HEPATITIS B MARKERS AND VACCINE PBL 21 TUTOR : PROF MOHAMED A. EL-FARRASH

OBJECTIVES DEFINITION ? MARKERS OF HEPATITIS B ? HBV SURFACE ANTIGEN (HBsAg) HBV e ANTIGEN (HBeAg) SURFACE ANTIBODY (Anti-HBs) e ANTIBODY (Anti-HBe) CORE ANTIBODY (Anti HBc IgM) CORE ANTIBODY (Anti HBc IgG) VACCINE FOR HEPATITIS B ? WHAT IT IS MADE OF? GIVEN TO WHOM? WHAT TO DO BEFORE & AFTER VACCINATION? FATE OF VACCINATION? OBJECTIVES

DEFINITION ? Hepatitis : inflammation of liver; presence of inflammatory cells in organ tissue. Type : Hepadnaviridae (DNA Virus). Hepatitis B serological markers : A generic term referring to hepatitis B antigens and antibodies to these antigens. Vaccine : administration of antigenic material to stimulate an individual's immune system to develop adaptive immunity to a pathogen.

MARKERS OF HEPATITIS B ?

HBV surface antigen (HBsAg) Is the first antigen to show up on a test when someone becomes initially infected with HBV. HBsAg may be present before symptoms appear. If someone has the surface antigen they are able to infect others. When the antigen is in the body longer than 6 months then a person has chronic HBV infection.

HBV e antigen (HBeAg) The second antigen that appears as a result of the virus replicating in the body. If someone has the “e” antigen it means that HBV is actively infecting and replicating in liver cells. The presence of the “e” antigen also means that the person’s blood and bodily fluids are very infectious. This test determines how contagious the patient is and may differentiate chronic replicative from chronic non-replicative states.

Surface antibody (anti-HBs) Is produced to fight HBV. If the body produces large enough quantities, it can clear HBV from the body called a resolved infection. It remains detectable for life and is not found in chronic carriers. It is the antibody present after successful HBV vaccine.

E antibody (Anti-HBe) Is produced when the body responds to infection by producing antibodies to the “e” antigen. Generally, when the “e” antibody is found it means that the body is fighting HBV. Its presence cannot be used to predict the outcome of a chronic infection.

Core antibody Core antibody ( Anti HBc IgG) (Anti HBc IgM) Appear shortly after the onset of symptoms of hepatitis B infection and soon after the appearance of hepatitis B surface antigen (HBsAg). Marker of acute infection, which rises early (within 2-4 weeks) of HBV infection and slowly disappears. ↓ levels of Anti HBc IgM indicate resolving infection. Rises soon after IgM, and remains present for life in both chronic carriers as well as those who clear infection. It rises 4-6 months after infection and persists for life. Partially protective anti-HBc antibody levels can be induced by recombinant vaccination, but are short-lived.

Markers in Acute HBV infection

Markers in Chronic infection

VACCINE FOR HEPATITIS B ?

VACCINATION FOR HEPATITIS B The first hepatitis B vaccine to become available commercially in 1982 consisted of HBsAg purified from the plasma of persons with chronic HBV infection. Now been replaced by recombinant vaccines that are free of any concerns associated with human blood products. HBsAg gene has been inserted into yeast and mammalian cells by means of appropriate expression vectors. Antigen expressed in several species of yeast, namely Saccharomyces cerevisiae, Pichia pastoris and Hansenula polymorpha, and Chinese hamster ovary (CHO) cells

Administration of 3 doses induces protective level of antibodies in 95% of vaccine recipients.

GIVEN TO WHOM ? Sexually active homosexual and bisexual males, including those with HIV infection. Persons who may be exposed to the virus by means of blood such as healthcare workers Sexual contacts of HBV carriers. Persons in areas with high risk of HBV infection. Persons who shared the use of illegal injection drugs. Infants of HBV carrier mothers. All newborn infants are now vaccinated.

vaccines: Recombinant HBsAg

WHAT TO DO BEFORE VACCINATION? Pre-vaccination serologic screening for previous infection is not indicated for healthcare providers. Screening may exclude persons with high titers of HBsAb as they are already immune. Neworn babies are not screened before vaccination

WHAT TO DO AFTER VACCINATION? After 3-4 weeks from the last dose of the vaccine, vaccinated person should be tested for HBsAb. In health care workers the protective titer should be above 100 mIU/ml of HBs Ab while in usual persons it is 10 mIU/ml. Booster doses (after the 3 doses course) are not necessary, and periodic serologic testing to monitor antibody titer after completion of the vaccine series is not recommended.

FATE OF UNSUCCESSFUL VACCINATION? A "vaccine non-responder" is a person who does not develop protective surface antibodies after completing two full series of the hepatitis B vaccine and for whom an acute or chronic hepatitis B infection has been ruled out. Although the majority of persons vaccinated against hepatitis B successfully respond to vaccination, an estimated 5-15% of persons may not respond.

It is possible that a person who does not respond to the vaccine may already be infected with hepatitis B. Therefore, testing for the presence of the virus (HBsAg) is recommended before diagnosing a person as a "vaccine non-responder". You would be wise to seek a check on your hepatitis B status. It is possible that you have been exposed to past infection, and this would be confirmed if your serum is Anti-HB core positive.

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