Selection of high-avidity CD8 T cells correlates with control of hepatitis C virus infection

Both strong antigenic avidity and acquisition of proper effector functions contribute to the efficacy of antiviral T cell responses. To correlate these parameters with the outcome of hepatitis C virus (HCV) infection, we characterized HCV-specific CD8 T cell lines isolated after immunomagnetic sorting of peripheral blood mononuclear cells from human leukocyte antigen A*02 (HLA-A*02) individuals with various HCV serological statuses, using recombinant HLA-A*0201 multimers loaded with three immunodominant HCV genotype 1-derived epitopes. CD8 T cells specific for these three epitopes were derived from most HLA-A*0201 individuals, regardless of their HCV serology or clinical outcome. Donors recovered from genotype 1 HCV infection were enriched for high-avidity T cells with enhanced interferon gamma (IFN-gamma), tumor necrosis factor alpha, and cytotoxic T lymphocyte responses, when compared with seronegative donors and seropositive patients infected with irrelevant HCV genotypes. Patients chronically infected with genotype 1 strain yielded almost exclusively low-avidity T cells, whose hyporesponsiveness was primarily attributable to low T cell receptor (TCR) avidity rather than intrinsic functional defects.

CONCLUSION

This study suggests that strong IFN-gamma responses associated with efficient viral clearance primarily result from Ag-driven selection/survival of HCV-specific T cells expressing high-avidity TCR. It also suggests a link between the quality of the initial HCV-specific T cell repertoire and susceptibility to chronic infection.

Expertise of laboratories in viral load quantification, genotyping, and precore mutant determination for hepatitis B virus in a multicenter study

A national evaluation study was performed in 14 specialized laboratories with the objective of assessing their capacities to provide (i) hepatitis B virus (HBV) viral loads (VL), (ii) HBV genotypes, and(iii) identification of precore/core mutants. The panel consisted of 12 HBV DNA-positive samples with VLs from 2.8 to 9.1 log(10) copies/ml, different HBV genotypes (A to F), and 3 mutant and 9 wild-type samples at nucleotide 1896. The coefficients of variation of the mean VLs ranged from 2.4% to 10.4% with the Cobas HBV Monitor assay, from 1.8% to 5.5% with the Cobas TaqMan 48, from 1.5 to 26.2% with RealArt HBV PCR, and from 0 to 7% with branched DNA (bDNA). The Cobas Monitor assay underestimated the VLs of genotype F samples, with differences ranging from 1.4 to 2.4 log(10) copies/ml. The accuracies of genotype determinations ranged from 33% to 100%, and those of precore mutant determinations ranged from 25 to 100%. This study showed some drawbacks of two widely used assays: (i) Cobas Monitor has a narrow dynamic range and underestimates genotype F sample VLs and (ii) bDNA shows poor sensitivity and may fail to identify patients with low VLs. With higher performance in terms of analytical sensitivity combined with a larger dynamic range and an ability to quantify the main genotypes equally, real-time PCR methods appear more appropriate for accurate monitoring of HBV DNA quantification. Furthermore, the clinical implications of HBV genotyping and the determination of precore/core mutants need to be clearly stated to justify the standardization of these methods.

Molecular evolution of hepatitis A virus: a new classification based on the complete VP1 protein

Hepatitis A virus (HAV) is a positive-stranded RNA virus in the genus Hepatovirus in the family Picornaviridae So far, analysis of the genetic variability of HAV has been based on two discrete regions, the VP1/2A junction and the VP1 N terminus. In this report, we determined the nucleotide and deduced amino acid sequences of the complete VP1 gene of 81 strains from France, Kosovo, Mexico, Argentina, Chile, and Uruguay and compared them with the sequences of seven strains of HAV isolated elsewhere. Overall strain variation in the complete VP1 gene was found to be as high as 23.7% at the nucleotide level and 10.5% at the amino acid level. Different phylogenetic methods revealed that HAV sequences form five distinct and well-supported genetic lineages. Within these lineages, HAV sequences clustered by geographical origin only for European strains. The analysis of the complete VP1 gene allowed insight into the mode of evolution of HAV and revealed the emergence of a novel variant with a 15-amino-acid deletion located on the VP1 region where neutralization escape mutations were found. This could be the first antigenic variant of HAV so far identified.

Evaluation of chronic hepatitis B virus (HBV) infection in coinfected patients receiving lamivudine as a component of anti-human immunodeficiency virus regimens

The effect of lamivudine on chronic coinfection with hepatitis B virus (HBV) in human immunodeficiency virus (HIV)--infected patients was studied prospectively. Nineteen patients with HIV infection, who were receiving an anti-HIV regimen containing lamivudine (150 mg twice daily), and who had replicative chronic HBV infection, were followed for a median of 14 months. Twelve patients' regimens contained protease inhibitors. Serum HBV DNA became undetectable, by means of molecular hybridization, in 14. Seroconversion of hepatitis B e antigen to antibody occurred in 6 of 17 patients, and seroconversion of hepatitis B surface antigen to antibody occurred in 1 of 19. The median serum alanine aminotransferase concentration had decreased by the time of the final evaluation. The median CD4 cell count increased and plasma HIV RNA was undetectable in 10 of 19 patients. Five patients had recurrence of detectable serum HBV DNA despite good compliance with treatment, and 2 mutations related to the resistance of HBV were detected. These patients had a significantly longer duration of treatment (21 versus 13 months; P<.05). In conclusion, resistant strains of HBV emerge at high detectable levels while patients receive anti-HIV regimens containing lamivudine.

[Viral hepatitis B. Risk for the anesthetist]

The risk of hepatitis B, previously reported in other countries, has never been investigated in French anaesthetic medical staff. The prevalence of hepatitis B viral markers has been calculated among the medical staff of the Department of Anaesthesiology, the hospital health care personnel, patients before surgical procedure and renal transplantation patients. The frequency in anaesthesiologists (18.75%; 12 out of 64) was significantly greater (p less than 0.05) than in health care personnel (10.5%; 91 out of 863). Prevalence increased with the length of practice in anaesthesiology. Prevalence of markers is 8.7% (27 out of 196) in patients undergoing surgery and 82% (27 out of 33) in patients operated on for renal transplantation in 1981. Frequency of carriers of the hepatitis B surface antigen is 0% in medical staff, 0.2% in health care personnel and 0.5% in patients before surgery. Among the health care staff, anaesthesiologists belong to a high risk population for hepatitis B. Prevention by administration of hepatitis B vaccine is recommended to protect the anaesthesiologist, his relatives and his patients.

[Gougerot-Sjögren's syndrome. Clinical and biological correlations with the serology of Yersinia infections]

An unusual case of Sjögren's syndrome (SS) induced or revealed by a Yersinia pseudotuberculosis serotype IV infection has prompted the authors to undertake a retrospective study of 32 patients with that syndrome. High titers of antibodies to Y. pseudotuberculosis serotype IV (greater than 1/200 th) were found in 4 patients with primary Sjögren's syndrome and Sharp's syndrome. Seven other patients (5 with primary Sjögren's syndrome, 1 with systemic lupus erythematosus and 1 with Sharp's syndrome) had positive serology with low titres, of doubtful significance. Serology was negative in the 20 remaining patients. Nine out of 25 patients had anti-thyroid antibodies, and their relationship with positive Y. pseudotuberculosis IV serology is discussed. The responsibility of the infection in the induction or disclosure of Sjögren's syndrome may be considered. However, since the syndrome frequently develops before serology becomes positive (8/12 cases with a 1 to 6 years' follow-up), an alternative hypothesis would be that diminished digestive defences in Sjögren's syndrome result in an increased frequency of Yersinia infections.