Immunocompromised children and young people are at no increased risk of severe COVID-19

OBJECTIVES

We aimed to prospectively describe the incidence and clinical spectrum of SARS-CoV-2 infection in immunocompromised paediatric patients in the UK.

METHODS

From March 2020 to 2021 weekly questionnaires were sent to immunocompromised paediatric patients or their parents. Information, including symptom presentation and SARS-CoV-2 PCR test results, was collected from 1527 participants from 46 hospitals. Cross-sectional serology was investigated in February and March 2021.

RESULTS

Until the end of September 2020, no cases were reported. From September 28th 2020 to March 2021 a total of 38 PCR-detected SARS-CoV-2 infections were reported. Of these, four children were admitted to hospital but none had acute severe COVID-19. Increasing age in association with immunodeficiency increased reporting of SARS-CoV-2 infection. Worsening of fever, cough, and sore throat were associated with participants reporting SARS-CoV-2 infection. Serology data included 452 unvaccinated participants. In those reporting prior positive SARS-CoV-2 PCR, there were detectable antibodies in 9 of 18 (50%). In those with no prior report of infection, antibodies were detected in 32 of 434 (7•4%).

CONCLUSIONS

This study shows SARS-CoV-2 infections have occurred in immunocompromised children and young people with no increased risk of severe disease. No children died.

Short-term changes observed in multiparametric liver MRI following therapy with direct-acting antivirals in chronic hepatitis C virus patients

Methods

We applied multiparametric MRI to assess changes in liver composition, perfusion and blood flow in 17 patients before direct-acting antiviral (DAA) therapy and after treatment completion (within 12 weeks of last DAA tablet swallowed).

Results

We observed changes in hepatic composition indicated by a reduction in both liver longitudinal relaxation time (T1, 35 ± 4 ms), transverse relaxation time (T2, 2.5 ± 0.8 ms; T2* 3.0 ± 0.7 ms), and liver perfusion (28.1 ± 19.7 ml/100 g/min) which we suggest are linked to reduced pro-inflammatory milieu, including interstitial oedema, within the liver. No changes were observed in liver or spleen blood flow, splenic perfusion, or superior mesenteric artery blood flow.

Conclusion

For the first time, our study has shown that treatment of HCV with DAAs in patients with cirrhosis leads to an acute reduction in liver T1, T2 and T2* and an increase in liver perfusion measured using MR parameters. The ability of MRI to characterise changes in the angio-architecture of patients with cirrhosis after intervention in the short term will enhance our understanding of the natural history of regression of liver disease and potentially influence clinical decision algorithms.

Key Points

• DAAs have revolutionised the treatment of hepatitis C and achieve sustained virological response in over 95% of patients, even with liver cirrhosis.

• Currently available non-invasive measures of liver fibrosis are not accurate after HCV treatment with DAAs, this prospective single-centre study has shown that MRI can sensitively measure changes within the liver, which could reflect the reduction in inflammation with viral clearance.

• The ability of MRI to characterise changes in structural and haemodynamic MRI measures in the liver after intervention will enhance our understanding of the progression/regression of liver disease and could potentially influence clinical decision algorithms.

Host genetic factors associated with hepatocellular carcinoma in patients with hepatitis C virus infection: A systematic review

Hepatitis C virus (HCV)-infected patients are at risk of developing hepatocellular carcinoma (HCC). Individuals at heightened risk could be targeted by intensive follow-up surveillance. We have conducted a systematic review of the literature to identify host genetic predisposition to HCC in HCV-infected patients. A comprehensive search of Medline and Embase databases was performed, and the strength of evidence of associations for each gene on development of HCC was evaluated. We identified 166 relevant studies, relating to 137 different genes, or combinations thereof. Seventeen genes were classified as having "good" evidence of an association, a significant association was observed for 37 genes but this finding had not yet been replicated, 56 genes had mixed or limited evidence of an association, and 27 genes showed no association. IFNL3/4, TNF-α and PNPLA3 genes had the most evidence of an association. There was, however, considerable heterogeneity in study design and data quality. In conclusion, we identified a number of genes with evidence of association with HCC, but also a need for more standardized approaches to address this clinically critical question. It is important to consider the underlying mechanism of these relationships and which are confounded by the presence of other HCC risk factors and response to therapy. We also identified many genes where the evidence of association is contradictory or requires replication, as well as a number where associations have been studied but no evidence found. These findings should help to direct future studies on host genetic predisposition to HCC in HCV-infected patients.

Current knowledge and future perspectives on acute hepatitis C infection

Acute hepatitis C virus (HCV) infections are frequently seen worldwide in certain risk groups, with an annual incidence rate varying between 0.08% and 66%. Although this incidence is substantial, a delayed diagnosis during chronic infection is most often made in the absence of clinical symptoms in the acute phase of the infection. Currently used methods to diagnose acute HCV infection are IgG antibody seroconversion and repeated HCV RNA measurements, although no definitive diagnostic test is currently available. Progress in the field of adaptive and innate immune responses has aided both advances in the field of HCV vaccine development and a more basic understanding of viral persistence. The rapid changes in the treatment of chronic HCV infection will affect therapeutic regimens for acute HCV infection in the coming years, leading to shorter treatment courses and pegylated interferon-free modalities. This review gives an overview of the current knowledge and uncertainties, together with some future perspectives on acute hepatitis C epidemiology, virology, immunology, and treatment.

Reasons for nonuse of antiviral treatment in patients with chronic hepatitis C infection and thrombocytopaenia: a retrospective chart review from five European countries

Antiviral therapy has been shown to reduce the risk of disease progression, liver damage and death in patients with chronic hepatitis C virus (HCV) infection. While interferon labels recommend that patients with platelet counts below 50 × 10(3) /μL not receive interferon-based therapy, it is unknown to what extent thrombocytopaenia influences treatment decisions in practice. This study profiles the reasons for withholding antiviral treatment in HCV patients with thrombocytopaenia in five European countries. Medical records of 466 patients who had HCV infection and thrombocytopaenia (platelet count <100 × 10(3) /μL) in 2006 were retrospectively reviewed for clinical characteristics. Collected data included use of antiviral therapy and reasons for withholding therapy. In total 184 of 466 patients (39.5%) did not receive interferon-based therapy during the study period, with treatment withheld most frequently due to multiple clinical characteristics including hepatic cirrhosis (16.3%), thrombocytopaenia (16.3%) and age >60 years (10.9%). The reasons for lack of treatment varied among countries, with thrombocytopaenia as a reason being more common in Italy (10.9%) and Spain (20.0%), and less common in France, Germany and the UK (3.2-7.1%). Overall, thrombocytopaenia was reported as the only reason for withholding treatment in 4.9% of untreated patients. This study demonstrates that thrombocytopaenia is one of many factors, indicative of the poor clinical state of the patient, that contributes to withholding antiviral treatment. In 4.9% of untreated patients, thrombocytopaenia can be considered as a modifiable factor to enable more HCV patients to receive guideline-recommended therapy and thus improved clinical outcomes.

The cost of treatment failure: resource use and costs incurred by hepatitis C virus genotype 1-infected patients who do or do not achieve sustained virological response to therapy

Chronic hepatitis C virus (HCV) infection places a considerable economic burden on health services. Cost-effectiveness analyses of antiviral treatment for patients with chronic HCV infection are dependent on assumptions about cost reductions following sustained virological response (SVR) to therapy. This study quantified the medium-term difference in health resource usage and costs depending on treatment outcome. Retrospective chart review of patients with HCV genotype 1 infection who had received at least 2 months pegylated interferon and ribavirin therapy, with known treatment outcome was conducted. Disease status was categorized as chronic hepatitis, cirrhosis or decompensated liver disease. Health resource use was documented for each patient in each disease state. Unit costs were from the NHS 'Payment by Results' database and the British National Formulary. One hundred and ninety three patients (108 SVR, 85 non-SVR) with mean follow-up of 3.5 (SVR) and 4.9 (non-SVR) years were enrolled. No SVR patient progressed to a more severe liver disease state. Annual transition rates for non-SVR patients were 7.4% (chronic hepatitis to cirrhosis) and 4.9% (cirrhosis to decompensated liver disease). By extrapolation of modelled data over a 5-year post-treatment period, failure of patients with chronic hepatitis to achieve SVR was associated with a 13-fold increase (roughly £2300) in costs, whilst for patients who were retreated, the increase was 56-fold, equating to more than £10 000. Achievement of an SVR has significant effects on health service usage and costs. This work provides real-life data for future cost-effectiveness analyses related to the treatment for chronic HCV infection.

CCR5-Δ32 genotype does not improve predictive value of IL28B polymorphisms for treatment response in chronic HCV infection

IL28B polymorphisms strongly predict spontaneous and treatment-induced clearance of hepatitis C virus (HCV) infection. A recent study proposed a 32-base pair deletion in the CC-chemokine receptor 5 (CCR5) gene (CCR5-Δ32) interacting with the IL28B polymorphisms to influence spontaneous HCV clearance. The aim of this study was to clarify the role of CCR5-Δ32 in treatment-induced clearance of chronic hepatitis C (CHC). A cross-sectional cohort of 813 Caucasian patients with CHC genotype 1 (365 responders and 448 non-responders) who had received standard of care dual therapy with interferon (IFN)-α and ribavirin (RBV) was genotyped for the CCR5-Δ32 and IL28B polymorphisms to examine their interaction with respect to treatment response. CCR5-Δ32 did not influence treatment-induced recovery to IFN-α/RBV in CHC, and did not improve prediction of sustained virological response in the context of the IL28B polymorphisms in a multivariate model. CCR5-Δ32 homozygotes were significantly more frequent in those with CHC than healthy controls in the European cohorts (2.9% vs 0.4%, P<0.0001), but not in Australians of European ancestry. In conclusion, CCR5-Δ32 does not influence treatment response in the context of IL28B polymorphisms. Although CCR5-Δ32 may affect viral clearance within closely controlled geographical and genetic environments, we found no effect in larger cohorts treated with dual therapy.

Autoantibodies in chronic hepatitis C virus infection and their association with disease profile

Autoantibodies are commonly detected in chronic hepatitis C (HCV) but their significance remains uncertain. We assessed the prevalence of anti-nuclear (ANA) and anti-smooth muscle (ASM) antibodies within a cohort of 963 treatment-naïve HCV patients. We also assessed for differences between autoantibody-positive and autoantibody-negative patients in demographics, markers of disease activity and response to anti-viral treatment. One hundred and seventy-two patients (17.9%) had at least one autoantibody, of which were 104 (10.8%) ASM, 54 (5.6%) ANA and 14 (1.5%) positive for both. Autoantibody-positive patients were older (43 vs 39 years, P = 0.001) caused by an age-related increase in ANA (but not ASM). There were no differences in gender, alcohol intake, ethnicity or viral genotype. The presence of autoantibodies, and specifically ASM, was associated with an increase in interface hepatitis score amongst men (1.1 vs 0.8, P = 0.005) but no difference in other necroinflammatory measures, liver function tests or immunoglobulins (Ig). There was no difference in initial fibrosis stage or rate of fibrosis progression. Autoantibodies did not affect response to anti-viral treatment. We conclude that autoantibodies are frequent in HCV infection. Anti-nuclear antibodies increase with age, whereas ASM antibodies are associated with interface hepatitis in men. Neither autoantibody carries increased risk of fibrosis progression or failure of therapy.

Diagnosis of acute hepatitis C virus infection and estimated incidence in low- and high-risk English populations

The diagnosis of acute hepatitis C virus (HCV) infection is not straightforward; few people exhibit clinical symptoms and genome/antigen detection techniques do not indicate when infection had occurred. Here, a strategy to detect HCV RNA in the absence of antibody ('window-period') for diagnosis of acute infection is assessed. The sentinel surveillance of hepatitis testing study was used to retrospectively identify anti-HCV negative samples from high-risk individuals (2002-2003), for testing singly for HCV RNA. Additional samples were identified prospectively (2005) and tested in pools for HCV RNA. Positive samples were genotyped. Incidence and costs of adopting the pooling strategy were estimated. In the retrospective study, 8/390 (2.1%) samples were confirmed HCV RNA positive, anti-HCV negative. Prospectively, 3237 samples were tested in 325 pools. Five positive pools identified four confirmed HCV RNA positive patients (one false positive). Estimated incidence was 12.9 per 100 person-years in injecting drug users (IDUs) (retrospective study) and 3.7 per 100 person-years among drug/alcohol services and prison attendees (prospective study). Estimated costs were pound 850 per positive sample, in areas of higher risk. The yield from a window-period strategy depends upon the population tested. Pooled HCV RNA testing of anti-HCV negative samples from the current IDUs is realistic and relatively inexpensive to identify recently infected individuals.

Acute hepatitis C virus infection

Around 25% of people infected with hepatitis C virus (HCV) are able to clear the infection spontaneously, while the majority become chronically infected, with a subsequent risk for the individual patient of progressive inflammatory liver disease, cirrhosis, hepatocellular carcinoma and liver-related death (Figure 1). Much is known about the epidemiology, pathogenesis, diagnosis and management of chronic HCV infection. In comparison, knowledge about acute HCV infection is patchy. In this article, we will highlight concerns relating to acute HCV infection and suggest that public health bodies responsible for managing the HCV epidemic should redirect at least some of their resources to dealing with these issues.

Association of antibodies to hepatitis C virus glycoproteins 1 and 2 (anti-E1E2) with HCV disease

Hepatitis C virus (HCV) causes acute and chronic liver diseases in humans. Its two envelope glycoproteins, E1 and E2, provide a target for host immune recognition. HCV genotypes are classified into six genetic groups. To study the role of anti-HCV E1 and E2 (anti-E1E2) in HCV disease, the correlation between antibody level and viral load, genotype, disease severity and response to treatment was investigated. The levels of antibodies to HCV glycoproteins E1 and E2 antibodies were evaluated in 230 sera of patients with chronic hepatitis C by enzyme-linked immunosorbent assay. The antigens used were recombinant HCV glycoproteins derived from genotype 1 (H77c) and genotype 3 (UKN3A1.28). Seroreactivity was greater when sera were tested against antigen derived from their homologous genotype than against heterologous antigen. Reactivity against UKN3A1.28 in sera from patients infected with genotype 3 was significantly higher than corresponding reactivity between patients infected with genotype 1 and H77c. The seroreactivity was inversely proportional to the viral load and to the degree of liver fibrosis. The pre-treatment level of anti-E1E2 was higher in sustained responders to combination therapy. These results demonstrate that seroreactivity against E1E2 depends upon the genotypic origin of the E1E2 antigens and the infecting genotype, and suggest a possible protective effect of anti-E1E2 against disease progression.

Response rates to combination therapy for chronic HCV infection in a clinical setting and derivation of probability tables for individual patient management

Evidence for efficacy of established treatment guidelines for chronic hepatitis C virus (HCV) disease is based on multinational randomized controlled trials (RCTs). Strategies for managing HCV, however, require an assessment of the effectiveness of intervention in routine clinical practice. We report the outcomes of combination therapy in a large cohort of HCV-infected individuals in the UK. A total of 347 (113 genotype 1, 234 genotype non-1) patients were treated with pegylated interferon and ribavirin according to current guidelines. Forty-two (37.2%) of those with genotype 1 infection and 164 (70.1%) with genotype non-1 infection achieved sustained viral response (SVR). Thirty-nine (11%) patients withdrew from treatment. In addition to viral genotype, factors predictive of a response to therapy were age at start of treatment and disease stage on pretreatment liver biopsy. Multivariate regression analysis demonstrated that the effects of age [odds ratio 0.5; 95% confidence interval (0.31-0.82) per 10-year increment (P = 0.006)] were confined to genotype 1 disease. In order to further inform the management of the individual patient, a multivariate logistic model was used to predict the probability of SVR for subgroups defined by disease stage, genotype and age at commencement of therapy. This model revealed striking differences in predicted response rates between subgroups and provided a strong rationale for early treatment, particularly for those with genotype 1 disease. Our study demonstrates that results comparable with those of RCTs can be achieved in clinical practice, and suggests that prediction of response rates based on probability modelling will provide a valuable adjunct to individual patient management.

Severe fibrosis in hepatitis C virus-infected patients is associated with increased activity of the mannan-binding lectin (MBL)/MBL-associated serine protease 1 (MASP-1) complex

Mannan-binding lectin (MBL) binds microorganisms via interactions with glycans on the target surface. Bound MBL subsequently activates MBL-associated serine protease proenzymes (MASPs). A role for MBL in hepatitis C virus (HCV) infection had been indicated by previous studies examining MBL levels and polymorphisms in relation to disease progression and response to treatment. We undertook this study to investigate a possible relationship between disease progression and functional MBL/MASP-1 complex activity. A functional assay for MBL/MASP-1 complex activity was employed to examine serum samples from patients with chronic HCV infection, non-HCV liver disease and healthy controls. Intrapatient consistency of MBL/MASP-1 complex activity levels was assessed in sequential samples from a subgroup of patients. Median values of MBL/MASP-1 complex activity were higher in sera from patients with liver disease compared with healthy controls. MBL/MASP-1 complex activity levels correlate with severity of fibrosis after adjusting for confounding factors (P = 0.003). MBL/MASP-1 complex activity was associated more significantly with fibrosis than was MBL concentration. The potential role of MBL/MASP-1 complex activity in disease progression is worthy of further study to investigate possible mechanistic links.

Acute hepatitis C virus infection: a neglected disease?

A better understanding of the epidemiology and natural history of acute hepatitis C virus infection is vital for effective assessment of the impact of policies designed to reduce transmission

Clinical pathways for patients with newly diagnosed hepatitis C - what actually happens

Management of hepatitis C virus (HCV)-infected individuals requires referral to specialist care. To determine whether patients newly diagnosed as anti-HCV positive are appropriately referred for further investigation and management, and if not, to determine why not. We studied patients tested for antibodies to HCV by Nottingham Public Health Laboratory in a 2-year period (2000-2002). The progress of newly diagnosed anti-HCV positive patients into specialist clinics for further management was documented. For patients not referred for specialist care, a questionnaire was sent to the clinician requesting the initial anti-HCV test, to identify reasons for nonreferral. Eleven thousand one hundred and seventy-seven patients were tested for anti-HCV. Two hundred and fifty-six (2.3%) were newly diagnosed as being anti-HCV positive. Two per cent of samples sent from primary care were anti-HCV positive, compared to 18.8, 18.9 and 1.3% sent from prison, drug and alcohol units, and secondary care, respectively. About 64.3% of positive patients diagnosed in primary care were referred to specialist care, compared to 18.4, 42.4 and 62.6% of patients diagnosed in the other three settings. One hundred and twenty-five (49%) newly diagnosed patients were referred appropriately for further management. 68 of these attended clinic, 45 underwent liver biopsy and 26 (10%) began treatment. One hundred and thirty-one patients (51%) were not referred. In 54 cases, there was no evidence that the anti-HCV positive result reached the patient. In 15, referral was considered but rejected, and 20 patients were referred to non-HCV-specialists (their general practitioners or to genito-urinary medicine). Hence less than 50% of newly diagnosed anti-HCV positive patients are referred to an appropriate clinic for further investigation and management. Reasons for this are multifarious and complex, reflecting both systems failure and patient choice. Unless these are understood and addressed, the Department of Health Hepatitis C Strategy (2002) and Action Plan for England (2004) will fail to achieve their intended objectives.

Progression of hepatic fibrosis in patients with hepatitis C: a prospective repeat liver biopsy study

BACKGROUND

The natural history of hepatitis C virus (HCV) infection remains uncertain. Previous data concerning rates of progression are from studies using estimated dates of infection and single liver biopsy scores. We prospectively studied the rate of progression of fibrosis in HCV infected patients by repeat liver biopsies without intervening treatment.

PATIENTS

We studied 214 HCV infected patients (126 male; median age 36 years (range 5-8)) with predominantly mild liver disease who were prospectively followed without treatment and assessed for risk factors for progression of liver disease. Interbiopsy interval was a median of 2.5 years. Paired biopsies from the same patient were scored by the same pathologist.

RESULTS

Seventy of 219 (33%) patients showed progression of at least 1 fibrosis point in the Ishak score; 23 progressed at least 2 points. Independent predictors of progression were age at first biopsy and any fibrosis on first biopsy. Factors not associated with progression were: necroinflammation, duration of infection, alcohol consumption, alanine aminotransferase levels, current or past hepatitis B virus infection, ferritin, HCV genotype, and steatosis or iron deposition in the initial biopsy.

CONCLUSIONS

One third of patients with predominantly mild hepatitis C showed significant fibrosis progression over a median period of 30 months. Histologically, mild hepatitis C is a progressive disease. The overall rate of fibrosis progression in patients with hepatitis C was low but increased in patients who were older or had fibrosis on their index biopsy. These data suggest that HCV infection will place an increasing burden on health care services in the next 20 years.

Interferon plus amantadine versus interferon alone in the treatment of naïve patients with chronic hepatitis C: a UK multicentre study

BACKGROUND/AIMS

The antiviral agent amantadine may have activity against the hepatitis C virus. To determine whether the combination of interferon-alpha plus amantadine was more effective than interferon monotherapy we conducted a multicentre clinical trial in untreated patients with chronic hepatitis C infection.

METHODS

We performed a pilot study in two centres (36 patients) to determine the number needed for a statistically significant clinical trial and then conducted a multicentre, randomized controlled clinical trial involving 14 centres and 143 patients.

RESULTS

There was no significant difference in sustained response rates in patients receiving interferon and amantadine compared to those receiving interferon alone. The on treatment response rate at 3 months was 65% on combination vs. 49% on interferon alone (P = 0.05) while the sustained response was 18 and 15%, respectively.

CONCLUSIONS

Combination therapy with interferon plus amantadine does not lead to a significant increase in sustained response rates when compared to interferon monotherapy.

Direct ex vivo comparison of the breadth and specificity of the T cells in the liver and peripheral blood of patients with chronic HCV infection

The role of intrahepatic lymphocytes in the control of hepatitis C virus (HCV) infection and the pathology associated with it is not understood; most studies of the immunology of this infection use peripheral blood lymphocyte populations. To address this further, we examined in detail the IHL from HCV-infected patients and controls, focusing on the antigen-specific CD8(+) T lymphocyte component. Individual T cells from needle liver biopsies and peripheral blood were isolated from patients with chronic HCV infection and examined directly ex vivo. We used RT-PCR spectratyping to compare the breadth of the T cell receptor usage in the liver in comparison with the peripheral blood, and applied MHC class I tetramer technology to investigate the numbers of HCV-specific CD8(+) cells in the two compartments. T cell receptor usage in the liver of HCV-infected patients was broad, comparable with that in the peripheral blood of the same patients. A much higher proportion of liver CD8(+) cells expressed receptors specific for HCV antigens compared with paired peripheral blood CD8(+) cells. A greater proportion of the liver tetramer-positive cells expressed the activation marker CD69, compared with those in the periphery or other CD8(+) cells in the liver. In the course of chronic HCV infection, HCV-specific CD8 cells, which have been recently activated, appear to accumulate specifically in the livers of infected patients but are present in much lower numbers in the peripheral circulation. Further studies are needed to determine the function of these cells and their role in protection and immunopathology.

Direct ex vivo comparison of the breadth and specificity of the T cells in the liver and peripheral blood of patients with chronic HCV infection

The role of intrahepatic lymphocytes in the control of hepatitis C virus (HCV) infection and the pathology associated with it is not understood; most studies of the immunology of this infection use peripheral blood lymphocyte populations. To address this further, we examined in detail the IHL from HCV-infected patients and controls, focusing on the antigen-specific CD8(+) T lymphocyte component. Individual T cells from needle liver biopsies and peripheral blood were isolated from patients with chronic HCV infection and examined directly ex vivo. We used RT-PCR spectratyping to compare the breadth of the T cell receptor usage in the liver in comparison with the peripheral blood, and applied MHC class I tetramer technology to investigate the numbers of HCV-specific CD8(+) cells in the two compartments. T cell receptor usage in the liver of HCV-infected patients was broad, comparable with that in the peripheral blood of the same patients. A much higher proportion of liver CD8(+) cells expressed receptors specific for HCV antigens compared with paired peripheral blood CD8(+) cells. A greater proportion of the liver tetramer-positive cells expressed the activation marker CD69, compared with those in the periphery or other CD8(+) cells in the liver. In the course of chronic HCV infection, HCV-specific CD8 cells, which have been recently activated, appear to accumulate specifically in the livers of infected patients but are present in much lower numbers in the peripheral circulation. Further studies are needed to determine the function of these cells and their role in protection and immunopathology.

Direct ex vivo comparison of the breadth and specificity of the T cells in the liver and peripheral blood of patients with chronic HCV infection

The role of intrahepatic lymphocytes in the control of hepatitis C virus (HCV) infection and the pathology associated with it is not understood; most studies of the immunology of this infection use peripheral blood lymphocyte populations. To address this further, we examined in detail the IHL from HCV-infected patients and controls, focusing on the antigen-specific CD8(+) T lymphocyte component. Individual T cells from needle liver biopsies and peripheral blood were isolated from patients with chronic HCV infection and examined directly ex vivo. We used RT-PCR spectratyping to compare the breadth of the T cell receptor usage in the liver in comparison with the peripheral blood, and applied MHC class I tetramer technology to investigate the numbers of HCV-specific CD8(+) cells in the two compartments. T cell receptor usage in the liver of HCV-infected patients was broad, comparable with that in the peripheral blood of the same patients. A much higher proportion of liver CD8(+) cells expressed receptors specific for HCV antigens compared with paired peripheral blood CD8(+) cells. A greater proportion of the liver tetramer-positive cells expressed the activation marker CD69, compared with those in the periphery or other CD8(+) cells in the liver. In the course of chronic HCV infection, HCV-specific CD8 cells, which have been recently activated, appear to accumulate specifically in the livers of infected patients but are present in much lower numbers in the peripheral circulation. Further studies are needed to determine the function of these cells and their role in protection and immunopathology.

Development of a strand-specific RT-PCR based assay to detect the replicative form of hepatitis C virus RNA

The recent development of tagged RT-PCR and rTth RT-PCR has greatly improved strand-specific detection of hepatitis C virus (HCV) RNA but these assays are still prone to some false detection of the incorrect strand of RNA. In this study we aimed to address additional factors which contribute towards false detection of HCV RNA. Firstly the benefits of both tagged primers and the thermostable reverse transcriptase rTth during cDNA synthesis were combined and it was found that strand specificity was greatly improved without compromising sensitivity. The reliability of the assay was then optimised by addressing the following issues: control synthetic transcripts should be free of contaminating plasmid DNA, residual RT activity should be minimised in the presence of PCR primers and cDNA should be free of unincorporated tagged RT primer prior to PCR amplification. The alterations made to the assay eliminated completely false detection of the incorrect strand of RNA in the control assay whilst the correct strand was consistently detected at a cDNA dilution of 10(-3)-10(-4). Negative strand was not detected in RNA isolated from serum but was detected, at a ten-fold lower level than positive strand, in RNA isolated from liver tissue.

Influenza virus infection in the second and third trimesters of pregnancy: a clinical and seroepidemiological study

OBJECTIVE

To determine whether maternal influenza virus infection in the second and third trimesters of pregnancy results in transplacental transmission of infection, maternal auto-antibody production or an increase in complications of pregnancy.

DESIGN

Case-control cohort study.

POPULATION

Study and control cohorts were derived from 3,975 women who were consecutively delivered at two Nottingham teaching hospitals between May 1993 and July 1994. A complete set of three sera was available for 1,659 women.

METHODS

Paired maternal ante- and postnatal sera were screened for a rise in anti-influenza virus antibody titre by single radial haemolysis and haemagglutination inhibition. Routine obstetric data collected during and after pregnancy were retrieved from the Nottingham obstetric database. Cord samples were tested for the presence of IgM anti-influenza antibodies, and postnatal infant sera were tested for the persistence of influenza-virus specific IgG. Paired antenatal and postnatal sera were tested against a standard range of auto-antigens by immunofluorescence.

MAIN OUTCOME MEASURES

Classification of women as having definite serological evidence of an influenza virus infection in pregnancy (cases) or as controls.

RESULTS

Intercurrent influenza virus infections were identified in 182/1,659 (11.0%) pregnancies. None of 138 cord sera from maternal influenza cases was positive for influenza A virus specific IgM. IgG anti-influenza antibodies did not persist in any of 12 infant sera taken at age 6-12 months. Six of 172 postnatal maternal sera from cases of influenza were positive for auto-antibodies. In all cases the corresponding antenatal serum was also positive for the same auto-antibody. There were no significant differences in pregnancy outcome measures between cases and controls. Overall, there were significantly more complications of pregnancy in the cases versus the controls, but no single type of complication achieved statistical significance.

CONCLUSIONS

Influenza infection in the second and third trimesters of pregnancy is a relatively common event. We found no evidence for transplacental transmission of influenza virus or auto-antibody production in pregnancies complicated by influenza infections. There was an increase in the complications of pregnancy in our influenza cohort.

Immunisation with phage displaying peptides representing single epitopes of the glycoprotein G can give rise to partial protective immunity to HSV-2

Filamentous phage displaying peptides representing single epitopes of the glycoprotein G of HSV-2 (gG2) were used as immunogens via the subcutaneous route in Balb/c mice without additional adjuvant. The phage were isolated from a random phage peptide display library and contain 15-mer peptide inserts that mimic epitopes of gG2. In each case, an antibody response to gG2 was generated that was dependent on the dose of phage administered and on the presence of the peptide insert. Phage displaying epitopes of gG2, which map to amino acids 551-570, were the most immunogenic; interestingly, this region of gG2 is frequently recognised by patients infected with HSV-2. The data also provide interesting information as regards choice of peptide mimics for use as immunogens because, surprisingly, the most antigenic of the individual clones was the least immunogenic. In two of the experiments, mice immunised with phage displaying a single epitope of gG2 were protected against challenge with a lethal dose of whole HSV-2. This suggests a possible role for phage-displayed peptides in inducing protective immunity against pathogens and provides a model system for investigating the underlying mechanisms.

HIV-1 in semen: determination of proviral and viral titres compared to blood, and quantification of semen leukocyte populations

This study was carried out to determine the relationship between proviral DNA and viral RNA titres in semen compared with blood. In addition, the association between semen leukocyte counts with detection frequency and absolute levels of human immunodeficiency virus type 1 (HIV-1) nucleic acids was also assessed. Paired samples of blood and semen were collected from a cohort of individuals with different blood CD4 cell counts, and whose anti-HIV therapy had not changed in the preceding 3 months. The cell-associated proviral DNA titres and cell-free plasma viral RNA titres were determined using nested primer polymerase chain reaction and NASBAtrade mark, respectively. In addition, leukocyte counts were determined by immunocytochemical and cytochemical staining of a subset of semen samples. HIV-1 proviral DNA was detected in 100% and 47%, and viral RNA was detected in 76% and 63%, of blood and semen samples tested, respectively. HIV-1 proviral DNA and viral RNA titres in blood were higher than in corresponding semen samples, although the difference observed in viral RNA titres was not statistically significant. Proviral DNA and viral RNA titres were correlated between the two body fluids, and within the semen, although some individuals had disparate semen and blood titres or detection rates, indicating genital tract compartmentalisation. In addition, detection of HIV-1 proviral DNA, but not of HIV RNA, in semen was associated with elevated semen leukocyte counts, although this latter finding requires verification in future studies of larger numbers of patients.

Poor reduction of HIV-1 RNA titres in nucleoside reverse transcriptase inhibitor experienced patients treated with indinavir combination therapy

OBJECTIVES

The long term effectiveness of combination therapy at reducing viral loads in seminal fluid and blood plasma obtained from HIV-1 infected men who had undergone previous antiretroviral therapy was assessed.

METHODS

Samples of semen and blood were obtained from a cohort of 12 nucleoside reverse transcriptase inhibitor experienced men before and during 25-68 weeks of combination therapy, which included the protease inhibitor indinavir. HIV-1 RNA titres present in the cell free blood and seminal plasma samples were determined using the nucleic acid sequence based amplification (NASBA)/Nuclisens assay system.

RESULTS

Viral RNA was detected in 9/12 and 7/12 baseline blood plasma and seminal plasma samples, with median viral titres of 10(4.81) and 10(4.56) per ml, respectively. By the end of the study period the detection rates of HIV RNA in the blood and seminal plasma samples were 5/12 and 2/12, respectively, with the median viral titres below the assay cut off level for both sample types. Of the nine patients who had detectable viral RNA in the baseline sample, only three cleared virus from both compartments by the end of the study.

CONCLUSIONS

These data show that stable reduction of blood and seminal fluid viral titres is not achievable in a significant proportion of nucleoside reverse transcriptase inhibitor experienced men.

Identification of type-specific domains within glycoprotein G of herpes simplex virus type 2 (HSV-2) recognized by the majority of patients infected with HSV-2, but not by those infected with HSV-1

A combination of phage peptide display library mapping and pepscanning, with both murine monoclonal antibodies and a panel of well-characterized human sera, have been used in order to define type-specific epitopes of glycoprotein G of herpes simplex virus type 2 (HSV-2) (gG2). Both techniques revealed an immunodominant region of gG2, centred around amino acids 525-587 of the uncleaved gG2 molecule. A soluble peptide, equivalent to amino acids 551-570, when used as antigen in an ELISA format was recognized by three out of five murine MAbs and by 20/26 (77%) Western blot anti-HSV-2-positive human sera, but by only 1/63 Western blot anti-HSV-2-negative sera (specificity, 98%). The sensitivity of detection of human anti-HSV-2 antibodies was increased to 90% using a peptide derived from this region, presented on a nitrocellulose membrane. This highly antigenic and type-specific domain of gG2 is located at the junction between the 'unique' region of gG2 and its C-terminal end, which has approximately 50% identity with gG1. A second antigenic region of gG2, amino acids 351-427, which lies within the 'unique' part of gG2, was also identified by both techniques employed in this study and is recognized by a proportion of anti-HSV-2-positive sera. These findings demonstrate the feasibility of developing a peptide-based type-specific assay for the detection of anti-HSV-2 antibody in human sera based on type-specific epitopes of gG2 and have implications for the understanding of the three-dimensional topography of gG2.

TT virus sequence heterogeneity in vivo: evidence for co-infection with multiple genetic types

TT virus (TTV) is a newly described DNA virus of humans that exhibits an unusually high degree of genetic heterogeneity. We have performed extensive analysis of the TTV populations present in samples, taken over a period of 2 to 6 years, from three individuals with persistent TTV infection. TTV DNA titres estimated for sequential samples were found to be quite stable over the entire study period in two patients, but fluctuated considerably in the third. DNA sequence analysis revealed different genetic diversity among TTV populations from samples from the three patients. In one case, absolute sequence homogeneity was observed among samples over a 3 year period. In a second, a limited amount of heterogeneity was found, including one sequence exhibiting G-->A hypermutation. TTV DNA sequences from the third patient exhibited quite remarkable genetic heterogeneity: evidence was found of seven distinct infecting viruses, representing four of the six TTV genotypes that have been described. In addition, minor variants of three of these seven sequences were observed. The heterogeneity of the viral population in this individual declined steadily over a 6 year period. This patient infected with a genetically diverse TTV population had the highest viral DNA titre.

TT virus infection in patients with hepatitis C: frequency, persistence, and sequence heterogeneity

TT virus (TTV) was recently identified in the serum of a patient with hepatitis. The role of TTV in liver disease has not been established. Three polymerase chain reaction (PCR) protocols were used to detect TTV DNA in sera of persons infected with hepatitis C virus (HCV) and in blood donors. Sera from 11.5% of HCV-infected patients and 7.7% of blood donors were positive by protocols 1 or 2. In contrast, 48.7% and 57.7% of sera, respectively, were positive when tested by protocol 3. There was no difference in the severity of hepatitis in persons coinfected with TTV and HCV when compared with those infected with HCV alone, regardless of which TTV PCR protocol was used. TTV DNA persisted in serum samples taken up to 6 years apart in individual patients. Sequence analysis indicated that most viral sequences were distinct between patients, and there was evidence of genetic heterogeneity and viral evolution within individuals.

GBV-C/HGV coinfection in HIV-1-positive men: frequent detection of viral RNA in blood plasma but absence from seminal fluid plasma

Sequential paired samples of blood and seminal fluid were obtained from a cohort of 54 HIV-1-infected homosexual males. The prevalence of GBV-C/HGV RNA in the cell-free fractions of some of these patients was determined using reverse-transcription polymerase chain reaction (RT-PCR). To assess the effects of HIV-1 and HCV infection upon GBV-C/HGV RNA status, blood CD4 cell counts, HCV RNA status, and HIV-1 proviral DNA and viral RNA titres were also determined. GBV-C/HGV RNA was detected in 8/30 (27%) of the blood plasma samples obtained at the start of the study, and was present at a frequency of 14/64 (22%) in all the blood plasma samples tested. By contrast, GBV-C/HGV RNA was not detected in the 26 seminal fluid samples obtained at the start of the study, including 8 samples obtained from patients for which GBV-C/HGV RNA was detected in the corresponding blood sample. Of the samples tested for the presence of both GBV-C/HGV and HCV RNA, there was no evidence of coinfection. Although GBV-C/HGV RNA detection rates were significantly higher in individuals with blood CD4 cell counts greater than 200 cells per microlitre, there were no significant differences in the median blood CD4 cell counts or HIV-1 proviral DNA or viral RNA titres observed between the GBV-C/HGV-positive and -negative individuals. The failure to detect GBV-C/HGV RNA in seminal fluid samples obtained from this cohort would suggest that further studies need to be carried out to determine the roles of sexual transmission and of seminal fluid in GBV-C/HGV infection.

Effect of genotypes on the quantification of hepatitis C virus (HCV) RNA in clinical samples using the Amplicor HCV Monitor Test and the Quantiplex HCV RNA 2.0 assay (bDNA)

The Amplicor HCV Monitor test and the Quantiplex HCV RNA 2.0 (bDNA) assay are two commercially available assays for the quantification of hepatitis C virus (HCV) RNA in clinical samples. A direct comparison of the two assays was carried out using sera frozen previously from patients known to be chronically infected with HCV. Overall, 61 samples from 51 patients were tested simultaneously by the two methods: 67% (28/42) of the patients were infected by HCV genotype/serotype 1, 10% (4/42) with type 2, and 24% (10/42) with type 3. When the absolute value from each assay was examined, the Quantiplex assay gave a consistently higher reading and the mean logarithmic difference between the two assays was 1.4 (1.0 in type 1, 2.0 in type 2, and 2.2 in type 3). When analyzed according to genotype, strong correlation was observed between the two assays for type 1 (r = 0.83, 95% CI 0.63-0.93, P < 0.01), but not for nontype 1 samples. Despite the difference in absolute level reported by the two assays, there was a consistent trend of change in HCV RNA concentration by both assays in patients whose consecutive samples were analyzed and the differences between the two assays in consecutive samples were within 0.4 log of each other. The results suggested that with samples containing genotype 1, the Amplicor assay was more sensitive than the Quantiplex assay by about one log. However, the sensitivities of the two assays with nontype 1 samples were much closer probably due to the failure of the Amplicor assay to quantify nontype 1 genotypes effectively.

Association between MHC class II alleles and clearance of circulating hepatitis C virus. Members of the Trent Hepatitis C Virus Study Group

The frequencies of HLA class I antigens and class II haplotypes were compared in subjects with previous (polymerase chain reaction [PCR]-negative) or with persistent (PCR-positive) hepatitis C virus (HCV) infection and in HCV patients with mild versus severe histologic activity scores on liver biopsy. The DRB1*11 allele group was found in 11 (31.4%) of 35 subjects with previous infection and in 11 (8.2%) of 135 subjects with persistent infection (P < .001). The DQB1*0301 allele was found in 18 (51.4%) of 35 subjects with previous infection and in 33 (24.4%) of 135 patients with persistent infection (P < .002). Both observations remained significant after correction for multiple testing. No significant association was shown between severity of disease and any HLA class I or II type. Thus, the HLA class II alleles DRB1*11 and DQB1*0301 are associated with clearance of circulating HCV.

Chronic hepatitis in children after liver transplantation: role of hepatitis C virus and hepatitis G virus infections

BACKGROUND/AIMS

Chronic graft hepatitis occurs in 20-30% adults after liver transplantation but the prevalence and causes in children are not known. In adults, hepatitis C virus infection is prevalent prior to transplantation and recurrent infection is a frequent cause of graft dysfunction. The significance of the recently described hepatitis G virus infection remains unproven. The aim of this study was to examine the role of hepatitis C virus and hepatitis G virus infection in chronic graft hepatitis after paediatric liver transplantation.

METHODS

The prevalence of graft hepatitis and the role of hepatitis C virus and hepatitis G virus infections in 80 children after liver transplantation have been studied, with a median follow up of 4.4 years (range 0.4 to 10.7), and the persistence of hepatitis G infection in the presence of immunosuppression has been determined.

RESULTS

Chronic graft hepatitis was diagnosed in 19/80 (24%) children and was most frequently seen in children transplanted for cryptogenic cirrhosis (71%). There was no significant difference in the prevalence of chronic hepatitis in those transplanted before or after donor anti-HCV screening. Hepatitis C infection occurred in three children transplanted prior to donor screening but in only one was associated with chronic hepatitis. Hepatitis G infection was found in 22/79 (28%) transplant recipients but was not associated with graft hepatitis. In 17/21 children hepatitis G infection persisted for a median of 5.2 years after transplantation.

CONCLUSION

Chronic hepatitis occurred in 24% of children after liver transplantation, a similar prevalence to that in adults. Cryptogenic liver disease predisposed to graft hepatitis, but neither hepatitis C nor hepatitis G infection was associated. Hepatitis G virus caused a frequent and usually persistent infection after transplantation.

Hepatitis G infection: role in cryptogenic chronic liver disease and primary liver cell cancer in the UK. Trent Hepatitis C virus Study Group

Hepatitis G virus (HGV) is a flavivirus that can cause acute hepatitis and persistent infection but its role in chronic liver disease or primary liver cancer is unproven. In this study we have examined the prevalence of HGV RNA in the serum of patients with hepatitis C virus (HCV) infection and in patients with cryptogenic chronic liver disease, including non-alcoholic steatohepatitis (NASH), and in patients with HCV-related hepatocellular carcinoma (HCC) and HCC arising in patients with cryptogenic liver disease. One-hundred and thirty patients who were positive for antibody to HCV (anti-HCV), 54 patients with cryptogenic chronic liver disease (including 17 patients with NASH) and 46 patients with hepatitis C-related (n = 27) or cryptogenic liver disease-related HCC (n = 19) were studied. HGV RNA was detected using nested reverse transcriptase-polymerase chain reaction (RT-PCR) and was found in 16.1% of patients with HCV infection. HGV RNA was not detected in any patient with cryptogenic liver disease. In patients with HCC, 7/34 samples were positive for HGV RNA and six out of seven HGV-positive subjects also had HCV infection. Only one patient with HCC in cryptogenic liver disease was positive for HGV RNA. Hence, cryptogenic liver disease in the UK is not caused by HGV/GBVc infection. It seems unlikely that HGV plays a significant role in hepatocarcinogenesis.

Dendritic cells cultured from mononuclear cells and CD34 cells in myeloma do not harbour human herpesvirus 8

Dendritic cells (DC) are antigen-presenting cells with the potential to be a powerful adjuvant in the immunotherapy of haematological malignancy, including myeloma. Recently, human herpesvirus 8 (HHV-8) infection of dendritic cells in the long-term bone marrow stromal cultures of patients with myeloma has been reported. This finding is of great potential importance regarding oncogenesis in myeloma in addition to having significant implications for the use of DC in the immunotherapy of this disease. Therefore DC generated from mobilized blood mononuclear cells (MO-DC) and purified CD34+ cells (CD34-DC) of myeloma patients were examined for the presence of HHV-8 using a sensitive PCR technique. HHV-8 was not demonstrated in MO-DC or CD34-DC and we conclude that these cells remain a suitable vehicle for investigation in the immunotherapy of myeloma.

The presence of rheumatoid factor in sera from anti-HCV positive blood donors interferes with the detection of HCV-specific IgM. Trent HCV Study Group

BACKGROUND/AIMS

IgM anti-HCV has been reported as a useful marker of disease activity and of likely response to interferon therapy in patients with chronic hepatitis C virus infection. Sera from patients with hepatitis C virus infection may contain rheumatoid factor. This study was designed to investigate the possible effect of rheumatoid factor in an IgM anti-HCV assay.

METHODS

Sera from 75 blood donors with chronic hepatitis C virus infection were tested for the presence of IgM anti-HCV using a core-derived peptide as antigen, before and after removal of IgG. These sera and appropriate control sera were also tested for the presence of rheumatoid factor.

RESULTS

Removal of IgG prior to IgM testing resulted in a significant loss of reactivity in the IgM anti-HCV assay in 30/41 sera that were positive in this assay when tested untreated. Seventy per cent of anti-HCV positive sera were also positive for rheumatoid factor.

CONCLUSIONS

Rheumatoid factor causes significant false positive reactivity in IgM anti-HCV detection assays. The results of assays that do not account for this interference should be viewed with caution.

Studies to show that with podophyllotoxin the early replicative stages of herpes simplex virus type 1 depend upon functional cytoplasmic microtubules

The antiviral activity of podophyllotoxin against herpes simplex type 1 virus (HSV-1) grown in Vero cells was studied by a simple microtitration assay. Antiviral effects were induced at similar concentrations as direct cellular toxicity, as characterised by a time-dependent loss of cell monolayer. Podophyllotoxin-mediated toxicity arises from cytoplasmic microtubular, and hence cytoskeletal, decay. Some degree of selectivity was seen for inhibition of virus replication over direct cellular toxicity. Podophyllotoxin acted against an early viral process, as an antiviral effect was still seen if drug was removed 2 h after infection. Similar effects were seen with colchicine, a classical tubulin-binding compound, but not with bromovinyldeoxyuridine. Podophyllotoxin was capable of inducing a cytoprotective effect in Vero cells, as pre-treatment of cells abrogated virus growth for up to 90 min after removal of drug. This is coincident with the repolymerisation of cellular microtubules and re-formation of the cytoskeleton. We conclude that HSV-1 relies upon a functional cellular cytoskeleton for efficient completion of an early replicative event. Such a process may be the transport of viral material to the nucleus or inhibition of the formation of intranuclear viral 'replication factories', bodies containing cytoskeletal fragments constructed after viral infection.

Serum HCV RNA levels assessed by quantitative NASBA: stability of viral load over time, and lack of correlation with liver disease. The Trent HCV Study Group

BACKGROUND/AIMS

We used the hepatitis C virus quantitative NASBA technique to evaluate the stability of viral load within individuals with chronic hepatitis C, to determine the range of viraemic load between individuals, and to assess the usefulness of hepatitis C virus RNA quantitation in predicting the severity of underlying hepatitis C virus-induced liver disease.

METHODS

Hepatitis C virus RNA was determined, using the quantitative NASBA assay, in multiple serum samples from 11 individuals with chronic hepatitis C over an average time period of 11 months (range = 3-23 months), and in single serum samples from a further 10 individuals.

RESULTS

In 10/11 individuals the hepatitis C virus RNA titres were within one log10 copies/ml of each other during this time period. In the eleventh, there was a rise of 1.36 log10 copies/ml in two serum samples taken 8 months apart. The viraemic load varied by 2.79 log10 copies/ml serum between individuals. There were no correlations between mean RNA levels and total biopsy scores (either Knodell or Sheffield scores), or the individual components of the biopsy scoring systems, except the sinusoidal infiltration component of the Sheffield score. There was also no difference in viral RNA levels between those infected with type 1 as compared to type 3 virus, with a mean level in both groups of 7.2 log10 copies/ml.

CONCLUSIONS

Hepatitis C virus serum RNA level is stable within individuals within the studied time period. Viral load varies between infected individuals but is not a useful prognostic indicator of the severity of virus-induced liver disease.

Enhanced expression of MHC class I molecules on cultured human thyroid follicular cells infected with reovirus through induction of type 1 interferons

Certain viruses are known to modulate the cellular expression of MHC molecules. We have investigated whether reovirus types 1 or 3 can alter the normal MHC molecule expression on cultured human thyroid follicular cells (TFC). Primary TFC cultures were established from eight human thyroid donors and MHC class I and II expression was assessed by indirect immunofluorescence microscopy. Both types of reovirus enhanced MHC class I expression on TFC from all thyroid donors. Class II MHC protein was strongly induced by type 1 reovirus on TFC from one donor, while weak induction of expression, by either reo-1 or reo-3 virus, was noted on the TFC of five other donors. Studies on the mechanism(s) of MHC class I hyperexpression showed that mouse MoAb against the type 3 reovirus haemagglutinin (anti-HA3) reduced the ability of the virus to induce hyperexpression of class I MHC molecules on TFC. However, supernatant harvested from type 3 reovirus-infected TFC cultures maintained its ability to enhance class I expression after incubation with anti-HA3. Moreover, adding rabbit anti-sera to interferon-alpha (IFN-alpha) or IFN-beta inhibited the increased class I MHC expression on TFC by both types of reovirus. These data suggest that reoviruses (types 1 and 3) can enhance MHC class I on cultured TFC. The mechanism of MHC class I enhancement is most probably through the release of IFN-alpha and IFN-beta.

Dual infection with human herpesvirus type 6 and parvovirus B19 in a renal transplant recipient

A 7-year-old boy developed intermittent fever and rashes 2 weeks after anti-lymphocyte globulin therapy for a transplant rejection episode. Dual infection with parvovirus B19 and human herpesvirus type 6 was suggested by serological tests. Neither virus has been reported previously in a symptomatic paediatric renal transplant recipient.