De novo HCV infection among dialysis patients: a prospective study by HCV core antigen ELISA assay

BACKGROUND

Dialysis patients remain a high-risk group for hepatitis C virus infection. The current diagnosis of hepatitis C virus in dialysis patients includes serological measurement of anti-hepatitis C virus antibody; however, nucleic acid amplification technology for assessing hepatitis C virus viraemia is commonly used in other populations. An enzyme-linked immunosorbent assay test for detecting antibody to hepatitis C nucleocapsid core antigen (hepatitis C virus core antigen) in human serum has been recently developed (hepatitis C virus Core Antigen enzyme-linked immunosorbent assay test). It is conceived for screening of donor blood products to significantly reduce the 'serologic window' occurring before seroconversion during acute hepatitis C virus.

AIM AND METHODS

A cohort (n = 72) of patients on maintenance haemodialysis in a single unit in the years 2000-2003 was included. Study patients were tested monthly by hepatitis C virus Core Antigen enzyme-linked immunosorbent assay in a prospective, clinical trial. Routine results obtained by hepatitis C virus Core Antigen enzyme-linked immunosorbent assay test were confirmed by assessing hepatitis C virus viraemia by branched-chain DNA (bDNA) signal amplification assay.

RESULTS

De novo hepatitis C virus infection was identified in three patients during the study period; the hepatitis C virus incidence was 1.38% (95% confidence intervals, 1.31-4.09) per year. In each patient, hepatitis C virus core antigen testing allowed the serological identification of acute hepatitis C virus before anti-hepatitis C virus seroconversion. Hepatitis C virus RNA testing confirmed the results obtained by hepatitis C virus Core Antigen enzyme-linked immunosorbent assay in all cases. The time from initial hepatitis C virus detection by hepatitis C virus Core Antigen Assay and anti-hepatitis C virus seroconversion was not greater than four weeks. Two (67%) of three patients with de novo hepatitis C virus acquisition were HBsAg negative; both these patients underwent an initial phase of hepatitis C virus viraemia that was associated with an increase in alanine aminotransferase activity and preceded the seroconversion to anti-hepatitis C virus antibody. Nosocomial transmission of hepatitis C virus between haemodialysis patients was implicated in at least two (67%) of these three patients.

CONCLUSIONS

Serological testing for hepatitis C virus core antigen can identify acute hepatitis C virus infection before anti-hepatitis C virus seroconversion. The time from initial hepatitis C virus detection by hepatitis C virus core antigen assay and anti-hepatitis C virus seroconversion was not >4 weeks. De novo acquisition of hepatitis C virus in haemodialysis was associated with a rise in alanine aminotransferase levels. Hepatitis C virus core antigen enzyme-linked immunosorbent assay test results can be obtained in routine laboratories without the need of special equipment or training. Hepatitis C virus core antigen testing among anti-hepatitis C virus negative patients on maintenance dialysis is suggested in order to early assess de novo hepatitis C virus within dialysis units.

Evaluation of a membrane filter assay system, Ortho HCV Ab Quick Pack, for detection of anti-hepatitis C virus antibody

A simple membrane immunoassay assay system, Quik Pack, for the detection of hepatitis C virus antibody was compared with two enzyme-linked immunosorbent assays (ELISAs) in a study of 600 serum samples. Quik Pack exhibited excellent sensitivity and specificity: 96.0 and 99.7%, respectively, versus the ELISA-2 and 99.7 and 99.4%, respectively, versus the ELISA-3.

Serologic responses to hepatitis C virus in solid organ transplant recipients

BACKGROUND

Hepatitis C (HCV) infection is known to have been transmitted by both blood transfusion and donor organs. We sought to determine the historical incidence of donor- and transfusion-acquired HCV infection in kidney transplant (RTx) and heart transplant (HTx) recipients at our center and to study the kinetics of seroconversion to HCV.

METHODS

A bank of sera collected from organ donors (388 RTx and 88 HTx) who received allografts between January 1984 and April 1992 was screened for anti-HCV using a third generation enzyme immunoassay. Recipient sera collected before transplant (preTx), at 1 year after transplant, and at last follow-up were tested. Fresh follow-up sera on all surviving anti-HCV-positive (+) RTx and HTx, all anti-HCV-negative (-) HTx, and a subset of 85 anti-HCV- RTx were assayed for HCV RNA using an reverse transcriptase-polymerase chain reaction assay.

RESULTS

Twenty-four of 388 RTx (6.2%) and 2 of 88 HTx (2.3%) were anti-HCV+ preTx. Eight of 218 (3.7%) organ donors were anti-HCV+. Six of the seven (85.7%) anti-HCV+ donors with adequate recipient follow-up transmitted HCV infection to one or more recipients. Nineteen of 313 RTx (6.1%) and 8 of 72 HTx (11.1%) with follow-up > or =1 year seroconverted to anti-HCV. One of 85 (1.2%) anti-HCV- RTx and 3 of 44 (6.8%) anti-HCV-HTx were HCV RNA+ when tested at last follow-up. Five cases of de novo HCV infection occurred after the introduction of first generation anti-HCV screening of donors. Persistent viremia (HCV RNA+) at last follow-up was observed in 70.6% (12/17) RTx anti-HCV+ preTx. Fourteen of 15 (93.3%) RTx and 9 of 9 (100%) HTx with de novo HCV infection had persistent viremia. Seroconversion was more delayed in HTx than RTx (P=0.0572, log-rank Mantel-Cox statistic) although both groups demonstrated an impaired humoral response to HCV when compared with the immunocompetent host.

CONCLUSIONS

Organ donor- and transfusion-acquired HCV infection was common in RTx and HTx transplanted before the introduction of second generation anti-HCV screening in 1992. Serologic responses to HCV are often delayed and sometimes absent in these patients. Assays for HCV RNA should be considered as a screening test for the detection of HCV infection in this population. Serologic responses to HCV were more impaired in HTx compared with RTx, which may reflect the more intensive immunosuppressive regimens given to HTx at our center.

Cost-effectiveness of screening blood donors for hepatitis C and non-A, non-B, non-C hepatitis. The EATHIS Eco Research Group. European Acute Transfusion Hepatitis Interferon Study

The current approach to screening for hepatitis C and non-A, non-B, non-C hepatitis in French blood transfusion centers involves a combination of a transaminase assay and tests for antibodies to hepatitis B core antigen (anti-HBc) and antibodies to hepatitis C virus (anti-HCV). A decision-analysis model was used to assess the cost-effectiveness ratio of this approach compared to the former approach, which included only transaminase and anti-HBc screening. Cost data were collected by a questionnaire sent to 26 centers throughout France. The average costs of diagnostic kits, equipment, staff, and administration were calculated. Estimates of prevalence and sensitivity values came from the medical literature. The cost-effectiveness ratio was expressed in French francs per infected donor detected. A sensitivity analysis of the variables in the model was performed to estimate the validity of the cost-effectiveness ratio. For 100,000 donations the incremental cost of the current approach reached FrF 2,566,111 (about US $500,000), with a marginal effectiveness of 180 donations detected. The sensitivity analysis showed the effect of prevalence on the incremental cost-effectiveness ratio. Transfusion centers may change their screening approach in areas of high or low prevalence of hepatitis C in France.

Early detection of anti-HCc antibody in acute hepatitis C virus (HCV) by western blot (immunoblot) using a recombinant HCV core protein fragment

Crude extract from Escherichia coli which expressed a recombinant protein containing amino acids 2 to 127 of the hepatitis C virus (HCV) core protein was used to detect the antibody against HCV core protein (anti-HCc). After electrophoretic separation of proteins from the extract, Western blot (immunoblot) analysis was performed with the serum samples. This method was compared with a commercially available second-generation enzyme immunoassay (EIA) which employed synthetic peptides corresponding to highly antigenic segments of both structural and nonstructural portions of HCV. Also, reverse transcription PCR for HCV RNA was used for comparison. Seventy-two serum samples from three groups of patients were tested. Groups I and II represented healthy subjects and subjects with acute hepatitis A or B, respectively. Group III included patients with newly acquired acute hepatitis C. By Western blot analysis, 31 of 31 (100%) samples from group I were negative for anti-HCc antibody, whereas 4 of 22 (18%) samples from group II were positive for anti-HCc. One of these four samples was also positive for anti-HCV antibody by the second-generation EIA (1 of 22 [4.5%]). Among 19 patients diagnosed with newly acquired acute hepatitis C, 4 (21%) were positive for anti-HCV by the second-generation EIA, whereas 12 of 19 (63%) were positive for anti-HCc by Western blot analysis. Of EIA-positive subjects, 4 of 4 (100%) were also positive for anti-HCc by Western blot analysis, whereas among EIA-negative subjects, 8 of 15 (53%) were positive. For HCV RNA detected by reverse transcription PCR, 15 of 19 (80%) of this group of samples were positive. Strikingly, the peak bilirubin level for patients with EIA-negative and Western blot-positive results is significantly higher than that for patients with consistent EIA and Western blot results (22.7 versus 7.2 mg/dl). A series of serum samples from a patient with concurrent hepatitis B and C viral infection was also studied by both tests. Although anti-HCc persisted throughout the course of infection, anti-HCV by EIA converted from negative to positive 20 days after admission and then converted back to negative 30 days later.

Geographical distribution of hepatitis C virus genotypes in blood donors: an international collaborative survey

The frequency of infection with the six classified major genotypes of hepatitis C virus (HCV) was investigated in 447 infected volunteer blood donors from the following nine countries: Scotland, Finland, The Netherlands, Hungary, Australia, Egypt, Japan, Hong Kong, and Taiwan. Viral sequences in plasma from blood donors infected with HCV were amplified in the 5'-noncoding region and were typed by restriction fragment length polymorphism analysis. Electrophoresis of DNA fragments produced by cleavage with HaeIII-RsaI and ScrFI-HinfI allowed HCV types 1 (or 5), 2, 3, 4, and 6 to be identified. Further analysis with MvaI-HinfI allowed sequences of the type 5 genotype to be distinguished from sequences of the type 1 genotype. Types 1, 2, and 3 accounted for almost all infections in donors from Scotland, Finland, The Netherlands, and Australia. Types 2 and 3 were not found in the eastern European country (Hungary), where all but one of the donors were infected with type 1. Donors from Japan and Taiwan were infected only with type 1 or 2, while types 1, 2, and 6 were found in those from Hong Kong. HCV infection among Egyptians was almost always by type 4. Donors infected with HCV type 1 showed broad serological reactivity with all four antigens of the second generation Chiron RIBA-2 assay (Chiron Corporation, Emeryville, Calif.), while infection with divergent HCV genotypes elicited antibodies mainly reactive to c22-3 and c33c. Reactivities with antibodies 5-1-1 and c100-3 were infrequent and were generally weak, irrespective of the geographical origin of the donor. Because the envelope region of HCV is even more variable than the NS-4 region, it is likely that vaccines based on these proteins need to be multivalent and perhaps specifically adapted for different geographical regions.

Confirmation of hepatitis C virus antibody in blood donors

Of 103,203 donations collected in Scotland and Northern Ireland over a 3-month period and screened for HCV antibody by Ortho or Abbott second-generation ELISAs, 340 were found repeatedly reactive. Supplementary testing with RIBA-2 resulted in 77 being classified as positive, 130 as indeterminate, and 133 as negative. PCR analysis of the positives and indeterminates indicated viraemia in 65 (84%) of the positives and 7 (5.5%) of the indeterminates. To determine if PCR analysis could be eliminated or reduced by further serological testing, all RIBA-2 positives and indeterminates were tested by UBI and Wellcozyme ELISAs and Innolia and RIBA-3 immunoblots. All RIBA-2 positives with bands to more than 1 gene product were detected in all 4 systems, but > 60% of RIBA-2 indeterminates were negative in those tests that contain either recombinant antigens or synthetic peptides derived independently from those used by Ortho/Abbott tests. A comparison of data from the 79 reactive with the core (c22) region revealed only 16 samples reactive in all 4 systems as well as Ortho and Abbott. These 16 included all 6 of the PCR positives in the 79 c22 indeterminate samples. ELISAs and immunoblots using independently derived antigens can offer a useful method of screening out nonspecific reactions in Ortho or Abbott ELISAs, hence reducing the need for PCR testing. Some caution is required as all such tests do not contain identical mixes of antigenic material.

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)

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.

Storage conditions of blood samples and primer selection affect the yield of cDNA polymerase chain reaction products of hepatitis C virus

We have noticed that suboptimal specimen processing and storage conditions may cause false-negative results in the detection of hepatitis C virus (HCV) RNA in plasma or serum. To establish the influence of specimen handling in a serological laboratory on the rate of detection of HCV RNA by the cDNA polymerase chain reaction (cDNA-PCR), we tested routine serum samples and fresh-frozen plasma samples from the same bleeding from confirmed anti-HCV-positive blood donors. When primers from the NS3/NS4 region were used, HCV RNA was detected in fresh-frozen plasma from 67% of the donors, whereas positive results were obtained with only 50% of the serum samples that had been subjected to routine serological procedures. Analysis of the same samples with primers from the highly conserved 5'-terminal region (5'-TR) revealed an HCV RNA detection rate of 92% for both the routine and the fresh-frozen samples. However, the yield of the amplification product in routine samples was strongly reduced compared with that in fresh-frozen plasma. Comparison of both primer sets for cDNA-PCR showed that the 5'-TR primer set was 10- to 100-fold more effective in detecting HCV RNA. We also analyzed the effect of storage of whole EDTA-blood and serum at room temperature and at 4 degrees C on the yield of the amplification product. A rapid decline in detectable HCV RNA of 3 to 4 log units was observed within 14 days when whole blood and serum were stored at room temperature. By contrast, no perceptible reduction in the cDNA-PCR signal was found in freshly prepared serum stored at 4 degrees C.