A novel antigen detection immunoassay for field diagnosis of hepatitis C virus infection

The limitations of dominant methods-based on the detection of anti-HCV antibodies or HCV viremia currently used for the diagnosis of HCV infection enhance efforts to have a rapid, simple, sensitive, and specific alternative diagnostic approach to detect viral antigens. A highly reactive IgG antibody was raised to HCV-NS4 recombinant antigen. The produced antibody showed no cross-reactivity with the other HCV structural and nonstructural recombinant antigens (C1 + 2, C3 + 4, E2/NS1, NS3, NS5). The well established ELISA technique was adapted to detect the new target HCV-NS4 antigen in serum samples. Extremely high agreement was found between the results of ELISA and qualitative detection of HCV-RNA, using a RT-PCR test as a gold standard for the diagnosis of HCV infection. Based on these encouraging results, a novel enzyme immunoassay; dot-ELISA was developed for rapid (approximately 5 min) and simple qualitative detection of the target HCV antigen in serum. The developed method detected the HCV target antigen in 95% of serum samples from HCV infected individuals, with a specificity of 97% using sera of noninfected individuals in comparison with PCR test. The antigen detection method showed high predictive values of positive (99%) and negative (90%). Moreover, the dot-ELISA could detect the HCV target antigen in sera negative for anti-HCV Abs, but positive for HCV-RNA, and in sera of HCV infected individuals with low viremia, as well as those with high viremia, using quantitative RT-PCR. Accordingly, the developed highly sensitive and specific HCV antigen detection method could be applied for mass screening of HCV infection.

[Patients with HBV, HCV and HIV antigens--medical management, surgical procedures, equipment sterilization principles]

The purpose of the study was to present information about clinical treatment of HIV, HBV and HCV infection seropositive patients. We present indications and principles for hospitalization, conventional and surgical treatment and sterilization methods.

[Frequency of asymptomatic C viral infections in children referred to hospital treatment for various reasons]

In 2221 children aged 0.468-17.580 (56% boys and 44% girls) referred to hospital treatment for various reasons, antibodies anti HCV were determined with 3rd Generation Axsym (Abbott) test. In 3% (66/221) children the result was positive. Significant increase in the frequency of anti HCV occurrence was observed in children over 6, especially in 9, 10 and 11 years old--54% (36/66). Children anti HCV positive came mainly from large cities: 83% (55/66). Risk factors are presumed to be firstly blood sampling in out-patient clinics 34.8% (23/66) and hospitalization 22.7% (15/66), then dental procedures 18.2 (12/66), hairdressing and cosmetic procedures (tattoo and ear pricking) 12.1% (8/66). The authors point at the necessity of control in institutions performing such procedures as well as the need of sanitary education among medical personnel and school children in the period of hepatotropic viral infections.

Comparison of serum hepatitis C virus RNA and core antigen concentrations and determination of whether levels are associated with liver histology or affected by specimen storage time

An enzyme immunoassay has recently been developed for the hepatitis C virus (HCV) core antigen. To evaluate the possible association between core antigen and HCV RNA levels with regards to the change in liver histology over time as well as study the effect of duration of storage on viral load results, sequential sera were analyzed from 45 patients with chronic HCV infection who had undergone two or more liver biopsies. A relatively strong association was found between the core antigen and HCV RNA concentrations (r(s) = 0.8), with a core antigen level of 1 pg/ml corresponding to approximately 1,000 IU/ml. All 42 sera with detectable HCV RNA at the time of the second biopsy had core antigen concentrations above 1 pg/ml, and the three sera without detectable HCV RNA had concentrations below 1 pg/ml. No association was found between HCV RNA or core antigen levels and the stage of fibrosis in biopsy samples, progression of fibrosis, necro-inflammatory grade, steatosis, genotype, alanine aminotransferase level, or alcohol consumption. A significant association was demonstrated between the storage time of the samples and both the HCV RNA and core antigen concentrations. The median log HCV RNA concentrations (international units/milliliter) were 3.92 for the sera obtained at the time of the first biopsy (median storage time, 13.0 years) and 4.41 for the sera obtained at the time of the second biopsy (median storage time, 6.6 years) compared to 5.96, the median for 102 different routine clinical patient samples.

CD4 T lymphocyte proliferative responses to hepatitis C virus (HCV) antigens in patients coinfected with HCV and human immunodeficiency virus who responded to anti-HCV treatment

CD4 T lymphocyte proliferative responses to hepatitis C virus (HCV) antigens were evaluated before and during an anti-HCV regimen (interferon-alpha2a and ribavirin) in 36 patients coinfected with HCV and human immunodeficiency virus (HIV), to determine whether immune responses against HCV antigens are present in such patients, whether these responses are modified by anti-HCV treatment, and whether they are correlated with treatment efficacy. The CD4 responses against HCV antigens (primarily core antigens) detected at study entry in one-half of the patients did not correlate with anti-HCV treatment efficacy. Of 36 patients, 8 had patterns of persistent immune response to infection by genotypes 3 or 4 that were significantly correlated with sustained virologic response. Persistent immunologic reactivity and sustained virologic response coexisted only in patients infected with genotype 3. These findings suggest that HCV genotype may influence specific immune response, which, in turn, is implicated in virologic control.

Serum hepatitis C virus and hepatitis B surface antigenaemia in Nigerian patients with acute icteric hepatitis

Acute hepatitis is common in Nigeria and hepatitis B virus (HBV) infection has been a major aetiological factor. However, the role of Hepatitis C Virus (HCV) infection is yet undetermined. Forty-five consecutive Nigerian patients with Acute Icteric hepatitis (AIH) attending the Medical Clinic of the University College Hospital, Ibadan, Nigeria and 45 healthy adult Nigerians (controls) were studied for evidence of infection with both viruses. Questionnaire on risk procedures which predispose to acquisition of both HBV and HCV infections were administered to the patients. Blood samples were collected from all the subjects and tested for antibody to HCV (Anti-HCV) and Hepatitis B surface Antigen (HBsAg) using the second generation Enzyme Linked Immunoassay (Monolisa -R, Sansofi, Pasteur; France). Anti-HCV was detected in 21(47%) and 17(38%) of the patients and controls respectively. The corresponding prevalences of HBsAg were 38(84%) and 11(24%), p < 0.001. Hepatitis B virus infection was found to occur more than HCV infection in the patients with AIH but similar among the controls. Combined HBV and HCV infection occurred more frequently among the patients (42.1%) than in the control (11%) (; < 0.001). Although there was no significant difference in the HCV infection between the two groups, isolated HCV infection is commoner in the control than in the patients with AIH, (p < 0.001). Similarly, single HCV infection is commoner than lone HBV infection among the control, p < 0.05. In summary, this study shows that while both HBV and HCV infections are common in Nigeria, AIH may be more associated with HBV than HCV in the country.

Detection of hepatitis C core antigen in serum or plasma as a marker of hepatitis C viraemia in the serological window-phase

A new immunoassay for the detection of hepatitis C core antigen (HCVcoreAg) in peripheral blood during serological window-phase was evaluated among healthy blood donors, commercially available hepatitis C virus (HCV) seroconversion panels and in-house specimens from individuals undergoing seroconversion. Among 1964 low-risk blood donor samples, seven samples were initially reactive but only one was repeat reactive. Reactivity of this specimen was not confirmable by neutralization with specific anti-HCV core antibody, and the sample was negative for HCV RNA by polymerase chain reaction (PCR). The specificity of the HCVcoreAg enzyme-linked immunosorbent assay (ELISA) was 99.95%. In seven commercially available HCV seroconversion panels, HCVcoreAg appeared 23-46 days earlier than anti-HCV antibody by third generation assay. Additional testing with specimens from patients undergoing anti-HCV seroconversion indicated that HCVcoreAg becomes undetectable by the present test format soon after the onset of antibody. This test may be considered as an alternative to nucleic amplification techniques (NAT) for blood donor HCV screening. Additional development of technology for detecting HCVcoreAg may be useful for patient diagnosis and therapy monitoring.

[Localization of hepatitis C virus core protein in the nucleus of peripheral blood mononuclear cells of hepatitis C patients]

BACKGROUND

To study the significance of the expression of HCV core protein in PBMC of patients with chronic hepatitis C and to evaluate the relationship between HCV core protein expression and clinical states.

METHODS

Identification of HCV protein antigen (Ag) in PBMC of 66 hepatitis C patients by immunohistochemical method and clinical status of the patients with HCV protein positive expression were investigated. In 27 out off 66 patients the HCV RNA and HCV Ag in PBMC were detected with RT-PCR and immunohistochemical method.

RESULTS

The HCV Ag (core+NS3) was identified in PBMC in 51 out of 66 patients (77.27%). It was also demonstrated that HCV core protein in nucleus showed strong expression and NS3 protein in cytoplasm showed weak expression. The expression of core protein in nucleus of PBMC were 35.29% in advanced chronic hepatitis patients, which was significantly higher than that from moderate cases (5.88%).

CONCLUSIONS

This study suggested that the expression of PMBC-HCV core protein may be related to the clinical state of the patients. The nuclear expression of HCV core protein in PBMC of patients with hepatitis C may be related to the persistence and activity of the chronic hepatitis C virus and play an important role in the pathogenesis of cirrhrosis and hepatocellular carcinoma.

Correlation of histology, viral load, and in situ viral detection in hepatic biopsies from patients with liver transplants secondary to hepatitis C infection

The diagnosis of hepatitis C infection in the setting of liver transplantation in based on several variables, including histopathologic changes and the presence of viral RNA in the serum. It may be difficult to differentiate acute rejection from recurrent viral hepatitis in liver biopsies from patients who received liver transplants for end-stage hepatitis C infection. The purpose of this study was to analyzed the histologic features, viral load, and in situ viral detection in 37 biopsies taken from 25 people who underwent liver transplant for end-stage hepatitis C infection. Hepatitis C antigen was detected in 9 of 37 (24%) biopsies using immunohistochemistry; the detection rate increased to 19 of 37 (51%) using reverse transcriptase in situ polymerase chain reaction for viral cDNA. Hepatitis E cDNA was detected in 4 of 37 (11%) cases, hepatitis G cDNA in 3 of 37 (8%) cases and in 1 case cytomegalovirus was noted; with several cases of dual infection, 22 of 37 (59%) of tissues were positive for at least 1 virus. Histologic parameters that significantly correlated with in situ viral detection included single-cell hepatocyte necrosis (P = 0.02), bile duct damage (P = 0.03), lymphoid aggregates (P = 0.02), and cholestasis (P = 0.01). Further, a serum viral load exceeding 1,250,000 viral equivalents/ml was strongly correlated with in situ viral detection in the liver (P = 0.01). We conclude that certain histologic features and an increased viral load are highly correlated with the in situ detection of viral RNA in the liver, which is consistent with recurrent viral infection.

Detection of HCV core antigen in human serum and plasma with an automated chemiluminescent immunoassay

BACKGROUND

Currently, the detection of HCV infection in blood donors relies on the ability of immunoassays to detect circulating HCV antibodies. However, a significant delay exists between the time of infection and the development of antibodies. This delay (window period) can last up to 70 days. The introduction of NAT for the detection of HCV RNA has reduced this window period dramatically. However, NAT is labor intensive, prone to contamination, and expensive as compared with standard serologic tests.

STUDY DESIGN AND METHODS

An automated, microparticle-based chemiluminescent assay for the detection of HCV core antigen in human serum and plasma was developed. The specificity and sensitivity of this prototype assay were evaluated by testing a population of normal blood donors and commercially available seroconversion panels.

RESULTS

The HCV core antigen assay exhibited a 99.9-percent specificity by detecting a single repeatably reactive sample out of 1004 normal donors tested. Assay sensitivity was determined by comparing the HCV core antigen detection rate with the antibody seroconversion profile and the rate of HCV RNA detection. Among 15 seroconversion panels examined, core antigen was detected in 69 of 70 antibody-negative and/or RNA-positive samples for a sensitivity relative to NAT of 98.6 percent.

CONCLUSION

These data indicate that the automated, microparticle-based chemiluminescent HCV core antigen assay can reduce the window period for detection of potentially infected blood donors by 32.7 days, and it represents a viable alternative to HCV RNA testing.

Incident hepatitis C virus infection in a community-based population in Japan

Hepatitis C virus (HCV) is an important cause of liver disease throughout the world. However, the natural history and pathogenesis of this infection is still not completely understood. The aim of this study was to characterize the evolution of incident, asymptomatic HCV infection in a community-based population in Japan. The Miyazaki Cohort Study is a prospective study of adult residents in two villages, one of which has a very high prevalence of HCV. Nine hundred and seventy-three people from this village were enrolled in the cohort between 1984 and 1995, with antibodies to HCV (anti-HCV) found in 23%. During subsequent visits to annual health screens, new HCV seroconverters were identified among susceptible individuals, and their sequential samples were tested for anti-HCV, HCV-RNA, and HCV core antigen. Fourteen participants (six males, eight females) acquired anti-HCV during the first 11 years of study follow-up, at an incidence rate of 362 per 100 000 person-years. Detectable HCV-RNA and high anti-HCV titres (> 1:2048) were observed for more than 5 years following seroconversion in 80% (8/10) of seroconverters with sufficient information, indicating the development of persistent infection in these subjects. Three (37.5%) of the eight sero converters with persistent infection had fairly consistent, albeit mild, alanine aminotransferase elevations (30-130 IU/L) during the study. Anti-HCV seroconversions occurred at a very high rate in this community-based population in Japan, in which this infection is endemic. Persistence also developed at a high frequency among the cases of newly acquired infection, although the associated liver enzyme abnormalities were mild.

[Study on hepatitis C virus infection of peripheral blood mononuclear cells in chronic hepatitis C patients]

OBJECTIVE

To demonstrate HCV infection and replication in the peripheral blood mononuclear cells (PBMCs) of hepatitis patients by the methods of molecular biology, immunology and electron microscopy.

METHODS

HCV RNA and antigens were detected in the PBMCs of 28 patients with chronic hepatitis C by RT-PCR, Immunohistochemistry and electron microscopy, respectively.

RESULTS

The positive rate of HCV RNA and HCV antigens were 77.27% (17/22) and 75.00% (21/28), respectively. Two types of spherical HCV-like particles with diameter of approximately 65 nm and 110 nm were observed in cytoplasmic vesicles by electron microscopy in the PBMCs with high titer of HCV RNA and antigens in 10 patients. The budding and shedding of these particles could also be found in the cytoplasmic vesicles. Immunoelectron microscopy using antibodies against HCV core and NS(3) demonstrated that the particles contained HCV antigens.

CONCLUSION

HCV can infect and replicate in the PBMCs of patients with chronic hepatitis C.

Hepatitis C virus core mutations reduce the sensitivity of a fluorescence enzyme immunoassay

Four of 107 samples obtained from hepatitis C virus (HCV) carriers showed lower HCV core antigen levels in a fluorescence enzyme immunoassay (FEIA) than expected from corresponding HCV RNA levels. Nucleotide sequencing revealed a mutation in the HCV core region (Thr49Pro) that appears to have reduced the FEIA sensitivity.

Beta-lipoproteins influence the serum level of hepatitis C virus

Low density lipoprotein receptor (LDLR) has been proposed as a candidate receptor for hepatitis C virus (HCV). According to previous reports, free beta-lipoproteins in a human serum may regulate the rate of hepatocyte infection by competing with the virus. Therefore, serum HCV levels should be regulated by the rise and fall of serum beta-lipoproteins since the infection rate of virions influences HCV replication in hepatocytes and release of virions by hepatocytes. In this study, we examined the relationship between serum beta-lipoproteins and HCV-antigen (Ag) levels in patients with chronic type C hepatitis. Patients were selected based on strict criteria to eliminate other factors that might influence serum HCV levels. Serum concentrations of beta-lipoproteins and HCV-Ag were measured two or more times within 3 months for each patient. The result showed that HCV-Ag levels were negatively correlated with the increased beta-lipoproteins. The results support the concept that LDLR is a HCV receptor and that beta-lipoproteins competitively inhibit the infection of hepatocytes with HCV through the LDLR.

Detection of hepatitis C core antigen in the antibody negative 'window' phase of hepatitis C infection

BACKGROUND AND OBJECTIVES

Despite improvements in assays for anti-HCV, there remains a significant delay before the appearance of antibodies following infection, during which, circulating viral RNA is present. We have evaluated a prototype assay for the serological detection of hepatitis C virus (HCV) core antigen with specimens derived from the early phase of HCV infection.

MATERIALS AND METHODS

Serial specimens from 24 individuals undergoing HCV seroconversion were tested for the presence of anti-HCV, HCV RNA and HCV core antigen.

RESULTS

HCV antigen was detected at the same time as HCV RNA in 83% (20/24) cases. The mean time to the first detection of HCV antigen was approximately 1 day later than HCV RNA. Overall, 87% of HCV-RNA-positive specimens contained detectable HCV core antigen.

CONCLUSION

These results indicate that HCV core antigen can be identified by routine serological ELISA in specimens from the early antibody-negative phase of HCV infection. A test for HCV core antigen may be a useful test for identifying window phase blood donations from antibody negative donors infected with HCV.

Evaluation of a new enzyme immunoassay for hepatitis C virus (HCV) core antigen with clinical sensitivity approximating that of genomic amplification of HCV RNA

The aim of this study was to analyze the clinical performance of a new enzyme immunoassay (EIA) for hepatitis C virus (HCV) core antigen in comparison with the reverse transcription polymerase chain reaction (RT-PCR). A total of 310 patients with acute or chronic hepatitis C, and 132 HCV-negative controls were studied. Chemiluminescence EIA with monoclonal anti-HCV core antigen was used, and qualitative and quantitative commercial RT-PCRs and an in-house nested RT-PCR were performed. Compared with nested RT-PCR, the core antigen assay showed 97% sensitivity and 100% specificity in 75 patients with chronic hepatitis C and 132 controls. HCV core antigen was positive in 16 (94%) of 17 patients with acute hepatitis C at initial consultation. In 3 persons prospectively followed, core antigen was detected in the first available (1-3 weeks) post-transfusion sample. In 167 anti-HCV-positive individuals, 129 (77%) were viremic; core antigen was detected in 126 (98%) compared with 129 (100%) for nested RT-PCR and 121 (94%) for the commercial RT-PCR. In 48 patients with chronic hepatitis C treated with interferon alfa, the concentration of core antigen before treatment was significantly (P <.002) lower in patients with sustained response than in nonresponders. All responders had a sustained loss of core antigen, whereas all nonresponders remained core antigen positive. The concentrations of HCV core antigen and HCV RNA correlated significantly (n = 48, r =.627, P <.001). In conclusion, the HCV core antigen assay is useful for the diagnosis of acute and chronic hepatitis C, and for predicting and monitoring the effect of interferon alfa treatment.

HLA class II genotypes associated with chronic hepatitis C virus infection and response to alpha-interferon treatment in Poland

AIMS/BACKGROUND

Recent evidence suggests that spontaneous clearance of hepatitis C virus (HCV) may be associated with the HLA DQB1*0301 allele but there is still some debate over the role of other alleles and HLA haplotypes in HCV infection. As this may best be resolved by studying genetically different populations, we have investigated HLA class II-encoded susceptibility and resistance to HCV infection in a relatively sedentary population of patients from northwestern Poland.

METHODS

The distributions of HLA class II DRB1, DQA1, DQB1 and DPB1 alleles were determined by standard PCR-protocol in 129 unrelated patients with chronic hepatitis C (anti-HCV and HCV-RNA positive) and 103 healthy unrelated racially-matched control subjects. Fifty-five patients were treated with alpha-interferon (5 MIU thrice weekly for 6 months) out of whom 29 showed a complete response and 26 were non-responders.

RESULTS

A significantly reduced frequency of the DQB1*0301 allele in the patients was observed (24.0% vs. 38.8%; p=0.015). Additionally, two different DR-DQ haplotypes were found to be associated with chronic HCV infection: DRB1*1501-DQA1*01-DQB1*0602 (24.0% vs. 12.6%; p= 0.027) and DRB1*0701-DQA1*0201-DQB1*02 (31.8 vs. 12.6%; p=0.0006), the latter difference being most pronounced in those patients who responded to alpha-interferon treatment (41.4% vs. 12.6%; p=0.00048).

CONCLUSIONS

The results confirm the negative association between chronic HCV and DQB1*0301 and identify two novel genetic associations. In particular, the DRB1*0701-DQA1*0201-DQB1*02 haplotype is associated with both chronic infection and response to alpha-interferon. Interestingly, the same haplotype is reportedly associated with non-response to hepatitis B vaccination.

Relationship between histological prognosis of chronic hepatitis C and amount of hepatitis C virus core protein in serum

BACKGROUND

Hepatitis C virus (HCV) viraemia is one of the factors for histological prognosis of chronic hepatitis C.

METHODS

One hundred and thirty-five patients who received hepatic biopsies twice at intervals of 5 years or longer were followed up for a mean of 9.7 +/- 4.0 years were studied retrospectively. The amount of HCV viraemia present was measured as the concentration of HCV core protein by using the fluorescence enzyme immunoassay method.

RESULTS

Multiple-regression analysis, using deterioration of the histological stage as a dependent variable, showed that greater age (P = 0.041), higher stage of hepatic histology at the start of follow up (P = 0.029), and higher serum concentration of core protein (P < 0.001) were independent factors affecting the deterioration of the liver's histological stage. At follow up, no significant difference in histological stage was seen between patients with serum HCV core protein > or = 100 pg/mL (n = 60) and those with serum core protein < 100 pg/mL (n = 75). The histological grade in patients with high serum core-protein levels tended to be significantly worse and the deterioration rate of the histological stage was significantly higher than in those with low HCV core protein levels (68 vs 35%, P < 0.001). The mutation rate of the HCV envelope-2/non-structural 1 (E2/NS1) nucleotide region was compared in two patients who had high serum concentrations of HCV core protein and whose histological stage had deteriorated with two patients who had low serum concentrations of the core protein and whose histological stages remained unchanged. No significant difference in E2/NS1 mutation was found.

CONCLUSIONS

The amount of HCV viraemia was suggested to be a significant factor for determining histological outcome in patients with chronic hepatitis C. The mutation rate in the E2/NS1 region did not seem to be associated with the prognosis of chronic hepatitis C.

[Hepatitis C virus antibodies in 34130 blood donors in Tunisian Sahel]

Since January 6th 1994 to december 31 1997. We researched hepatitis C Virus antibodies by second and third generation ELISA in 34,130 bloods donors living in "Sahel Tunisien". 193 were positive (0.56%). Only 171 of them were secondary tested by immunoblot assay (anticore, anti NS5, anti NS3, anti NS4). Which was positive in 53 cases (30.9%); in determined (presence of only one antibody) in 78 cases (45.6%) and negative, in 40 cases (23.3%). There was a significant relation between a ratio over than 2.5 in ELISA and immunoblot positivity. Immune response to different hepatitis virus antigens were heterogeneous with predominant in determined profile. (78/171 cases). Most of donors of the last profile had either anti NS5 (32/78) or anti NS3 (33/78) and we excluded them even through usually negative in P.C.R and associated with a very low risk of contamination.

NAT: perspectives for cellular components

The introduction of routine testing to detect viral genomes in donated blood was originally driven by requirements for plasma fractionation in relation to exclusion of hepatitis C virus (HCV) RNA. Nevertheless, it was obvious from the outset that a dual standard for fractionated products and individual blood components would be untenable. In many countries therefore, planning for introduction of nucleic acid testing (NAT) of blood incorporated progression to release of HCV RNA tested components. HCV was singled out because of its long seronegative 'window period', relatively high prevalence and incidence in blood donors, rapid burst time and high genome copy number during seroconversion. The latter properties made HCV particularly suitable for detection in pools of samples. If HCV RNA testing is required for release of labile components such as platelets, rapid provision of NAT results is vital because of short shelf life of platelets and the problems of delays when resolving the infectious unit in a reactive pool. For NAT release of labile components smaller sample pool sizes allow faster resolution of RNA positive units. Smaller pools involve high test throughput, the likely need for more testing laboratories and ensuing increased costs. Single sample testing is the ultimate extrapolation of reducing sample pool size. With reduced pool sizes or single sample testing, the option of testing for other viruses (e.g. HIV or HBV) singly or in multiplex also arises. The cost-benefit and incremental yield of such strategies in the light of 'combo' assays for HIV Ag/Ab and the recently described HCV Ag assay will require careful and objective assessment, together with re-appraisal of anti-HBc screening for detection of HBV infected donors at the "tail-end" of carriage.