-HCV genome is about 9400 nucleotides long, it is ssrna and positive sense -the 10 viral proteins are first made as a large polyprotein -individual

Transcription

1

2 2013:

3

4 HCV Genome -HCV genome is about 9400 nucleotides long, it is ssrna and positive sense -the 10 viral proteins are first made as a large polyprotein -individual proteins are released from polyprotein by cellular and viral proteases -core, E1 and E2 are the structural proteins which form the virus particle -remaining proteins are nonstructural and have roles in viral replication

5 HCV protein and its function

6

7 HCV Variability Marked genetic heterogenity due to hyper variable region RNA virus, RDRP lacks proof-reading function Mutations arise during replication are not corrected Genotypes genetically divergent HCV isolates that can be grouped phylogenetically

8 HCV Genotypes and Quasispecies Term Genotype Subtype Quasispecies Definition Heterogeneity among different viruses Closely related viruses within each genotype Complex of genetic variants within individual viruses Nucleotide Similarity 66% 69% 77% 80% 91% 99%

9 Hepatitis C Genotypes HCV genotypes are substantially divergent in sequence from each other and fall into 6 phylogenetic clades, designated as genotypes More than 70 subtype are identified (21 unclassified)genotype dictates length of therapy and predicts therapeutic response Genotype 1 requires longer therapy and has lower response

10 GENOTYPES 1 and 2: global distribution 1a: west europe 1b: USA and japan, blood transfusion 3a: asia, infects injecting drug users 4: middle east and africa 5: south africa 6: east asia In Iran : 1a: 49% 3a: 34% 1b: 13% 4: 0.4%

11 In acute phase Clinical symptoms Just about 15% of HCV cases are acute infection Clinical features of acute hepatitis divide into four stages: 1. incubation period: (50) days, RNA are detected after 1-2 w asymptomatic, anti HCV negative 1. Pre- icteric period: elevate LFT level, non specific symptoms, 1. Icteric period: urine darkness and jaundice occurs, in 80% of cases Bili level at least 3mg/dl and ALT elevate 600IU, HCV RNA are positive but anti-hcv exist only in 50-70%, 4-6 weeks 2. Convalescent period: recovery of symptom, normalized LFT,

12 Acute Infection Symptoms Natural History Are uncommon On average, appear 6 to 7 weeks after infection. Testing 6 to 8 weeks: Average time antibodies can be detected. 1 to 3 weeks: Average time virus can be detected. 4 to 12 weeks: Often elevation in ALTs 15 to 25 percent of people resolve acute infection.

13 Serologic Pattern of Acute HCV Infection with ihrecovery Symptoms +/- anti-hcv HCV RNA Titer ALT Normal Months Years Time after Exposure

14 chronic c phase 85% of cases, patients not able clear virus and after 6 mounts cause viremia and persistent infection with highest ALT level and HCV-RNA positive Factors that cause chronically infections aren't distinct to know but: virus quasispecies, susceptibility of E gene to rapid mutation and immune system dodging Gradually progressing disease and absence of symptoms first two decades are critical characteristics Tiredness and lethargy are most common Cirrhosis (20-30% o patients) Severity indicators of disease are ambiguous

15 Chronic Infection Natural History Diagnosed by the detection of HCV RNA in the blood for at least six months. 60 to 70 percent of people will have persistent or fluctuating ALT elevations. Chronic liver disease usually progresses at a slow rate without symptoms. Estimated that 10 to 20 percent of people will develop cirrhosis 20 to 30 years after infection. The rate of progression is highly variable.

16 Serologic Pattern of Acute HCV Infection with Progression to Chronic Infection Symptoms +/- anti-hcv HCV RNA Titer ALT Normal Months Years Time after Exposure

17 Natural History Factors that Influence Progression Greater than age 40 at time of infection Male gender Alcohol use Co-infection with HIV or HBV Co-morbid conditions such as obesity Factors that Don t Influence Progression Viral load Genotype

18 FULMINANT VIRAL HEPATITIS Rare and occurs in less than 1% of fit icterici hepatitis infections Severe, progressive manifestation of vial hepatitis Causes extensive liver necrosis Liver may suddenly become smaller Marked in prothrombine time (PT), that does not improve with vitamin K Ftlit Fatality approaches 80%

19 Transmission How is hepatitis t C being transmitted?

20 Routes of Transmission Injecting drug use 60% Sexual l15% Transfusion 10% (before screening) Occupational 4% Other 1%* Unknown 10% * Nosocomial; iatrogenic; perinatal Source: Centers for Disease Control and Prevention

21 HCV Testing Who oshould oud be tested?

22 CDC Testing Recommendations Testing Routinely Recommended Based on Risk of Infection Person who ever injected illegal drugs Persons with selected medical conditions Persons who received clotting factor concentrates Persons who were ever on long-term hemodialysis Persons with persistently abnormal alanine aminotransferace levels (persons with chronic liver disease) Prior recipients of transfusions or solid organs Persons who were notified that they received blood from a donor who later tested positive for HCV infection

23 CDC Testing Recommendations Testing Routinely Recommended Based on Need for Exposure Health care, emergency medical, and public safety workers after needlesticks, sharps, or mucosal exposures to HCV positive blood Children born to HCV positive women

24 HCV Testing

25 Diagnostic methods of HCV infection Specific and non-specific tests are available: specific Non-specific serologic Liver enzyme virologic Genotype determination Liver biopsy Liver radiograp hy

26 The role of testing in diagnosis i and treatment t t Method Screen Confirm Duration of therapy Predicting sustained response Assessing treatment response HCV antibody test (EIA) X PCR: HCV genotype X PCR: HCV RNA qualitative assay X X PCR: HCV RNA quantitative assay X

27 HCV Testing Initial Screening Negative Result A negative test most likely means that a person is not infected. False negatives are uncommon. May occur if a person has been recently infected. May occur in individuals who are immunosuppressed or on long-term hemodialysis.

28 HCV Testing Initial Screening - Positive Result False positives are uncommon. Most likely to occur in individuals at low-risk for infection. May occur in individuals with autoimmune liver disease. A positive test, especially in a person with known risk factors, most likely means that they have been exposed to the virus. Screening test results can be verified with a supplemental or confirmatory test.

29 HCV Testing Confirmatory Testing To ensure that a positive screening test result is a true positive. To distinguish between a resolved and an active infection. They can be used alone or more than one test can be used.

30 Virologic Detection of HCV-RNA are most useful particularly when Ab is not produced PCR Gold standard d of HCV recognition is RT-PCR There are two qualitative and quantitative RT-PCR for HCV recognition Qualitative: Amplicor HCV test and Cobas Amplicor HCV test Quantitative: RT-PCR

31 Testing Asymptomatic People EIA (-) No HCV (+) (+) RT-PCR (-) Active HCV Infection (+) RIBA (-) (Probable) Prior HCV Infection with Recovery False Positive EIA No Exposure

32 Liver Biopsy Liver Biopsy Most sensitive measure of disease severity. Used to determine stage of fibrosis. Can be used to help predict natural history of disease. Often used to determine the need for treatment. Can also be used to predict response to treatment.

33 Tests asessing liver damage Noninvasive tests of fibrosis and activity Panel of biochemical markers, e.g. FibroTest Ultrasonography, e.g. FibroScan Liver biopsy Gold standard for grading inflammation Gold standard for grading inflammation and disease stage

34 Staging g of Fibrosis on Liver Biopsy Stage Histology 0 No fibrosis 1 M inim al fibrosis 2 Moderate fibrosis 3 Moderate to Severe fibrosis 4 Cirrhosis

35 Histologic Progression of HCV Normal Mild Chronic Hepatitis Moderate Chronic Hepatitis Cirrhosis

36 Role of liver biopsy in HCV infection Confirm clinical diagnosis Assess severity of fibrosis and necroinflammation1 Associated risks: bleeding <1% death % 2 Role of liver biopsy in HCV infection Can aid decision making Evaluate possible concomitant disease processes (e.g., alcoholic liver disease) Assess therapeutic intervention 1

37 Treatment Who oshould oud be treated?

38 Contraindications to treatment Patients in whom HCV therapy is currently contraindicated include: Pregnant patients Patients with severe uncontrolled systemic diseases Patients t with known hypersensitivity to drugs used to treat HCV

39 Treatment Treatment Goal To prevent complications of infection; principally achieved by eradication of the virus. HCV is considered to be eradicated when there is a Sustained Viral Response (SVR). An SRV is defined as the absence of detectable HCV RNA (virus) six months after treatment ends. A qualitative viral detection test is used for this purpose.

40 Pegylated interferon and ribavirin Peginterferon alfa-2a (40KD) PEGASYS Ribavirin Subcutaneous injection, By mouth, once weekly twice daily

41 Evolution of hepatitis C treatment Discovery of HCV genome Treatment with IFN alfa for 24 or 48 weeks 3x weekly dosing Poor outcomes Addition of RBV to IFN alfa improved outcomes Peg IFN mono once weekly dosing Peg IFN alfa plus RBV becomes gold standard Response guided therapy emerging New antivirals enter development

42 Evolution of hepatitis C treatment NS3 protease inhibitor classes include: - linear covalent(boceprevir and telaprevir), - linear noncovalent(asunaprevir) - macrocyclic inhibitors (vaniprevir) inhibitor of NS5A: Daclatasvir Daclatasvir is a potent inhibitor of NS5A that was used, in combination with asunaprevir

43 Treatment Side Effects Common Side Effects of Peginterferon Occurring in more than 10 percent of patients Fatigue Muscle aches Headaches Nausea and vomiting Skin irritation on injection site Low-grade fever Weight loss Depression Mild bone marrow suppression Hair loss

44 Treatment Side Effects Common Side Effects of Ribavirin Occurring in more than 20 percent of patients Anemia Fatigue and irritability Itching Rash Nasal stuffiness, sinusitis, and cough Ribiviran can cause birth defects Must use strict contraceptive methods during treatment and for six months after.

45 In January 2004, the role of occult hepatitis C virus (HCV) if infection in chronic liver disease of unknown etiology in approximately 10% of cases with abnormal LFTs was first described d by Castillo et al.. This cases was termed cryptogenic liver hepatitis

46 This occult infection can be present in two different clinical situations: I. in anti-hcv negative: serum HCV-RNA negative patients with abnormal liver function tests II. and in anti-hcv positive subjects with normal values of liver enzymes and without serum HCV RNA

47 In 57 of 100 patients t who were negative for anti-hcv antibodies and for serum HCV RNA and who had occult HCV infection, as demonstrated by the detection of HCV RNA in liver-biopsy specimens by RT-PCR HCV in extrahepatic region was reported like PBMCs, BM, CSF, spleen, pancreas, Therefore PBMCs are so beneficial, although gold standard is liver biopsy py

48 48