Hepatitis c infection, causes, treatment, and prevention

HEPATITIS C

History :

The first recognition of cases that caused neither by hepatitis A virus nor hepatitis B virus came in 1975.

This form of disease was called non –A-non –B hepatitis virus.

In 1989 this virus was identified, cloned and named hepatitis C virus (HCV)

Of those exposed to HCV, about 40% fully recovered because of their immune system that able to fight off the virus naturally.

The remainder whether they have symptoms or not, become chronic carriers.

Of these carriers, 20% develop cirrhosis and of those with cirrhosis, up to 20% develop liver cancer.

Egypt has the largest epidemic of hepatitis C virus(HCV) in the world.

Over 11000 individuals were tested and overall prevalence of people positive for HCV antibody was 14.7%.

In Egypt, the major route of exposure: Using injection therapy. Inadequate infection control practice. History of anti-schistosomal injection treatment. Using glass syringes. Dentistry.

Virology of HCV: Structure: HCV is small(55-66nm) enveloped positive single strand

RNA in the family Flaviviridae.

The core of genetic material(RNA) is surrounded by a protective shell of protein, encased in a lipid envelop of cellular origin.

Two viral glycoprotein, E1&E2 are embedded in the lipid envelope.

Genome :

Genotype : HCV classified into 6 genotypes, several subtypes and

species. 1,4 are less responsive to interferon-based treatment

than other genotypes 2,3,5,6. Duration of interferon-based therapy:1,4 48 weeks2,3 24 weeks Infection with one genotype not confers immunity

against others, infection may possible with two strains.

Natural history of HCV

Factors increasing the rate of HCV disease progression:

Age increased progression increased. Male is more rapid than female. Alcohols consumption. HIV co-infection. Fatty liver.

Symptoms : Joints pains. Sleep disturbance. Nausea. Depression. Fatigue. Flue-like symptoms.

Acute:Refers to the first months after infection, between 60-70% of people infected develop no symptoms during the acute phase. Symptoms : Decrease appetite. Fatigue. Abdominal pains. Itching. Fatigue Jaundice. Flue-like symptoms.

HCV detected in blood of infected person within 1 to 3 weeks of infection by PCR and antibodies of virus are detected within 3- 15 weeks.

4-15% clear virus during the acute phase ”spontaneous virus clearance” (HCV RNA clear).

Remaining 60-85% develop chronic hepatitis.

Chronic :When infection persisting for more than 6 months( asymptomatic). Symptoms of cirrhosis: Ascites “ accumulation of fluids in the abdomen”. Bruising and bleeding tendency, enlarged veins,

especially in stomach and esophagus. Jaundice and a syndrome of cognitive impairment.

Hepatic encephalopathy due to the accumulation of ammonia and other substances normally cleared by healthy liver.

• Blood testing

1. Hepatitis C antibody test

2. Hepatitis C PCR test to find virus in blood

• Liver function tests

HOW IS HEPATITIS C DIAGNOSED?

Normal AST, ALT, PT & albumin become abnormal if cirrhosis is developed

Liver biopsy is the best test to determine the amount of inflammation.

Serological blood tests used to detect antibodies of HCV.

HCV antibodies can be detected in 80% of patients within 15 weeks of exposure, in 90% within 5 months of exposure and in >97% within 6 months after exposure.

Seroreversion: means patients who have not yet developed antibodies.

All HCV nucleic acid tests (PCR&TMA) have the capacity to detect not only whether the virus is present but also to measure the amount of virus present in blood(viral load)

Important factor in determining the probability of response to interferon-based therapy but neither indicate disease severity nor the likelihood of disease progression.

In patient with confirmed HCV infection, genotype testing 1 generally recommended.

HCV genotype testing is used to determine the required length and potential response to interferon-based therapy.

HCV Diagnostic tests Liver function tests : ALT “ Alanine transferase” GPT “ glutamic pyruvate transaminase”

AST “ Aspartate transaminase” GOT “ Glutamate oxaloacetic transferase”Ratio of AST to ALT used to differentiate between causes of liver damage.

ALP “ Alkaline phosphatase”

Total bilirubin Bilirubin if increase, it cause jaundice and cause:

Pre hepatic: hemolytic anemia, internal hemorrhage.

Hepatic : problem with the liver, reflected as deficiencies in bilirubin metabolism(reduced hepatocyte uptake and secretion of bilirubin), cirrhosis and hepatic virus.

Post hepatic: obstruction of the bile ducts, reflected as deficiencies in bilirubin excretion.

Gamma glutamyl transferase “ GT” Enzyme-linked immunosorbent assay(ELISA):I. Sandwich assay:

II. Competitive binding assay:

Used when a matched pair of antibodies to the analytes doesn’t exist.

Ab+ fixed amount of labeled ligand+ variable amount of un labeled ligands incubate.

When conc. Of unlabeled increase, labeled ligand can bind to the antibody and the measured response decrease, lower the signal.

Antigen-down immunoassay“immunometric assay “

TMA( transcription mediated amplification):

Advantage of TMA:

Specificity ~ 99.5%.

Easy sample preparation.

Inherent design prevents contamination.

Efficient cost effective technology(high throughout 100 specimen/5hrs).

Liver biopsy

Treatment Alpha interferon: is a host protein that is made in

response to viral infection and has antiviral activity.

Another recombinant forms have been produced (alfa a2, alfa b2, consensus interferon).

Peginterferon: is an alfa interferon that is chemically modified by the addition of a large inert molecule of polyethylene glycol.

It is used instead of alfa interferon forms, which are mentioned in the previous slide.

Pegelation changes the uptake, distribution, and excretion of interferon, prolonging its half life time.

Ribavirin:

An oral antiviral agent that has activity against a broad range of viruses.

It has little effect on HCV, but adding it to interferon increases the sustained response rate by 2-3 folds.

Combination therapy leads to:

Rapid improvement in serum ALT levels.

Disappearance of detectable HCV RNA in up to 70% of patients.

A response is considered “sustained” if HCV RNA remains undetected for 6 months or more after stopping therapy.

Who should be treated?

Patients with HCV, HCV RNA , elevated serum aminotransferase.

evidence of chronic hepatitis on liver biopsy with no contraindications should offered combination therapy.

Patients with chronic HCV according to response to antiviral therapy.

Patients with cirrhosis if they don’t have signs of decompensations such as ascites, persistent jaundice or hepatic encephalopathy.

High rates Low rates• Women• Youth• Normal weight patients • Patients with lesser degree of

fibrosis on liver biopsy

Men Old Over weight patients

Who should not be treated? Contraindications to peginterferon therapy include: Severe depression Alcohol abuse Auto immune disease Bone marrow transplantation Marked anemia

New and future treatments: Drug affecting the immune

response against the virus Known as immune modifiers or

immunomodulators.

Alters the inflammatory response against liver cells infected with the virus.

Compounds of this type currently being tested in humans include:

Thymosin alpha1 dihydrocholoride

Specific agents against HCV proteins

One target for such drugs is HCV RNA genome.

Ribozyme (hepatazyme) can be designed to cleave HCV RNA genome in a region that the virus needs to survive.

Drugs that affect liver’s response to injury

Chronic HCV can lead to fibrosis and cirrhosis.

IP-501 (interneuron pharmaceuticals) is an orally administrated antifibrotic drug tested for treatment of alcoholic and HCV induced cirrhosis.

Re-grow a damaged liver When liver is damaged

beyond repair, the only hope is liver transplantation.

Liver stem cells can be isolated and grown into hepatocytes and bile duct cells in the laboratory.

Created by: Nada Sami, BSc in Microbiology & Chemistry and a postgraduate student.E-mail: nada_m78@yahoo.com