HEPATITIS C VIRUS Structure of presentation HCV epidemiology,viral dynamics,immunopathogenesis,diagnosis HCV renal disease, management HCV in CKD,CKD5D,CKD5T KDIGO guidelines • by the late 1970s it was apparent that HBV was not the only cause of "serum" hepatitis, • and that other "non-A-non-B" hepatitis viruses existed , which • could be transmitted by blood products to humans and chimpanzees • Houghton and colleagues cloned and expressed portions of a RNA virus from the plasma of an infected chimpanzee in 1989 • This virus, designated hepatitis C virus (HCV), is now known to be a major • cause of both transfusion-associated and sporadic non-A-non-B hepatitis • The persistent and indolent nature of HCV infection often • results in prolonged viremia in spite of a strong humoral immune response • To date, around 170–200 million individuals worldwide are estimated by the WHO to be chronically infected with HCV. THE VIRUS…… • Flavi virus • 50 nm particles • Nucleocapsid • RNA • Envelope • Circulates…. a. lipo-viro-particles b. Ig bound c. free virions THE GENOME RNA with 9600 nucleotides,encoding 3010 aminoacid polyprotein Single polypeptide Structural and non-structural 1. core – steatosis , IFN resistance 2. E1,E2 – cell entry 3. p7 – viral maturation & release 4. NS2 – autoprotease 5. NS3 – serine protease & helicase 6. NS4a – cofactor for 5 7. NS4b – membranous web for replication 8. NS5a – RNA binding , steatosis , 9. NS5b – RNA dep. RNA polymerase 10. IRES – internal ribosome entry site Significant nucleotide and amino acid heterogeneity is present throughout the HCV genome, with a well characterized hypervariable region in the E2 envelope glycoprotein domain . This has led to the recognition of at least six HCV subtypes based on differences in the nucleotide sequence for NS5 . Infection is followed by an incubation period of 6 to 12 weeks prior to the development of clinical hepatitis. In the majority of cases the hepatitis is mild and anicteric. Persistent viremia despite resolution of the acute hepatitis is seen in the majority of cases. many of these patients have persistent viremia despite minimal liver pathology, suggesting the presence of a "healthy― carrier state, at least 50% of patients develop chronic hepatitis, of which 20% progress to cirrhosis or chronic active hepatitis GENOTYPE… Genetically distinct groups of HCV isolates arisen during viral replication 35% variation esp. E1 E2 Distribution 1 --- 40 – 80% worldwide 1a – USA ; 1b – Europe 2 --- 10-40% worldwide 3 ---- India , Australia 4 --- Middle East , Africa 5 --- South Africa 6 --- Hongkong Do not influence severity Treatment response Genotype 3 – steatosis Genotype 1b – progressive post transplant disease QUASISPECIES… Closely related heterogeneous sequences in HCV in single infected person Mutation on replication E1E2 HVR Escape host immunity Resistance to treatment EPIDEMIOLOGY Seroprevelance Worldwide : 3% (Range 0.1 – 26%).Highest – Egypt India : 5% (Intermediate) Voluntary blood donor 0.6 – 0.8 % Gen.Population 1.8% Sex M: F 2.5 : 1.2 EPIDEMIOLOGY Epidemiology patterns Peak prevalence (Age) 30-50 yrs Recent source 1980-1990 IDU Peak prevalence > 50 yrs Remote acquisition 30 yrs ago Unsafe injections Folk medicine TRANSMISSION Percutaneous Blood transfusion Needle stick Non percutaneous Sexual Perinatal TRANSFUSION Initial Post Transfusion hepatitis : 85% Hep C Transfusion Hep C – 4% of Acute HCV Decreased after anti-HCV introduced in May 1990 Present risk - 0.01 – 0.001 % At risk Patient Requiring multiple transfusions Hemophilia Thallasemia Apollo chennai - HCV in blood donors : 3-5/ year (14,000 donations) HCV RNA screening IDU & OTHERS… Prevalence : 48 – 90% More than HIV & HBV Positive in 6 months Tattooing – 2- 24% Acupuncture HEMODIALYSIS Anti HCV prevalence: 10- 20% Underestimate (4-15%) Duration on HD Annual Risk : 0.15% (HD) & 0.03% (CAPD) Chr.HCV : 70-90% At Apollo HCV+ve on HD – 11/140 HCV in CKD on HD Prevalence – 1. Developed nations – 7 – 40% 2. Developing nations– 16 – 80% 3. India – 12 – 40% ( Saha etal 2001) 4. Apollo – 12% Risk factors – 1. Duration on HD 2. Local prevalence 3. Blood transfusions 4. Nosocomial transmission April 15, 2011 HCV and Renal Disease Nosocomial Transmission… Breach of standard infection control precautions 1. Hand wash , glove change Okuda et al ; Arenas et al 2. Multi-dose vials 3. Spillage Dialysis internal circuits minor contributor DOPPS – Isolation does not protect CDC – 1. No isolation 2. No dedicated machines Belgian study – 0% transmission by standard precautions only Slow seroconversion ( 5 months) Regular EIA / NAT , ALT / AST April 15, 2011 HCV and Renal Disease NOSOCOMIAL Health workers Needle stick : 0-4% by anti-HCV 10% by PCR Overall seroprevelance is as gen.population Risks of transmission < HBV,HIV HCW patient 0.014% Patient HCW 2- 10% NON-PERCUTANEOUS Sexual – controversial More common in male homosexuals Associated risk factors RNA levels in semen low HCV in spouse 3% PERINATAL TRANSMISSION Risk upto 10% No difference in CS vs. vaginal Increased risk RNA +ve Increased RNA levels HIV-HCV decreased with HAART Not transmitted by breast feed Passive transfusion of Anti HCV Anti HCV upto 18 months SPORADIC HCV Upto 30- 40% of cases Occult / unidentified percutaneous Sharing of hygiene items Forgotten risks, Transfusion Multi-dose vials Cocaine snorting PATHOGENESIS Viral Human Environmental Main sites : Hepatocyte Other : Mononuclear : Dendritic cells IMMUNE MEDIATED MECHANISM Humoral Response CMI CD4 CD8 - liver infiltrating NK CMI RESPONSE • CD4,CD8, NK • Protective and Destructive • More in Acute cases • Activated by antigen presentation • CD4+ (polyclonal) TH1 TH2 • TH1 IFN + IL2 NK cells & CTLs • TH2 IL4 + IL10 decrease TH1 • TH1 viral clearance VIRAL PERSISTENCE Quasi-species nature Immune evasion Inadequate innate immunity Insufficient adaptive response Re-infection with different strain PATHOGENESIS.. Pathogenesis - Viral - Host - Environmental VIRAL Direct cytopathic effect Viral Protein Viral particles Steatosis 30 – 70% C, NS5a viral proteins Genotype 3 Activation of lipid peroxidation Increased RNA Increased Steatosis Contribution of fibrosis - Oxidative stress - Hyperinsulinemia CMI IN PATHOGENESIS…… CD8+ Polyclonal activation Increased in infected liver IFN gamma Hepatocyte cytolysis Inhibit multiplication HUMORAL IMMUNITY…… Ig to viral proteins Non neutralising 4 – 8 weeks of infection Marker of infection Lymphoid aggregates Extra hepatic manifestations B cell ++ polyclonal Ig auto Ig CD5 ++ rheumatoid factor cryoglobulinemia ( Ig + RF ) SUMMARY OF PATHOGENESIS Viralreplication & persistence Inhibition of innate immunity Balance between CD4 & CD8 hepatocyte damage Poor response in chronic disease Viral cytopathic effect Antibodies --- 1. diagnostic 2. extra hepatic manifestations EXTRAHEPATIC MANIFESTATIONS Mixed Cryoglobulinemia MPGN Porphyria cutanea tarda NHL Leucocytoclastic vasculitis Focal lymphocytic sialadenitis Lichen planus DM Rheumatoid arthritis Thyroid disease Non specific antibodies ANA – 20% , ASMA -20% , anti LKM – 5% , cryoglobulins-40% MIXED CRYOGLOBULINEMIA • Circulating Igs precipitating at < 37c • Vasculitis by deposition of cryoprecipitate in small vessels • IgG, IgM RF, anti HCV, HCV RNA , LDL • IgM RF from liver • B cell activation by E1 E2 – CD81 interaction • 50 -90% EMC – HCV + • 60% HCV pts. - MC (30%asymptomatic) • Purpurae, arthralgias , weakness • Peripheral neuropathy • Raynaud’s phenomenon • MPGN – nephrotic syndrome liver disease occult • Antiviral therapy EXTRAHEPATIC MANIFESTATIONS…. B cell NHL – HCV 15% lymphotropism & clonal expansion Sialadenitis – 10% patients Diabetes Mellitus – steatosis , insulin resistance, IN A NUTSHELL…. • A RNA virus with hepatotropism • Widely distributed with distinct genotypes • Evades immune system • Pathogenesis by steatosis fibrogenesis & host immunity • Transmission by parenteral route • Acute hepatitis rarely recognised • High rate of chronicity • Multiple influences • Extrahepatic manifestations • HCC Mesangio proliferative gn igA Fibrillary and immunotactoid gn Diffuse endocapillary proliferative gn MGN MPGN Renal vasculitis cryoglobulinemic HCV induced renal disease EMC type II ( 50% of HCV ; 1% symptomatic) MPGN type I ( with or without MC) Membranous glomerulonephritis Pathology - Deposition of HCV RNA – Ig complexes OLT – intraop renal biopsy – 25 – 30% GN Proteinuria , Microscopic hematuria Liver disese may be occult Melzer Franklin triad (EMC) Weakness , Arthralgia , Purpurae Elevated Cryocrit ,Rheumatoid factor ; Decreased C4 Test annually 1. hematuria 2. proteinuria 3. GFR Renal biopsy April 15, 2011 HCV and Renal Disease Diagnostic tools… Serological 1. Enzyme Immunoassay (EIA) 2. Recombinant Antigen Immunoblot Assay (RIBA) HCV RNA detection a. Qualitative b. Quantitative Methods 1. PCR 2. TMA (Transcription mediated amplification) HCV Genotyping Liver biopsy Serological…… Detect Igs against viral proteins EIA 3rd generation NS3 , NS4 , NS5 Positive at 7 – 8 weeks Sensitivity – 97% RIBA for clarifying false positives Negative anti- HCV in HCV infection 1. immunosuppressed 2. CKD , on HD 3. Acute HCV The original first generation enzyme immunoassay (EIA-l), which measured antibodies to the nonstructural Cl00-3 antigen (coded by the NS4 domain), lacked sensitivity and specificity, and was undetectable in 10 to 25% of patients with chronic HCV viremia and falsely present in both healthy individuals and patients with chronic autoimmune hepatitis The second generation enzyme immunoassay (EIA-2) measures antibodies to recombinant core and NS3 antigens in addition to that coded by NS4, and has greatly improved sensitivity (— 95%) and specificity. A supplemental serologic assay, the recombinant immunoblot assay (RIBA II test), measures antibody to four HCV antigens (the nonstructural antigens 5-1-1, C100-3, and C33, and the core antigen C22), and has comparable sensitivity and slightly more specificity than the EIA-2 test The most definitive test for diagnosing active HCV infection is the reverse transcription polymerase chain reaction (RT-PCR), which measures the presence of viral RNA in patient serum and hence determines potential infectivity The detection of anti-HCV antibodies is based on the use of third-generation EIA that detects antibodies directed against various HCV epitope RIBA has become obsolete because of this In the near future, fourth-generation tests will be available, allowing the simultaneous detection of HCV antibodies and HCV core protein. In the relevant published studies, the sensitivity of EIA varied from 53 to 100% and the specificity from 85 to 100%, with pooled sensitivity and specificity of 75 and 95%, respectively RNA testing Qualitative 1. high sensitivity 96- 100% 2. PCR / TMA 3. lower limit – 50iu / 5iu 4. confirm clearance 5. special situations Quantitative 1. RT - PCR / branched DNA 2. closed tube systems 3. Amplicor – PCR - 3 copies – 1 unit 4. Versant – TMA – 5 copies = 1 unit Indications 1. anti HCV positive 2. antiviral treatment monitoring 3. immunocompromised RNA analysis… Genotyping…. 1. reverse hybridisation by line probe assay 2. failure – 0.3% 3. duration of treatment 4. response to treatment Histopathology Degree of inflammation – grade Extent of fibrosis – stage Characteristic features 1. steatosis ( micro or macrovesicular) 2. lymphoid aggregates 3. bile ductular damage Metavir and Knodell Ishak staging systems Fibrosis – prognosis & treatment response Metavir – fibrosis 0 – 4 grade – 0 -4 Knodell Ishak – fibrosis 0 – 6 Significant fibrosis - Metavir ≥2 Knodell Ishak ≥3 Liver biopsy - problems….. Inter observer variation – 60 – 90% Variability within liver Specimen size Complications – 1. pain – 20% 2. hemorrhage – 0.5% 3. mortality – 0.1% Sampling error – 10 – 40% 1. small size 2. less than 11 portal tracts analysed Typically, a platelet count o50 000 and an INR >1.5 are regarded as contraindications to blind percutaneous liver biopsy However, there is a controversy in recent medical literature about whether any platelet count level or INR derangement truly separates out those patients with liver disease most likely to bleed after liver biopsy. A study performed in the early 1980s in 200 patients undergoing laparoscopic liver biopsy with direct visualization of the site failed to establish any relationship between duration and extent of bleeding and prothrombin times,platelet count, or whole clot time. a systematic review of bleeding, including that associated with liverbiopsy, also failed to establish a relationship between risk and conventional tests of coagulation Noninvasive staging FIBROSCAN transient elastography assess liver stiffness evaluates larger liver volume better correlate with higher stage problems – 1. obese 2. cannot differentiate steatosis Other markers FIBROTEST- α2-macroglobulin , α2-globulin , gamma globulin , GGTP , bilirubin sens. 75% & spec. 85% for Metavir >2 improved with Fibroscan ACTITEST - Fibrotest + ALT APRI – AST – Platelet count ratio Ser. Hyaluronate levels Collagen based panels ALT levels Mildly elevated only 10 fold increase – sig. necrosis 30% normal ALT 17% - levels fluctuate to normal 30 – 40% - occ. elevations only THANK U…. MORE TO FOLLOW………….