Features of the HDV RNA Extensive Base-Pairing Transcribed by host RNA Polymerase II Self-cleavage of RNA by internal ribozyme elements A G RNA Editing

HDV RIBOZYME A ribozyme structurally and biochemically related to the HDV ribozyme is present in an intron of the human CPEB3 gene, which belongs to a family of gene regulating messanger RNA polyadenilation. HDV EVOLVED FROM THE HUMAN TRANSCRIPTOME? HDV EVOLVED FROM A SMALLER VIROID, ACQUIRED HD-AG AND RIBOZYME THROUGH RECOMBINATION WITH THE HUMAN TRANSCRIPTOME? Brazas R, 1996 Salehi-Ashtian K, 2006

HDV RIBOZYME The only catalytic cleaving RNA motif discovered in humans, ideal for use as a functional enzyme in an intracellular environment HDV sequences in the human CPEB3 gene, not recognized as an external, invading RNA HDV sequences in the human CPEB3 gene, not recognized as an external, invading RNA functions properly in the low-ionic enviroment of human cells functions properly in the low-ionic enviroment of human cells more stable and longer half life than hammerhead or hairpin ribozymes more stable and longer half life than hammerhead or hairpin ribozymes HDV RIBOZYME AS A GENE INACTIVATION TOOL

Replication Scheme of HDV CXXX

HDV-proteins: functions promote elongation RNA Pol II promote elongation RNA Pol II proteins interactions proteins drive to nucleus RNA binding promote replication promote replication promote virion formation promote virion formation coiled-coil domains coiled-coil domains bipartite nuclear localization signal bipartite nuclear localization signal activation of reporter genes activation of reporter genes arginine-rich motifs arginine-rich motifs

How can HDV proteins orchestrate the life- cycle of HDV? By post-translational modifications: HDAg/HDV-RNA = ONE-GENE GENOME phosphorilation acetylation methylation prenylation

HDV: unique features in human virology Smallest infectious agent in man Similar to viroids and satellite RNAs of plants Infectious at serum dilutions in HBsAg + Rolling circle mechanism of replication Self-cleaving and self-ligating ribozyme Transcription by a host-RNA polymerase II

HDV virion assembly requires: On HDV side: Prenylation (farnesylation) of the terminal CXXX box of Large HD-Ag Integrity of critical regions of the HBsAg On HBV side:

HDV VIRION ASSEMBLY: blocked in-vitro and in-vivo by prenylation inhibitors inhibited by changes in SW 196 L/S of the small HBsAg induced by Lamivudine Glenn JS, 2006 Vietheer PT, 2005

Global Anti-HDV Prevalence in HBsAg Carriers (15,000,000 Positive)

Modified from: Radjef et al., 2004, and Pujol et al., 2005

Drug addicts

% % 14% 1992 N° patients tested 8% Prevalence of anti-HD in HBsAg-carriers with liver disease in Italy % Smedile 1983 Sagnelli 1992 Sagnelli 1997 Gaeta

Prevalence changes of anti-HD in CHB and LC in Turkey within the years Degertekin H et al, 2006 CHB: Chronic hepatitis B, LC: Liver cirrhosis % anti-HD (n° examined) CHB31% (204) 19.4% (4271) 11% (1486) LC43.3% (302) 26.1% (157) 24% (805)

Decline in HDV Prevalence: Control of HBV Improved socio- economic and hygienic conditions Precautions for the control of HIV Universal HBV vaccination

IN THE DEVELOPING WORLD No control of HDV as long as HBV remains unchecked Significant presence of HDV reported in the last 4 years from: PAKISTAN 1 INDIA 2 MONGOLIA 3 IRAN 4 VIETNAM 5 TAJIKISTAN 6 TUNISIA 7 MAURETANIA 8 1. Zuberi BF, 2006; 2. Acharya SK, 2006; 3.Tsatsralt-Od B, 2006; 4. Roshandel G, 2007; 5. Nguyen VT, 2007; 6. Khan A, 2008; 7. Djebbi A, 2009; 8. Lunel F, personal communication

11% % % 14% 1992 N° patients tested 8% 2001 Prevalence of anti-HD in HBsAg-carriers with liver disease in Italy % Smedile 1983 Sagnelli 1992 Sagnelli 1997 Gaeta 2000 Sagnelli

Wedemeyer H, 2007

Contemporary HDV, North-Europe Anti-HD/HBsAg+HDV origin Hanover % (253/2354) 26% Turkey 28% East Europe 1. Wedemeyer H., 2007; 2. Cross TJS, 2008; 3. London % (87/962) 28.1% South, East Europe 26.8% Africa 7.3% Middle East

Contemporary HDV: France origin of 617 anti-HD+ patients Le Gal F, 2007 Africa West Europe East Europe Asia

IN EUROPE: ageing domestic survivors of the epidemic ageing domestic survivors of the epidemic young immigrants from HDV endemic areas recapitulating florid hepatitis D young immigrants from HDV endemic areas recapitulating florid hepatitis D Significant residual reservoir of HDV, composed of two HBsAg pools:

2010s : immigrants 2009