DEVELOPMENT OF AN INTERNATIONAL REFERENCE PREPARATION FOR HEPATITIS D VIRUS RNA - UPDATE

Transcription

1 DEVELOPMENT OF AN INTERNATIONAL REFERENCE PREPARATION FOR HEPATITIS D VIRUS RNA - UPDATE SoGAT Clinical Diagnostics III January 2011, London Michael Chudy Julia Kreß Micha Nübling Paul-Ehrlich-Institut Federal Institute for Vaccines and Biomedicines WHO Collaborating Centre for Quality Assurance of Blood Products and in vitro Diagnostic Devices

2 Member of the genus Deltavirus 8 major clades (HDV-1 to HDV-8) Hepatitis D Virus (HDV) Genetic variability ranges from 20 to 35% 36 nm defective viral particle; needs HBV to replicate (coinfection or superinfection) Virion is encapsidated by HBsAg (L, M, S) Circular ss (-) RNA genome of ~ 1.7 kb which is encased in 60 molecules HDAg Transmitted via infected blood or blood products; sex contact Gudima et al., J Virol 81: (2007) Individuals at risk are HBV carriers, IDUs, hemodialysis patients and highly promiscuous groups Worldwide ~ 5% of HBV carriers are anti-hdv positive (10-15 million people) Mortality rate lies between 2 and 20% (ten times higher than for HBV) 1

3 HDV Worldwide

4 HDV Infection - Prevention and Treatment No specific vaccine or post-exposure prophylaxis HBV-HDV coinfection can be prevented with HBV vaccine or anti-hbs-ig No effective antiviral therapy is currently available Nucleosid(t)e analogues and other antiviral agents are inefficient Approved treatment for hepatitis D is aifn (PEG- aifn) In cases of end-stage chronic HDV infection liver transplantation could be an option 3

5 Clinical Utility of HDV RNA Quantification Serological tests often lacks on sensitivity The most sensitive method is NAT Identify individuals with active HDV infection Decide to initiate treatment Monitor antiviral treatment efficacy Tailor treatment schedule

6 HDV Genome - Three HDV RNAs 5 Both genome and antigenome are circles with rod-like folding and 74% base-pairing

7 Alignment of HDV-RNA Sequences from the LHD Gene Conserved Target Regions for NAT Schaper et al., J Hepatol 2010;52:

8 HDV NAT Calibration HDV cdna plasmid Synthetic HDV RNA (transcripts) Armored RNA* No reference method for quantification (simple OD measurement is not sufficient!) HDV RNA Reference Preparation (preparation of whole virus in human plasma) IU (arbitrary unitage) geq copies 7 *Armored RNA, complex of MS2 bacteriophage coat protein and RNA; RNA sequences are completely protected from RNase digestion; developed by Ambion company

9 HDV NAT and Standardization NAT assays are usually in-house developed No standardization No proficiency testing program in place HDV RNA quantification currently is unreliable HDV RNA IS is particularly important for assay comparison development and calibration of diagnostic assays calibration of secondary references and working standards evaluation of standardized preparations used in quality control and quality assurance

10 Unmet Needs in Delta Hepatitis Diagnosis and Public Health EASL* Monothematic Conference on Delta Hepatitis (September 24 26, 2010, Istanbul, Turkey) Global Disease Should be on the agenda of WHO Establish international standards in diagnosis of HDV infections Anti-HDV antibody tests in every region of the world; tests have to be as cheap as possible, fast and reliable standardized HDV RNA testing (IS) - HDV RNA quantification is a crucial tool to diagnose, treat and manage HDV infections 9 *European Association for the Study of the Liver

11 Development of the 1 st International Standard for HDV RNA (1) Discussion proposal at Clinical SoGAT II, Sep 2009, Istanbul Adoption of proposal by WHO ECBS in October 2009 Collaboration with the Institute of Hepatology, Ankara University, Turkey (Prof. Bozdayi) Seven HDV-positive plasma samples are available Volume ml Viral load cps/ml (pre-analyzed) All samples represent genotype HDV-1 (sequenced) Further characterization (e. g. HDV RNA, HBV DNA, HBsAg quant, HBe/antiHBe ) 10

12 HDV RNA and Anti-HDV Anti-HDV HDV RNA 1 total 2 Sample (cps/ml) (log 10 cps/ml) (S/CO) N ,78 15,24 N ,72 15,75 N ,33 15,75 N ,21 15,75 N ,70 14,77 N ,60 15,24 N ,33 14,77 1 RoboGene HDV RNA Quantification Kit, 2 Murex Anti-Delta, 11

13 HBV Markers / Anti-HCV / Anti-HIV 1/2 Sample HBV DNA (IU/ml) 1 HBV DNA (IU/ml) 2 HBsAg (IU/ml) 3 Anti-HBc total 4 HBeAg 5 Anti-HBe 6 Anti-HCV 7 Anti-HIV 1/2 8 N pos neg pos neg neg N6357 < pos neg pos neg neg N6358 < pos pos pos neg neg N pos neg pos neg neg N pos neg pos neg neg N6361 < pos neg pos neg neg N6362 < pos neg pos neg neg 1 CAP/CTM, 2 Abbott RealTime, 3 Architect, 4 Architect, 5 Elecsys, 6 Elecsys, 7 Murex, 8 Axsym Ag/Ab Combo 12

14 Comparison of Direct HDV / HBV Markers WHO IS Candidate Materials 13 HDV RNA (copies/ml) HBV DNA / HBsAg (IU/ml)

15 Development of the 1 st International Standard for HDV RNA (2) Feasibility study Two candidate materials (N6357 and N6360) To assess the suitability of candidate materials Parallel testing with armored RNA (N6363) Different labs and different NATs 14

16 Feasibility Study Sample ID HDV RNA (log 10 copies / ml) Lab 1 Lab 2 Lab 3 Lab 4 Lab 5 N6357 7,38 8,72 8,25 7,35 N6360 6,24 7,70 7,81 6,54 N6363 9,75 11,11 8,46 9,99 15

17 Development of the 1 st International Standard for HDV RNA (3) 16 Two materials Dilution in negative plasma pool to a volume of 1.2 litre ( cps/ml) Preparation of 2000 vials each (filling volume 0.5 ml) Filling and lyophilisation by a certified Swiss company Pre-study (PEI): Control of HDV RNA concentration before and after lyo Stability testing programme Residual moisture content: <1% Worldwide collaborative study to evaluate the candidate reference materials - Proposed for Q3-4/ Invitation to NCLs, labs with special diagnostic expertise in viral hepatology, kit manufacturers so far exist, others - Incl. different NAT assays/test platforms - Commutability (genotype inclusivity) Statistical analysis Final report to WHO ECBS in July 2012

18 17 Thank you for your attention!