to the RNA and branched DNA molecules to the oligonucleotides. Enzyme-labelled probes are bound to the arms of the bDNA and light output from a chemiluminescent substrate is directly proportional to the amount of starting HCV RNA. Appropriate standards provide direct quantitation. Whereas PCR amplifies the HCV genome, bDNA amplifies the hybridization signal. In testing a standardized, coded panel, bDNA showed 100% specificity and detected five of six sera proven to transmit hepatitis C to the chimpanzee; PCR detected all six infectious sera. Serial samples were measured in two acute and five chronic cases of transfusion-associated hepatitis and in three commercial seroconversion panels. In acute cases, 10⁷–10⁸ molecular equivalents per ml (eq per ml) of HCV RNA were detected prior to peak alanine aminotransferase (ALT) activity and then rapidly declined to non-detectable levels. Similar levels of HCV RNA were observed early in the course of two patients who progressed to chronic hepatitis; the chronic course was characterized by diminished, fluctuating and sometimes non-detectable levels of HCV RNA. In two chronic cases, HCV RNA was not detected, or only transiently detected by bDNA, but was present when assayed by PCR. In one chronic case, the periodicity of HCV RNA levels closely paralleled the fluctuations of ALT suggesting a relationship between viral replication and subsequent hepatocellular injury. In testing 50 blood donors whose anti-HCV reactivity was confirmed by a recombinant immunoblot assay (RIBA), HCV RNA was detected by bDNA in 41 (81%), while PCR was positive in 45 (90%); the overall concordance between bDNA and PCR in 100 anti-HCV enzyme immunoassays (EIA) reactive donor samples was 96%. Lastly, bDNA showed the loss of HCV RNA in six out of six evaluable patients who had complete biochemical responses to interferon; five out of six non-responders also showed appreciable declines in HCV RNA level, but in only two did HCV RNA drop below the detection limit; these two cases remained PCR positive. Seventeen placebo-treated patients did not lose HCV RNA by either bDNA or PCR. Hence the bDNA assay is a practical means to measure HCV RNA in a variety of clinical settings. Although it is not as sensitive as PCR, it has greater specificity, is directly quantitative, and can be used in any routine laboratory that can perform microwell EIAs. This simplified quantitation may be of particular benefit in evaluating the probability of HCV transmission and the response to anti-viral therapy.