1. Biochemistry of Hepatitis C
PHM Fall 2015
Coordinator: Dr. Jeffrey Henderson
Instructor: Dr. David Hampson
Biochemistry of Hepatitis C
Lisa Liu, Anastasia Pimenova, Brittany Nicholls

2. Hepatitis C liver disease caused by the Hepatitis C virus (HCV)1
liver disease caused by the Hepatitis C virus (HCV)
causes both acute and chronic infection
HCV caused by blood borne virus
blood-blood transmission
million people globally have chronic hepatitis
~240,000 individuals are infected in Canada
current drug treatment available
no vaccine available
2nd point:
transmission by: inadequate sterilization of medical equipment and transfusion of unscreened blood and blood products
3rd point: epidemiology
highest prevelance in central+east asia, north africa and middle east
Additionally, HCV has enormous genetic diversity in
infected hosts, existing in blood as a swarm of related
quasispecies. This diversity is a result of the error-prone
viral polymerase, and fast viral replication enables rapid
adaptation to host antibody responses, cellular immune
responses, and antiviral drugs
current drug treatments use peginterferon alfa (act to induce antiviral response) and oral ribacirin (stop viral synthesis and mRNA capping)
this combination can read to a sustained virological response (clinically seen as aviremia ; lack of virus in blood plasma)

3. Prognosis 1 fibrosis: first stage of liver scarring
cirrhosis- scar tissue builds up and takes over most of liver
are not health /functional hepatocyte cells
time and accumulation of scarring results in cirrhosis (20-25 years)

4. Effects of Hepatitis C 1,2 gallbladder impairment
Li Y, Yamane D, Masaki T, Lemon SM. The yin and yang of hepatitis C: synthesis and decay of hepatitis C virus RNA. Nat Rev Microbiol. 2015;13(9):
hCV virus damage liver cells -- leading to scarring and higher prevelance of hepatocytes developing into cancer cells
hypothroidism: the damage and subsequent drugs used to treat Hep C can trigger autoimmune responses which in turn damages the thyroid tissue and its funciton
the lack of normal blood filtering by the liver results in buildup of blood and results in blood vessel diation (as seen in portal hypertension)
the lack of normal blood flow and the lack of the liver to properly filter blood also results in anemia (the inability of liver the recycle RBCs\0
as mentioned above, the lack of adequate blood flow through the liver also affect the systemic circuit in neighbouring organs such as the stocmach
livers cannot produce bile as well, lack of proper digestion of fatty foods

5. single stranded RNA lipid and protein-enveloped virus of 9.6kb
HCV structure 3
single stranded RNA lipid and protein-enveloped virus of 9.6kb

6. HCV Genomic/Proteomic Structure3
RNA codes for amino acid polyprotein
3 structural proteins make the envelope: capsid and envelope glycoproteins E1/E2
non structural proteins for genome replication: NS2, NS3, NS4A, NS4B, NS5A, NS5B
5’ end of RNA codes for structural proteins and the rest codes for non structural

7. Entry into Liver Endothelium4
HCV Capture: 2 options
Via L-SIGN. Transcellular transport.
Via DC-SIGN. Paracellular transport.
Lyu J, Imachi H, Fukunaga K, Yoshimoto T, Zhang H, Murao K. Roles of lipoprotein receptors in the entry of hepatitis C virus. World J Hepatol. 2015;7(24):
DC SIGN: dendritic cells. Attaches to DC-SIGN
L-SIGN: L stands for lectins which are a class of proteins which bind to sugar residues. In the case of HCV, L-SIGN binds to mannose found in glycoproteins in the capsid.

8. Entry into Hepatocyte 3 steps: Interaction with LDLR4
3 steps:
Interaction with LDLR
Binding to SR-BI and CD81
Use of CLDN-1 and OCLN to result in clathrin-mediated endocytosis
Roles of lipoprotein receptors in the entry of hepatitis C virus
LDLR: low density lipoprotein receptor. Unknown mechanism.
SR-BI: scavenger receptor class B, type 1. Mediates uptake of high density lipoprotein which is found in the E2 structural protein.
CLDN-1 and OCLN: CLDN-1 interacts with CD81 which assists in virus entry. OCLN interacts with E2 structural protein.

9. HCV infection overview5
after capsid uncoating, RNA is translated into protein at the rough ER
proteins encoded by HCV make more HCV RNA
structural proteins (capsid, E1, E2) are packaged and assembled in the Golgi
capsid is assembled with RNA inside and expelled by exocytosis
virus can now infect other hepatocytes
Tan S. Hepatitis C Viruses, Genomes and Molecular Biology. Horizon Scientific Press; 2006.

10. Replication of HCV: Translation5
5’UTR has internal ribosome entry site (IRES) that facilitates hepatocytic 40s ribosome subunit binding
60s subunit recruited, can now translate
RNA enters cell when capsd fuses with hepatocyte membrane

11. Role of HCV protein segments5
Role of HCV protein segments
HCV polyprotein cleaved by hepatocyte proteases into:
NS2, NS3 and NS4A: HCV proteases that cleave the polyprotein
NS3: also acts as helicase, unwinds HCV RNA for replication
NS5B: RNA polymerase, makes +/- HCV RNA strands
NS4B: creates vesicles for viral assembly

12. Damage to hepatocytes HCV is not directly cytopathic to hepatocytes6
HCV is not directly cytopathic to hepatocytes
Immune mediated
subvert activity of NK cells, and CD4+ and CD8+ T cells
HCV-specific T cells become unresponsive and disappear
Many pathways are proposed and involve the innate and adaptive immune responses
Spengler U, Nattermann J. Immunopathogenesis in hepatitis C virus cirrhosis. Clin Sci. 2007;112(3):
HCV and fibrosis (scarring)

13. Damage to Hepatocytes via Cytokines6
HCV core proteins and NS3 proteins trigger monocytes and mast cells to release cytokines
IL1, IL6, IL8, TNF
Due to impaired immune system, cytokines are continuously released
lead to hepatocyte damage, fibrogenesis and cirrhosis via inflammation
Spengler U, Nattermann J. Immunopathogenesis in hepatitis C virus cirrhosis. Clin Sci. 2007;112(3):

14. Summary Slide
Single stranded RNA lipid and protein-enveloped virus of 9.6kb
Affects liver and causes liver damage
Structural proteins: E1, E2 and capsid, Non-structural proteins:NS2, NS3, NS4A, NS4B, NS5A, NS5B
Entry via clathrin coated endocytosis
3 step process using LDLR, SR-BI, CD81, CLDN1, OCLN
Replication via non-structural proteins
Damage to liver via adaptive and innate immune responses
cytokines cause inflammation and cell death

15. References
Webster DP, Klenerman P, Dusheiko GM. Hepatitis C. Lancet ;385(9973):
Li Y, Yamane D, Masaki T, Lemon SM. The yin and yang of hepatitis C: synthesis and decay of hepatitis C virus RNA. Nat Rev Microbiol. 2015;13(9):
Budkowska A. Mechanism of cell infection with hepatitis C virus (HCV)--a new paradigm in virus-cell interaction. Pol J Microbiol. 2009;58(2):93-8.
Lyu J, Imachi H, Fukunaga K, Yoshimoto T, Zhang H, Murao K. Roles of lipoprotein receptors in the entry of hepatitis C virus. World J Hepatol. 2015;7(24):
Tan S. Hepatitis C Viruses, Genomes and Molecular Biology. Horizon Scientific Press; 2006.
Spengler U, Nattermann J. Immunopathogenesis in hepatitis C virus cirrhosis. Clin Sci. 2007;112(3):