31/08/2009 EPATITI (Picornaviridae; Hepadnaviridae; Flaviviridae; Caliciviridae) EPATITI scaricato da www.sunhope.it 1 31/08/2009 …ma vari altri virus possono causare epatite • • • • • • • • • CMV EBV HSV VZV Adenovirus Virus della Rosolia Virus della Parotite Virus delle febbri emorragiche Enterovirus (cox e echo) scaricato da www.sunhope.it 2 31/08/2009 EPATITI EPATITI scaricato da www.sunhope.it 3 31/08/2009 Virus dell’epatite A (HAV) Hepatitis A virus (HAV) particles observed by immune electron microscopy. Virus-like particles, 27 to 32 nm in diameter, are arranged in a crystalline array, with antibody coating their surfaces. These HAV particles appear to have cubic symmetry and have capsomeres measuring 8 to 12 nm Phylogenetic relationship of hepatitis A virus (HAV) and simian HAV (SHAV) to representative species of the mammalian picornavirus genera scaricato da www.sunhope.it 4 31/08/2009 ¾Non-Enveloped ¾Simmetria icosaedrica ¾+RNA ¾Baltimore Class.: IV Virus appartenente alla famiglia Picornaviridae scaricato da www.sunhope.it 5 31/08/2009 Ciclo replicativo 1. 2. Il virus si lega al recettore cellulare Sito e meccanismo di scapsulamento ignoti 3. La proteina VPg (pallino arancione) viene rimossa e l’RNA si associa ai ribosomi 4. Inizia la traduzione e viene prodotta una poliproteina 5. Taglio proteolitico della poliproteina 6. Le proteine che partecipano alla sintesi dell’RNA virale vengono trasportate a delle vescicole 7. La sintesi dell’RNA avviene sulla superficie di queste vescicole dove è anche stato trasportato l’RNA+ 8 8. Avviene la sintesi del filamento negativo 9. Il filamento – serve come stampo per la sintesi di quello + 10. Le proteine strutturali vengono utilizzate nella fase di assemblaggio 11. insieme all’RNA genomico 12. Per uscire infine dalla cellula mediante lisi cellulare 10 11 12 Acute viral hepatitis. Lobular disarray characterized by anisocytosis, anisonucleosis, ballooning, and Kupffer cell hypertrophy Acute viral hepatitis. Ballooned hepatocytes show lysis of cell membranes and nuclei and an empty cytoplasm Acute viral hepatitis. Two sinusoidal acidophilic (apoptotic) bodies can be seen in the center of the field scaricato da www.sunhope.it 6 31/08/2009 Acute viral hepatitis. Portal area infiltrated with numerous inflammatory cells Acute viral hepatitis with submassive necrosis. Zones of necrosis are linked together (bridging necrosis) Acute viral hepatitis with massive necrosis. All liver cells have “dropped out.” Note proliferating periportal cholangioles and infiltration of stroma and portal areas with inflammatory cells Immunologic and clinically relevant biologic events associated with hepatitis A virus (HAV) infection in humans scaricato da www.sunhope.it 7 31/08/2009 Rates of reported hepatitis A cases (per 100,000 population) in the United States, by race/ethnicity, 1997 scaricato da www.sunhope.it 8 31/08/2009 Distribution of viral hepatitis cases in the United States reported to the Centers for Disease Control and Prevention in 1998 scaricato da www.sunhope.it 9 31/08/2009 Virus dell’epatite B (HBV) scaricato da www.sunhope.it 10 31/08/2009 Virus con envelope Vi l Simmetria icosaedrica Dna circolare parzialmente bicatenario (filamento lungo DNA - ; filamento corto DNA +) Baltimore Class.: I Il filamento corto si completa solo nell’imminenza della replica del DNA virale scaricato da www.sunhope.it 11 31/08/2009 DNA polimerasi presente nel virione DNA parentale circolare e parzialmente p bicatenario RNA polimerasi cellulare DNA circolare bicatenario superspiralizzato ( + ) RNA pre-genomico Replicazione HBV RNA messaggero Varie proteine funzionali Transcriptasi inversa DNA polimerasi DNA della progenie virale Progenie virale scaricato da www.sunhope.it 12 31/08/2009 Ciclo replicativo Pathology of chronic hepatitis B A: Necrosis (Arrowheads indicate lymphocytic infiltrates disrupting the limiting plate of the portal area and invading the parenchyma) B Lymphoid B: L h id aggregates. t (Arrowhead A h d shows a dense lymphoid aggregate in the portal area surrounding the bile duct) C: Lobular inflammation. Scattered apoptotic hepatocytes (arrowheads) with surrounding lymphocytes D: Cirrhosis. Thick bands of fibrotic tissues (arrowhead) encircling regenerative nodules E: Ground-glass hepatocytes F: Fibrosing cholestatic hepatitis. Diffuse ballooning degeneration of hepatocytes scaricato da www.sunhope.it 13 31/08/2009 scaricato da www.sunhope.it 14 31/08/2009 Serologic and clinical patterns observed during acute HBV infection. scaricato da www.sunhope.it 15 31/08/2009 scaricato da www.sunhope.it 16 31/08/2009 scaricato da www.sunhope.it 17 31/08/2009 scaricato da www.sunhope.it 18 31/08/2009 Natural history and growth of HCC in HBsAg-positive carriers. scaricato da www.sunhope.it 19 31/08/2009 Virus dell’epatite C (HCV) Acido nucleico Simmetria del capside Envelope Struttura del genoma Classificazione di Baltimore Polimerasi virale Diametro D m del virione (nm) ( m) Dimensione del genoma (kb) scaricato da www.sunhope.it RNA Icosaedrico + ss (+) IV 40-50 10 20 31/08/2009 Altri virus appartenenti alla famiglia Flaviviridae Flaviviridae scaricato da www.sunhope.it 21 31/08/2009 Flaviviridae VIRUS DELL’EPATITE C FLAVIVIRUS HCV virioni rotondeggianti, 40-50 nm di diametro RNA ( + ) monocatenario lineare di 10 Kb con pericapside replicazione citoplasmatica Ac anti HCV Trasmissione parentale Incubazione b i 20-40 20 0 gg Molto probabile la latentizzazione AG nel fegato mesi INF Fino al 1990 (anno di introduzione dello screening) l’ HCV era la causa del 60-90% di epatiti PT. scaricato da www.sunhope.it 22 31/08/2009 GENOTIPI di HCV HCV è un virus molto eterogeneo perché molto mutante •Sei Sei genotipi maggiori, sulla base dell dell’analisi analisi filogenetica delle regioni del core, E1 e NS5 •Ogni genotipo è suddiviso in sottotipi minori •Altro tipo di variabilità, le quasi-specie, cioè varianti spontanee o indotte dalla terapia e presenti nel singolo paziente infetto In Italia i genotipi più frequentemente trasmessi sono il genotipo 1 e il genotipo 3, essendo il genotipo 1 quello più rappresentato nella nostra popolazione e il genotipo 3 quello selezionatosi più recentemente nei giovani. Estimated incidence of acute hepatitis C virus infections in the United States between 1982 and 1996 scaricato da www.sunhope.it 23 31/08/2009 Proportion of acute hepatitis C cases related to selected risk factors in the United States between 1983 and 1996. Before testing, transfusion accounted for about 20% of acute non-A, non-B hepatitis C cases. At present, transfusion associated hepatitis C has been virtually eliminated Representation of clinical responses in patients after infection in acute (A) and chronic (B) hepatitis C scaricato da www.sunhope.it 24 31/08/2009 Typical histologic features of chronic hepatitis C A: Portal area with a lymphoid aggregate B: Portal area showing necrosis. necrosis The edge of the portal area is disrupted by lymphocytic infiltration. infiltration Within the portal area is a lymphoid aggregate surrounding a duct that shows reactive epithelial changes. This “duct injury” is termed a Poulsen lesion. It is not associated with chronic cholestasis or duct loss C: Lobular inflammation. Small foci of inflammation are seen within the hepatic parenchyma in chronic hepatitis C D: Steatosis. Accumulation of intracellular lipid within hepatocytes is a common feature in chronic hepatitis C E: Periportal fibrosis. The earliest fibrotic change in hepatitis C is an expansion of the portal area by fibrosis. This gives the portal area a stellate appearance F: Advanced fibrosis. As the disease progresses, more scarring takes place. Al mondo oltre 80 milioni di donne HCV positive sono in età fertile. In Italia --Æ prevalenza dell’ Infezione da HCV in gravidanza 1-2,4 % Nel 40-50% dei casi non è possibile individuare nessun fattore di rischio, negli altri casi i fattori di rischio sono quelli tipici delle infezioni da HCV: • 30-40% stupefacenti per via endovenosa • < 20% trasfusioni di sangue / emoderivati partner di persona anti HCV positivo tipo di lavoro svolto Il rischio di trasmissione verticale dell’infezione da HCV è circa del 6% Nessun genotipo di HCV è specificamente correlato alla trasmissione verticale. scaricato da www.sunhope.it 25 31/08/2009 The relative proportion of hepatocellular carcinoma cases associated with chronic hepatitis B virus (HBV) or hepatitis C virus (HCV) infections in different countries. Some parts of the world still have relatively high numbers of HBV carriers, resulting in a high proportion of hepatocellular carcinoma HCC cases due to HBV. In other countries such as Japan, HBV is coming under control resulting in a higher proportion of HCC cases related to HCV. scaricato da www.sunhope.it 26 31/08/2009 Location on the HCV polyprotein of recombinant antigens and peptides used in the Ortho enzyme-linked immunosorbent assay (ELISA) (Ortho-Clinical Diagnostics, Rochester, NY) and the Chiron recombinant immunoblot assay (RIBA) antibody test systems (Chiron Corporation, Emeryville, CA). Recombinant antigens are expressed in yeast as fusion proteins with superoxide dismutase; this protein tag is represented by the hatched area. scaricato da www.sunhope.it 27 31/08/2009 Virus dell’epatite D Electron micrograph of the hepatitis delta virus Hepatitis D (Delta) Virus δ antigen HBsAg RNA scaricato da www.sunhope.it 28 31/08/2009 HBV – HDV Coinfection Typical Serologic Course Symptoms ALT Elevated Titre anti-HBs IgM anti-HDV HDV RNA HBsAg Total anti-HDV Time after Exposure HBV - HDV Superinfection Typical Serologic Course Jaundice Symptoms Titre Total anti-HDV ALT HDV RNA HBsAg IgM anti-HDV Time after Exposure scaricato da www.sunhope.it 29 31/08/2009 Structural proteins of the hepatitis delta virus Western blot of serum-derived HDAg with a human monoclonal antibody to HDAg. Extracts of HDAg from sera of five humans infected with HDV (lanes 2 through 6), two chimpanzees (lanes 8 and 9), and an HDVinfected woodchuck (lane 11) were analyzed. Lane 1 contains an extract of an HDV-negative human serum; lane 7, an HDVnegative g chimpanzee p serum; and lane 10, an HDV-negative woodchuck serum. Lane M contains molecular-weight markers, and the relative molecular masses in kilodaltons are indicated on the left margin scaricato da www.sunhope.it 30 31/08/2009 Replication scheme of hepatitis delta virus. 1: Replication begins with transcription of genomic RNA encoding the short form of HDAg (HDAg-S). Two types of antigenomic RNAs are produced: an mRNA that encodes HDAg, and a greater-than-unitlength antigenome. The latter undergoes autocatalytic cleavage via an internal ribozyme and is ligated by a host enzyme to yield circular antigenomes, which then serve as template for genome synthesis by a similar mechanism mechanism. HDAg HDAg-S S is required for RNA replication. 2: The adenosine within the stop codon for HDAg-S is deaminated to inosine in approximately 30% of antigenomic RNAs by a host enzyme. 3: During subsequent RNA transcription, this change appears in the mRNA, which now encodes the long form of HDAg (HDAg-L), which inhibits RNA replication. 4: The C-terminus of HDAg-L is prenylated by a host farnesyltransferase, facilitating interaction with the envelope protein (HBsAg) and subsequent virion formation Typical morula cells from a patient with hepatitis caused by HDV scaricato da www.sunhope.it 31 31/08/2009 The serologic patterns of type D hepatitis: Co-infection and superinfection Top: Coexistent acute hepatitis B and hepatitis D Middle: Acute hepatitis D superimposed on a chronic hepatitis B virus infection Bottom: Acute hepatitis D progressing to chronic hepatitis, superimposed on a chronic hepatitis B virus infection The worldwide distribution of HDV infection, as measured by the prevalence of anti-HDAg in HBsAg-positive individuals with acute or chronic hepatitis scaricato da www.sunhope.it 32 31/08/2009 Geographic distribution of HDV genotypes Circles on the map correspond approximately to geographic origin of isolates. Filled circles, genotype I horizontal stripes, genotype II vertical stripes, genotype III. VIRUS DELL’EPATITE E CALICIVIRUS HEV virus con forma isometrica, 35-40 nm diametro RNA lineare ( + ) monocatenario sprovvisto di peplos replicazione citoplasmatica • • • • trasmessa attraverso il circuito oro – fecale (acqua contaminata) incubazione più lunga di HAV le epidemie colpiscono varie migliaia di persone presente in Asia centrale, USSR, Algeria, Africa centrale, America latina, Borneo, …….. • i colpiti sono gli adulti 15-40 anni • alta mortalità nelle donne in gravidanza diagnosi: esclusione delle altre forme più dati epidemiologici. scaricato da www.sunhope.it 33 31/08/2009 L’HEV è attualmente stato spostato dalla classificazione come Calicivirus ed è tornato ad essere considerato tra gli agenti virali ad RNA non classificati. Acido nucleico Simmetria del capside Envelope Struttura del genoma Classificazione di Baltimore Polimerasi virale Diametro del virione (nm) Dimensione del genoma (kb) RNA Icosaedrica ss (+) IV 35-40 8 Fotografia al microscopio elettronico l tt i d dell virus i dell’epatite E scaricato da www.sunhope.it 34 31/08/2009 In ogni caso la famiglia virale a cui sembra essere più vicino rimane quella dei Caliciviridae CALICIVIRIDAE scaricato da www.sunhope.it 35 31/08/2009 CALICIVIRIDAE Hep E Genome organisation Starting from the 5´ end of ORF 1 and extending to its 3´ end, motifs characteristic of f the f following g viral p proteins have been identified f (55): ¾ A methyl transferase, consistent with the finding that the 5´ end of the viral genome is capped (42) ¾ A Y domain, a sequence of unknown function found in certain other viruses, including rubella virus ¾ A papain-like cysteine protease, a type of protease found predominantly in alphaviruses and rubella virus (35) ¾ A proline-rich “hinge region” that is thought to impart flexibility to the molecule and that contains a region of hypervariable sequence (82 94) (82,94) ¾ An X domain of unknown function that flanks papain-like protease domains in the polyproteins of other positive-strand RNA viruses (35) ¾ A domain containing helicase-like motifs that are most closely related to the helicases of superfamily I (34) ¾ The motifs of an RNA-dependent RNA polymerase, most closely related to supergroup III of viral RNA polymerases (54) scaricato da www.sunhope.it 36 31/08/2009 Hepatitis E Virus Infection Typical Serologic Course Symptoms IgG anti anti-HEV HEV ALT Titer IgM anti-HEV Virus in stool 0 1 2 3 4 5 6 7 8 9 1 0 1 1 1 2 1 3 Weeks after Exposure scaricato da www.sunhope.it 37 31/08/2009 Algorithm for the serologic diagnosis of HAV, HBV, HCV, and HDV. scaricato da www.sunhope.it 38