Hepatitis C virus (HCV)-specific T-cell responses among recombinant immunoblot assay-3-indeterminate blood donors: a confirmatory evidence of HCV exposure

HCV genotype 6 prevalence, spontaneous clearance and diversity among elderly members of the Li ethnic minority in Baisha County, China

The epidemiology of hepatitis C virus varies widely across geographical regions and ethnic groups. Our previous study showed that 6 strains isolated from Baisha County, Hainan Island, China, were all new genotype 6 (gt6) subtypes which differed significantly from subtypes of other regions. In the current study, we conducted a comprehensive epidemiological survey of HCV in the Li ethnic group, native to Baisha County. Anti-HCV antibodies were detected by 2 independent ELISAs in all participants, and positive results confirmed by the recombinant immunoblot assay (RIBA) and HCV RNA viral loads were measured. Univariate chi-square test and multivariable logistic regression analyses were used to determine the risk factors for HCV infection and spontaneous clearance rates. Indeterminate RIBA results were excluded or included in analyses; consequently, findings were expressed as a range. Direct sequencing of partial regions within NS5B and E1 was employed for genotyping. Among 1682 participants, 117 to 153 were anti-HCV positive (7.0%-9.1%), with 42.7%-52.6% confirmed to have cleared infection. Anti-HCV positivity was associated with older age (≥60 years) (OR = 0.02, 95% CI 0.01-0.05, P < 0.01) and surgery (OR = 2.75, 95% CI 1.36-5.57, P < 0.01), with no significant difference found between the HCV infection group and the HCV spontaneous clearance group. The gt6 subtype distribution characteristics of Baisha County were unique, complex and diverse. The sequences did not cluster with known gt6 subtypes but formed 4 Baisha community-specific groups. HCV infection in members of the Li minority ethnic group is characterized by high prevalence rates in the elderly, high spontaneous clearance rates and broad gt6 diversity.

Screening for hepatitis C in a general adult population in a low-prevalence area: the Tromsø study

Background

Chronic hepatitis C virus (HCV) infection can progress to cirrhosis and end-stage liver disease in a substantial proportion of patients. The infection is frequently asymptomatic, leaving many infected individuals unaware of the diagnosis until complications occur. This advocates the screening of healthy individuals. The aim of this study was to estimate the prevalence of HCV infection in the general adult population of the municipality of Tromsø, Norway, and to evaluate the efficiency of such an approach in a presumed low-prevalence area.

Methods

The study was part of the seventh survey of the Tromsø Study (Tromsø 7) in 2015–2016. Sera from 20,946 individuals aged 40 years and older were analysed for antibodies to HCV (anti-HCV). A positive anti-HCV test was followed up with a new blood test for HCV RNA, and the result of any previous laboratory HCV data were recorded. Samples positive for anti-HCV and negative for HCV RNA were tested with a recombinant immunoblot assay. All HCV RNA positive individuals were offered clinical evaluation.

Results

Among 20,946 participants, HCV RNA was detected in 33 (0.2%; 95% CI: 0.1–0.3), of whom 13 (39.4%; 95% CI: 22.7–56.1) were unaware of their infection. The anti-HCV test was confirmed positive in 134 individuals (0.6%; 95% CI: 0.5–0.7) with the highest prevalence in the age group 50–59 years. Current or treatment-recovered chronic HCV-infection was found in 85 individuals (0.4%; 95% CI: 0.3–0.5) and was associated with an unfavorable psychosocial profile.

Conclusion

In this population-based study, the prevalence of viraemic HCV infection was 0.2%. A substantial proportion (39%) of persons with viraemic disease was not aware of their infectious status, which suggests that the current screening strategy of individuals with high risk of infection may be an inadequate approach to identify chronic HCV infection hidden in the general population.

Anti-HCV immunoblot indeterminate results in blood donors: non-specific reactivity or past exposure to HCV?

BACKGROUND AND OBJECTIVE

The significance of anti-HCV immunoblot (IB) indeterminate results can be difficult to determine. We analysed results for blood donors tested on the MP Diagnostics HCV Blot 3.0 IB assay to determine whether indeterminate results representing past exposure to HCV could be distinguished from those due to non-specific reactivity.

MATERIALS AND METHODS

Results for all donors tested by IB during the study period (July 2010 to December 2013) were included in this study.

RESULTS

Of 131 donors tested by IB, 34 (26.0%) were negative, 38 (29.0%) were indeterminate, and 59 (45.0%) were positive. There was no significant difference in IB band reactivity strength between indeterminate and positive donors. The PRISM HCV chemiluminescent immunoassay (ChLIA) sample to cut-off (s/co) ratio distribution for the indeterminate donors was significantly higher than for those with biological false reactivity (P = 0·037), but significantly lower than for donors who were IB positive/HCV RNA negative (P < 0·001) or IB not tested/HCV RNA positive (P < 0·001). Of donors available for follow-up, 53.1% of the indeterminate group disclosed a putative risk factor for HCV infection compared to 39.4% (P < 0·001) for the IB-negative group, 76.6% (P = 0·065) for the IB-positive group and 83.4% (P < 0·001) for the HCV RNA-positive group.

CONCLUSION

The results of this study indicate that PRISM ChLIA s/co ratios >2·00 with IB indeterminate results predict exposure to HCV, particularly in the presence of putative risk factors for HCV infection. These findings may be applied to optimizing counselling of donors with indeterminate HCV results.

Future complications of chronic hepatitis C in a low-risk area: projections from the hepatitis c study in Northern Norway

BACKGROUND

Hepatitis C (HCV) infection causes an asymptomatic chronic hepatitis in most affected individuals, which often remains undetected until cirrhosis and cirrhosis-related complications occur. Screening of high-risk subjects in Northern Norway has revealed a relatively low prevalence in the general population (0.24%). Despite this, late complications of HCV infection are increasing. Our object was to estimate the future prevalence and complications of chronic HCV infection in the period 2013-2050 in a low-risk area.

METHODS

We have entered available data into a prognostic Markov model to project future complications to HCV infection.

RESULTS

The model extrapolates the prevalence in the present cohort of HCV-infected individuals, and assumes a stable low incidence in the projection period. We predict an almost three-fold increase in the incidence of cirrhosis (68 per 100,000), of decompensated cirrhosis (21 per 100,000) and of hepatocellular carcinoma (4 per 100,000) by 2050, as well as a six-fold increase in the cumulated number of deaths from HCV-related liver disease (170 per 100,000 inhabitants). All estimates are made assuming an unchanged treatment coverage of approximately 15%. The estimated numbers can be reduced by approximately 50% for cirrhosis, and by approximately one third for the other endpoints if treatment coverage is raised to 50%.

CONCLUSION

These projections from a low-prevalence area indicate a substantial rise in HCV-related morbidity and mortality in the coming years. The global HCV epidemic is of great concern and increased treatment coverage is necessary to reduce the burden of the disease.

A cross-sectional study of hepatitis C among people living with HIV in Cambodia: Prevalence, risk factors, and potential for targeted screening

The epidemiology of hepatitis C in Cambodia is not well-known. We evaluated the prevalence of hepatitis C virus (HCV) and risk factors in the HIV cohort of Sihanouk Hospital Center of Hope in Phnom Penh to strengthen the evidence for suitable HCV testing strategies among people living with HIV (PLWH) in Cambodia. All consenting adult PLWH without a history of HCV treatment were tested for HCV between November 2014 and May 2016 according to the CDC algorithm (HCV antibody II electro-chemiluminescence immunoassay, followed by COBAS® AmpliPrep/COBAS® TaqMan® HCV PCR and INNO-LIA® HCV Score immunoblot end-testing). Genotyping was performed using the line probe assay Versant HCV genotype 2.0®. The study enrolled a total of 3045 patients (43% males, median age: 42.5 years, <1% high-risk). HCV antibodies were detected in 230 (7.6%; 95% confidence interval [CI] 6.6-8.5). Upon further testing, HCV antibodies were confirmed in 157 (5.2%; 95% CI 4.4-6.0) and active HCV in 106 (3.5%; 95% CI 2.8-4.2). Viremic prevalence peaked among men aged 50-55 years (7.3%) and women aged >55 years (11.2%). Genotype 1b (45%) and 6 (41%) were predominant. Coinfected patients had a higher aspartate-to-platelet ratio index, lower platelets, a lower HBsAg positivity rate and more frequent diabetes. Based on logistic regression, blood transfusion antecedents (adjusted odds ratio 2.9; 95% CI 1.7-4.9), unsafe medical injections (2.0; 1.3-3.2), and partner (3.4; 1.5-7.6) or household member (2.4; 1.3-3.2) with liver disease were independently associated with HCV in women. However, having a tattoo/scarification (1.9; 1.1-3.4) and household member (3.1; 1.3-7.3) with liver disease were associated with HCV in men. Thus, our study found intermediate endemicity of active hepatitis C in a large Cambodian HIV cohort and provides initial arguments for targeted HCV screening (>50 years, partner/household member with liver disease, diabetes, increased aspartate-to-platelet ratio index) as efficient way forward.

Characterization of differential antibody production against hepatitis C virus in different HCV infection status

BACKGROUND

The Centers for Disease Control and Prevention (CDC) issued an update on hepatitis C virus (HCV) testing approach, in which it omitted the use of recombinant immunoblot assay (RIBA) in the diagnostic algorithm and recommended that future studies are needed to evaluate the performance of HCV testing without RIBA. As Egypt has the highest prevalence of HCV worldwide, we aimed to evaluate the value of RIBA in HCV testing in a high prevalence population. Our objective was to clarify whether enzyme linked immunosorbent assay (ELISA) anti-HCV signal-to-cutoff (S/CO) ratios were able to discriminate true positive from false positive anti-HCV antibody status and to evaluate the role of RIBA in solving this problem which may lead to a redefined strategy for diagnosis of HCV infection. Our second objective was to elucidate the effects of different HCV peptides of both structural and non-structural proteins on the humoral immune response to HCV infection.

METHODS

The current study drew results from 167 individuals divided into three groups: Group I: included 77 HCV antibody positive (ELISA) high risk health care workers (HCW), Group II: included 56 presumably uninfected individuals who showed normal liver enzymes, negative HCV RNA and were asymptomatic. Their ELISA HCV antibody S/C ratio ranged from 0.9 to <5. Group III: included 34 patients enrolled from outpatient clinics of Ain Shams Hospital with persistent viral replication, elevated liver enzymes, and chronic HCV related liver disease. All study participants were assessed for the presence of anti-HCV antibodies by 3(rd) generation ELISA which was confirmed by RIBA.

RESULTS

Interpreting the results of both ELISA and RIBA together, false positive results were highly significantly increased in HCW when compared with the other two groups. Indeterminate and false negative results were only found in the presumably uninfected group. For differentiated antibody responses by RIBA, chronic HCV cases had the highest frequency of positive antibody response to core peptides while the presumably uninfected group had the lowest. Antibody response to E2 was found less frequently in chronic cases than Core 1, Core 2 and NS3. The specific antibody response to the different HCV peptides showed the same distribution of frequencies in both chronic HCV cases and the presumably uninfected individuals with the chronic cases having the highest frequencies. This distribution was different from the HCW. The most evident difference was the reaction towards NS3 which was the highest antibody producing peptide in chronic HCV and presumably uninfected individuals whereas in HCW Core1 was the highest.

CONCLUSION

The HCV antibody immunoblot assay (RIBA) is still necessary for the detection of false positive cases which can occur quite frequently in countries of high prevalence as Egypt. Indeterminate RIBA results indicate a waning antibody response in elderly individuals who recovered from previous or distant HCV infection.

Multicenter clinical evaluation of the new 3rd generation assay for detection of antibodies against hepatitis C virus on the VIDAS(®) system

BACKGROUND

Detection of antibodies (anti-HCV) against hepatitis C virus (HCV) is indispensable for screening and diagnosis of viral hepatitis and for the viral safety of blood, tissue or organ donations. It gains additional importance by the new HCV drugs which improve the therapeutic possibilities dramatically.

OBJECTIVE

To evaluate the performance of a newly developed immune assay for anti-HCV based on the well-established VIDAS platform.

STUDY DESIGN

The assay was evaluated with samples from anti-HCV negative blood donors and from patients with or without HCV markers in six centres in France, Spain and Egypt. The status of the samples was determined by using CE-marked immune assays (Architect, AxSym, Prism, Vitros), two immunoblots (RIBA, Inno-Lia) and/or HCV RNA results.

RESULTS

Specificity was 99.67% in 10,320 French blood donors without anti-HCV, 99.5% in 200 anti-HCV negative hospitalized European patients and 99.0% in 198 negative patients from Egypt. Sensitivity was 99.7% in 1054 patients pretested positive by other assays; 345 patients with known genotype had genotype 1-6; 61 patients were co-infected with HIV. VIDAS was reactive in 78% of 91 patients with uncertain or very weak anti-HCV. It became on average positive at day 37 with seroconversion panels.

CONCLUSIONS

This multicentric, international study with >12,000 samples show that the new VIDAS anti-HCV assay is very suitable for screening and confirmation of HCV infection. Sensitivity, specificity and recognition of seroconversion compare favorably with well-established CE-marked tests and help to clarify discrepant results obtained with other assays.

T- and B-cell responses and previous exposure to hepatitis B virus in 'anti-HBc alone' patients

A serologic response to hepatitis B virus (HBV) defined as 'anti-HBc alone' is commonly observed, but its significance remains unclear. This study aimed to define the relationship between 'anti-HBc alone' serostatus and HBV infection, including HBV-specific T- and B-cell memory responses. We enrolled 31 'anti-HBc alone' patients. Total HBV DNA and cccDNA were tested by nested polymerase chain reaction (PCR) analysis in liver samples from 22 'anti-HBc alone' patients vs controls (chronic or resolved HBV infection), followed by HBsAg/HBcAg immunohistochemical (IHC) staining. IFN-γ secretion by HBV-specific T cells was compared in individuals who were 'anti-HBc alone' (n = 27), resolved HBV (n = 21), chronic HBV (n = 24) and 12 healthy controls using enzyme-linked immunospot (ELISpot) assays. An HBsAg-IgG B-cell ELISpot assay was performed in 'anti-HBc alone' patients before and after one dose of recombinant HBsAg vaccine. The majority (23/31, 74.2%) of the 'anti-HBc alone' individuals were co-infected with HCV. Infrequent intrahepatic total HBV DNA (2/22, 9.1%) and cccDNA (1/22, 4.5%) were detected in biopsies; HBsAg and HBcAg IHC staining was negative. HBV-specific T-cell responses were similar between 'anti-HBc alone' individuals and HBV resolvers. Circulating HBV-memory B-cell responses were detected in all 'anti-HBc alone' individuals, consistent with an HBsAg-specific memory pool. After one HBV vaccine dose, increased anti-HBs antibody levels were observed, accompanied by an expansion of HBsAg-specific memory B cells (P = 0.0226). 'Anti-HBc alone' individuals showed HBV-specific T-cell and memory B-cell responses typical of previous viral exposure and protective memory, suggesting a resolved infection.

Improving the safety of blood transfusion by using a combination of two screening assays for hepatitis C virus

BACKGROUND AND OBJECTIVES

To illustrate that the combination of a single nucleic acid amplification test (NAT) with a single immunoassay for hepatitis C virus (HCV) detection, as proposed internationally, may lead to the omission of anti-HCV reactive sera with non-reactive NAT results.

MATERIALS AND METHODS

In total, 822 of 519, 299 serum samples from 11 blood centres in China were retested for anti-HCV by using 10 screening assays to detect HCV antibodies. A recombinant immunoblot assay (RIBA HCV 3·0; Ortho-Clinical Diagnostics) was performed to define confirmed HCV infection status. Samples with positive or indeterminate RIBA-HCV results were tested by quantitative tests for HCV RNA (Roche Diagnostics).

RESULTS

We found that 47 of the 822 (5·72%) serum samples were RIBA-positive without detectable HCV RNA. For these samples, the 10 anti-HCV immunoassays gave discordant and unsatisfactory results (detection rate ranging from 10·64 to 34·04%; ratio per 100 000 donations ranging from 5·97 to 8·09). Compared with a single anti-HCV screening assay, the two-assay combination increased the detection of these samples. The five best combinations [Sorin and Lizhu enzyme immunoassays (EIAs), Ortho and Lizhu EIAs, Sorin and Wantai EIAs, Sorin EIA and Roche CIA and Ortho and Wantai EIAs] increased the detection rate from 46·81 to 55·57%, thus reducing the ratio per 100 000 donations of HCV-seropositive samples.

CONCLUSION

The combination of two anti-HCV screening immunoassays in parallel with an HCV NAT is a better strategy for HCV detection in blood centres to improve the safety of blood transfusion.

Indeterminate RIBA results were associated with the absence of hepatitis C virus RNA (HCV-RNA) in blood donors

INTRODUCTION

Hepatitis C virus (HCV) infection is diagnosed by the presence of antibodies and is supplemented by confirmatory testing methods, such as recombinant immunoblot assay (RIBA) and HCV-RNA detection. This study aimed to evaluate the efficacy of RIBA testing to diagnose HCV infection in blood donors positive for anti-HCV antibodies.

METHODS

A total of 102 subjects positive for anti-HCV determined by enzyme-linked immunosorbent assay (ELISA) at the Hematology and Hemotherapy Foundation of Bahia (HEMOBA) were later assessed with new samples using the Abbott Architect anti-HCV test (Abbott Diagnostics, Wiesbaden, Germany), the RIBA III test (Chiron RIBA HCV 3.0 SIA, Chiron Corp., Emeryville, CA, USA), the polymerase chain reaction (PCR; COBAS® AMPLICOR HCV Roche Diagnostics Corp., Indianapolis, IN, USA) and line probe assay (LiPA - Siemens, Tarrytown, NY, USA) genotyping for HCV diagnosis.

RESULTS

Of these new samples, 38.2% (39/102) were positive, 57.8% (59/102) were negative and 3.9% (4/102) were indeterminate for anti-HCV; HCV-RNA was detected in 22.5% (23/102) of the samples. RIBA results were positive in 58.1% (25/43), negative in 9.3% (4/43) and indeterminate in 32.6% (14/43) of the samples. The prevailing genotypes were 1 (78.3%, 18/23), 3 (17.4%, 4/23) and 2 (4.3%, 1/23). All 14 samples with indeterminate RIBA results had undetectable viral loads (detection limit ≤50 IU/mL). Of these samples, 71.4% (10/14) were reevaluated six months later. Eighty percent (8/10) of these samples remained indeterminate by RIBA, and 20% (2/10) were negative.

CONCLUSIONS

In this study, individuals with indeterminate RIBA results had no detectable HCV-RNA.

Two distinct functional patterns of hepatitis C Virus (HCV)-specific T cell responses in seronegative, aviremic patients

In hepatitis C Virus (HCV) high-risk groups, HCV-specific T cell responses have been detected in seronegative, aviremic persons who have no evidence of HCV infection. Herein, we investigated functional profiles of HCV-specific T-cell responses in seronegative, aviremic patients of a HCV high-risk group. Seventy seven hemodialysis patients with chronic renal disease were analyzed by IFN-γ ELISpot assays, and eight of 71 (11.3%) seronegative, aviremic patients displayed HCV-specific T-cell responses. Their HCV-specific memory T cells were characterized by assessing cytokine polyfunctionality, known to provide antiviral protection. By intracellular staining of IFN-γ, TNF-α, IL-2 and MIP-1β, we identified two distinct populations in the seronegative, aviremic patients: polyfunctional responders and TNF-α-predominant responders. In further analysis, occult HCV infection was excluded as a cause of the HCV-specific T cell response via secondary nested RT-PCR of HCV RNA in peripheral blood mononuclear cell samples. HCV-specific T cells targeted multiple epitopes including non-structural proteins in a single patient, implying that their T cells might have been primed by HCV proteins synthesized within the host. We conclude that HCV-specific memory T cells of seronegative, aviremic patients arise from authentic HCV replication in the host, but not from current occult HCV infection. By functional pattern of HCV-specific T cells, there are two distinct populations in these patients: polyfunctional responders and TNF-α-predominant responders.

Hepatitis C virus-specific cell-mediated immune responses in children born to mothers infected with hepatitis C virus

OBJECTIVE

To investigate the association between hepatitis C virus (HCV)-specific cell-mediated immunity (CMI) responses and viral clearance in children born to mothers infected with HCV.

STUDY DESIGN

A cross-sectional study of children from a mother-infant cohort in Egypt were enrolled to detect CMI responses to recombinant core and nonstructural HCV antigens (nonstructural segments NS3, NS4a/b, and NS5 of the HCV genome) using an interferon-gamma enzyme-linked immunospot assay. Children born to mothers with chronic HCV were enrolled into 3 groups: transiently viremic (n = 5), aviremic (n = 36), and positive control (n = 6), which consisted of 1 child with chronic HCV from this cohort and another 5 children with chronic HCV from a companion study. Children without HCV born to mothers without HCV (n = 27) served as a negative control group. Wilcoxon rank sum test was used to compare the magnitude of CMI responses between groups.

RESULTS

None of the 6 control children who were positive for HCV responded to any HCV antigen, and 4 (80%) of 5 children with transient viremia responded to at least one HCV antigen, compared with 5 (14%) of 36 and 3 (11%) of 27 children in the aviremic and negative control groups, respectively. Children with transient viremia elicited stronger responses than did negative controls (P = .005), positive controls (P = .011), or children without HCV viremia (P = .012), particularly to nonstructural antigens.

CONCLUSIONS

HCV-specific CMI responses were significantly higher in magnitude and frequency among transiently infected children compared with those persistently infected. This suggests CMI responses may be associated with past viral clearance and can identify children at high risk of infection, who can be targeted for health education, screening, and follow-up.

IL28B genetic variation and hepatitis C virus-specific CD4(+) T-cell responses in anti-HCV-positive blood donors

Epidemiological, viral and host factors are associated with the outcome of hepatitis C virus (HCV) infection, and strong host immune responses against HCV favour viral clearance. Recently, genome-wide association studies have shown a strong correlation between single-nucleotide polymorphisms (SNPs) near the interleukin-28B (IL28B) gene and spontaneous or treatment-induced HCV clearance. We have investigated whether protective IL28B genetic variants are associated with HCV-specific T-cell responses among Spanish blood donors. The rs12979860 IL28B haplotype was determined in 69 anti-HCV-positive blood donors (21 HCV RNA negative and 48 HCV RNA positive) and 30 seronegative donors. In all cases, HCV-specific CD4(+) T-cell responses to HCV recombinant proteins (core, NS3 and NS3 helicase) were assessed by ex vivo interferon-γ ELISpot assay. The rs12979860-CC genotype was highly overrepresented in donors with spontaneous HCV clearance when compared to those with chronic infection (76.2%vs 29.2%, P < 0.001; odds ratio, 7.77; 95% confidence interval, 2.4-25.3, P < 0.001). HCV-specific CD4(+) T-cell responses were detected in 16 (76.2%) spontaneous resolvers especially towards nonstructural proteins, but with no correlation with IL28B genotype. Chronic individuals had a significantly lower overall T-cell response again irrespective of IL28B genotype. When spontaneous resolvers and chronic individuals were stratified according to their IL28B genotype, significantly stronger T-cell responses were only observed among those with non-CC haplotypes. Although the protective rs12979860 IL28B CC genotype is associated with spontaneous HCV clearance, stronger CD4(+) T-cell responses towards NS3 were only evident among those with non-CC haplotypes.

T cell responses and viral variability in blood donation candidates with occult hepatitis B infection

BACKGROUND & AIMS

Occult HBV infection (OBI) is defined by the presence of HBV DNA in the liver and/or serum and negative HBsAg testing. Since the implementation of highly sensitive HBV DNA screening, OBI is also detected in healthy blood donors. The aims of this study were to investigate HBV-specific immune responses and genetic variability in donors with OBI, established by HBV DNA in serum.

METHODS

HBV-specific T-cell responses to HBV antigens were tested in 34 OBI donors by IFN-γ ELISpot, cytometric bead array, and intracellular cytokine staining. As comparison populations, 36 inactive HBV carriers, 22 donors with spontaneously resolved HBV infection, 24 vaccinated donors, and 25 seronegative donors were also included. Surface, pre-S, and pre-c/core genes from 44 genotype D isolates (24 OBI and 20 HBsAg-positive) were sequenced.

RESULTS

The immune response of OBI donors to the 3 HBV antigens was 29-41%, similar to the response in subjects with resolved HBV infection and higher than that in HBsAg-positive subjects. On sequence analysis, OBI donors presented a higher HBsAg mutation rate than HBsAg-positive subjects. Mutations were clustered in the major hydrophilic region of HBsAg, and no stop codons or relevant mutations that could affect antigen formation or detection were observed.

CONCLUSIONS

Our results suggest that immune response can suppress viral replication to low levels and HBsAg expression to undetectable levels in OBI blood donors. Relevant mutations were not found in the genomic HBsAg coding region. Hence, the fact that HBsAg was not detected in OBI is likely due to low HBsAg production, rather than to a failure of laboratory reagents.

Reversal of nonstructural protein 3-specific CD4(+) T cell dysfunction in patients with persistent hepatitis C virus infection

Hepatitis C virus (HCV)-specific T cell responses are essential for HCV control, and chronic infection is characterized by functionally altered antigen-specific T cells. It has been proposed that the early inactivation of specific CD4(+) T cell responses may be involved in establishment of HCV persistence. We have investigated whether HCV-specific CD4(+) T cells dysfunction can be reversed in vitro. Nonstructural protein 3 (NS3) and core-specific CD4(+) T cells from eight chronically infected and eight spontaneously resolved HCV individuals were selected through transient CD154 (CD40 ligand) expression, and their functional profile (IFN-γ, IL-2, TNF-α, IL-10 and IL-4 production by enzyme-linked immunospot assay, cytometric bead array and intracellular cytokine staining, and proliferation by carboxy-fluorescein diacetate succinimidyl ester dilution assay) was determined both ex vivo and after in vitro expansion of sorted CD154-expressing cells in the absence of specific antigen in IL-7/IL-15-supplemented medium. Ex vivo bulk CD4(+) T cells from chronic patients expressed CD154 in most cases, albeit at lower frequencies than those of resolved patients (0.11%vs 0.41%; P = 0.01), when stimulated with NS3, but not core, although they had a markedly impaired capacity to produce IL-2 and IFN-γ. Antigen-free in vitro expansion of NS3-specific CD154(+) cells from chronic patients restored IFN-γ and IL-2 production and proliferation to levels similar to those of patients with spontaneously resolved infection. Hence, NS3-specific CD4(+) T cell response can be rescued in most chronic HCV patients by in vitro expansion in the absence of HCV-specific antigen. These results might provide a rationale for adoptive immunotherapy.

The clinical relevance of persistent recombinant immunoblot assay-indeterminate reactions: insights into the natural history of hepatitis C virus infection and implications for donor counseling

BACKGROUND

Recombinant immunoblot assay (RIBA) is used to determine the specificity of antibody to hepatitis C virus (anti-HCV). The RIBA result is recorded as positive, negative, or indeterminate. The interpretation and significance of RIBA-indeterminate reactions are unclear. We addressed the clinical relevance of these reactions in the context of the natural history of HCV infection in a prospectively followed cohort of anti-HCV-positive blood donors.

STUDY DESIGN AND METHODS

Donor demographics, exposure history, and humoral and cell-mediated immunity (CMI) were compared in 15 RIBA-indeterminate subjects, nine chronic HCV carriers, and eight spontaneously recovered subjects. Serum samples were tested for anti-HCV by a quantitative, liquid luciferase immunoprecipitation system (LIPS). CMI was assessed by interferon-γ enzyme-linked immunosorbent spot assay.

RESULTS

In the LIPS assay, the sum of antibody responses to six HCV antigens showed significant (p < 0.001) stepwise diminution progressing from chronic carriers to spontaneously recovered to RIBA-indeterminate subjects. CMI responses in RIBA-indeterminate subjects were similar to spontaneously recovered subjects and greater than chronic carriers and controls (p < 0.008). A parenteral risk factor was identified in only 13% of RIBA-indeterminate subjects compared to 89% of chronic carriers and 87% of spontaneously recovered subjects. RIBA-indeterminate donors were older than the other groups.

CONCLUSION

The CMI and LIPS results suggest that persistent RIBA-indeterminate reactions represent waning anti-HCV responses in persons who have recovered from a remote HCV infection. In such cases, detectable antibody may ultimately disappear leaving no residual serologic evidence of prior HCV infection, as reported in a minority of long-term HCV-recovered subjects.

Declining hepatitis C virus (HCV) prevalence in pregnant women: impact of anti-HCV screening of donated blood

BACKGROUND

Screening blood donors for hepatitis C virus (HCV) antibody has effectively mitigated transfusion transmission of HCV. We conducted a post hoc analysis to clarify the impact of donor screening on a general population of reproductive-age females and their offspring.

STUDY DESIGN AND METHODS

Anti-HCV screening in Japan started in late-1989. In a cohort studied between May 1990 and November 2004, a total of 22,664 consecutive serum samples from pregnant women were screened for anti-HCV. Reactive samples were further tested for HCV RNA. Linear structural regression was applied to identify causal relationships.

RESULTS

Anti-HCV-reactive rates declined significantly by two measures. First, among women known to have been transfused, rates fell from 14.8% to 3.1% with the implementation of anti-HCV screening (p < 0.01). Nevertheless, this is 10 times higher than the 0.3% reactive rate seen in a similar cohort of nontransfused women. Second, rates fell from 1.8% among women born in 1955 or before to 0.3% for women born in 1966 or later (p < 0.01). Among 103 anti-HCV-reactive women, 31 (30%) had been transfused and another 17 (17%) had other identifiable risk factors. The remaining 55 (53%) had no clear risk factor. Blood transfusion accounted for 19% of anti-HCV acquisition, by path analysis. Only one infant in this cohort was vertically infected with HCV.

CONCLUSION

Anti-HCV screening of donated blood and hygienic improvements have markedly decreased HCV infection of pregnant women with a transfusion history; however, 70% of anti-HCV-reactive women were deemed to be infected via routes other than transfusion.