Diagnostic couplé des virus grippaux et du SARS-CoV-2 : évaluation de 2 tests moléculaires

Introduction

Matériels et méthodes

Résultats

Conclusion

Clinical severity and molecular characteristics of circulating and emerging rotaviruses in young children attending hospital emergency departments in France

Group A rotavirus (RVA) is the leading cause of acute gastroenteritis in young children worldwide. A prospective surveillance network has been set up to investigate the virological and clinical features of RVA infections and to detect the emergence of potentially epidemic strains in France. From 2009 to 2014, RVA-positive stool samples were collected from 4800 children <5 years old attending the paediatric emergency units of 16 large hospitals. Rotaviruses were then genotyped by RT-PCR with regard to their outer capsid proteins VP4 and VP7. Genotyping of 4708 RVA showed that G1P[8] strains (62.2%) were predominant. The incidence of G9P[8] (11.5%), G3P[8] (10.4%) and G2P[4] (6.6%) strains varied considerably, whereas G4P[8] (2.7%) strains were circulating mostly locally. Of note, G12P[8] (1.6%) strains emerged during the seasons 2011-12 and 2012-13 with 4.1% and 3.0% prevalence, respectively. Overall, 40 possible zoonotic reassortants, such as G6 (33.3%) and G8 (15.4%) strains, were detected, and were mostly associated with P[6] (67.5%). Analysis of clinical records of 624 hospitalized children and severity scores from 282 of them showed no difference in clinical manifestations or severity in relation to the genotype. The relative stability of RVA genotypes currently co-circulating and the large predominance of P[8] type strains may ensure vaccine effectiveness in France. The surveillance will continue to monitor the emergence of new reassortants that might not respond to current vaccines, all the more so as all genotypes can cause severe infections in infants.

Natural variability of NS3 protease in patients infected with genotype 4 hepatitis C virus (HCV): implications for antiviral treatment using specifically targeted antiviral therapy for HCV

To analyze the genetic diversity of the NS3 gene in patients infected with hepatitis C virus (HCV) genotype 4 (HCV-4) and to assess the possible effects of the gene polymorphism (or variability) on drug susceptibility, 43 NS3 gene sequences were determined for 53 selected patients with HCV-4 infection. NS3 sequencing, like NS5B sequencing, allowed correct subtype determination. Most residues that were located within the catalytic triad or the NS4-binding region or that were involved in metal binding were highly conserved and identical to those found in HCV genotype 1. Compared with HCV genotype 1, all HCV-4 NS3 protein presented V36L and C16T residue changes that could potentially reduce antiprotease activity. The efficacy of antiprotease in HCV-4-infected patients remains to be proven in large clinical trials.

Intérêt d'un nouveau test combiné antigène–anticorps pour le dépistage de l'infection par le virus de l'hépatite C : réduction de la fenêtre sérologique au cours de l'hépatite C aiguë chez le sujet co-infecté par le VIH

BACKGROUND

The aim of this study was to determine the clinical benefit of a new combined antigen-antibody immunoenzymatic assay (Monolisa HCV Ag-Ab Ultra, Biorad) in the setting of acute HCV infection in HIV infected patients.

PATIENTS AND METHODS

The performance of this assay was first evaluated in 160 HIV positive samples from uninfected and chronically HCV infected patients. To assess the performance of the Ag-Ab assay in the context of acute hepatitis C, 94 stored frozen serums from 20 recently diagnosed cases were retrospectively tested for HCV-RNA and presence of anti-HCV antibodies, in parallel with the new assay.

RESULTS

In HIV infected patients, the sensitivity and specificity of the Ultra assay was 100% with a strong discrimination between positive and negative samples. In HCV acutely infected patients, the Ag-Ab assay significantly reduced the seronegative period, allowing an earlier diagnosis compared to a 3rd generation ELISA in 65% of the cases. The combined assay became positive on the same bleed as the first HCV-RNA detection for 13 patients out of 20. Nevertheless, in one case, characterized by an absence of seroconversion over one year but a continuous viral replication above 1 million IU/ml, the combined assay did not improve HCV infection diagnosis.

CONCLUSION

Use of this new assay as a first line screening would significantly reduce the long seronegative window period seen in HCV infection allowing earlier HCV diagnosis and rapid clinical management. However, in case of clinical acute hepatitis C, sensitive HCV-RNA detection should remain the gold standard.

Early detection of hepatitis C virus infection by use of a new combined antigen-antibody detection assay: potential use for high-risk individuals

The performance of a new combined antigen-antibody assay (Monolisa HCV Ag-Ab Ultra; Bio-Rad Laboratories) was evaluated in the context of acute hepatitis C in human immunodeficiency virus-infected patients. The combined assay became positive as early as the first PCR and earlier than a third-generation enzyme-linked immunosorbent assay in 65% of the cases. Reduction of the long period of HCV seronegativity should improve the diagnosis of hepatitis C infection, especially in high-risk populations.

Genetic heterogeneity of the hypervariable region I of Hepatitis C virus and lymphoproliferative disorders

B-cell lymphoproliferative disorders (BCLD) have been associated with chronic hepatitis C virus (HCV) infection. The HCV glycoprotein E2 (gpE2) hypervariable region I (HVR-I) may be a potential antigenic candidate to promote B-cell proliferation. The purpose of this study was to analyze the influence of HVR-I sequence variability in the development of BCLD. HVR-I sequences were studied in 29 chronically HCV-infected patients with (n=15) or without (n=14) BCLD. After PCR amplification of the gpE2 region, analysis of the 81 bp HVR-I encoding fragment was performed on 7-18 clones per patient. HVR-I sequence complexity was slightly lower in patients with BCLD (mean 0.347) than without (0.468) (P=0.2), though, sequence diversities were similar (0.0370 vs 0.0954, P=0.239). Phylogenetic analysis did not reveal any BCLD-associated clustering. In our population, neither the recently described insertion between positions 1 and 2 of HVR-I nor residues at positions 4 and 13 were particularly linked to BCLD. As previously described, we confirm the high degree of conservation of HVR-I residues T-2, G-6 and G-23 in our patients. Contrary to recent findings, our analysis based on multiple clones per patient analysis did not reveal any particular motif associated with BCLD.