Tiêu đề Hepatitis marker.pdf ✅

■ ■ ■ ■ Interpretation of Hepatitis B Serologic Test Results Hepatitis B serologic testing involves measurement of several hepatitis B virus (HBV)-specifi c antigens and antibodies. Different serologic “markers” or combinations of markers are used to identify different phases of HBV infection and to determine whether a patient has acute or chronic HBV infection, is immune to HBV as a result of prior infection or vaccination, or is susceptible to infection. Hepatitis B surface antigen (HBsAg): A protein on the surface of hepatitis B virus; it can be detected in high levels in serum during acute or chronic hepatitis B virus infection. The presence of HBsAg indicates that the person is infectious. The body normally produces antibodies to HBsAg as part of the normal immune response to infection. HBsAg is the antigen used to make hepatitis B vaccine. Hepatitis B surface antibody (anti-HBs): The presence of anti-HBs is generally interpreted as indicating recovery and immunity from hepatitis B virus infection. Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B. Total hepatitis B core antibody (anti-HBc): Appears at the onset of symptoms in acute hepatitis B and persists for life. The presence of anti-HBc indicates previous or ongoing infection with hepatitis B virus in an undefi ned time frame. IgM antibody to hepatitis B core antigen (IgM anti-HBc): Positivity indicates recent infection with hepatitis B virus (<6 mos). Its presence indicates acute infection. Tests Results Interpretation HBsAg negative Susceptible anti-HBc negative anti-HBs negative HBsAg negative Immune due to natural infection anti-HBc positive anti-HBs positive HBsAg negative Immune due to hepatitis B vaccination anti-HBc negative anti-HBs positive HBsAg positive Acutely infected anti-HBc positive IgM anti-HBc positive anti-HBs negative HBsAg positive Chronically infected anti-HBc positive IgM anti-HBc negative anti-HBs negative HBsAg negative Interpretation unclear; four possibilities: anti-HBc positive 1. Resolved infection (most common) anti-HBs negative 2. False-positive anti-HBc, thus susceptible 3. “Low level” chronic infection 4. Resolving acute infection Adapted from: A Comprehensive Immunization Strategy to Eliminate Transmission of Hepatitis B Virus Infection in the United States: Recommendations of the Advisory Committee on Immunization Practices. Part I: Immunization of Infants, Children, and Adolescents. MMWR 2005;54(No. RR-16). DEPARTMENT OF HEALTH & HUMAN SERVICES Centers for Disease Control and Prevention Division of Viral Hepatitis www.cdc.gov/hepatitis
Hepatitis B - virology • DNA virus • class Hepadnaviridae • Transmission • Sexual contact • Injecting drug use or other percutaneous exposure i.e. tatoos • Perinatal transmission • There are two possible outcomes following hepatitis B infection • 1) clearance of the hepatitis B virus • 2) Chronic hepatitis B infection
Hepatitis B – clinical features • Incubation period 45-180 days (mean 60-90 days) • Clinical illness associated with acute infection is age- dependent: • Jaundice occurs in <10% of children less than 5 years of age • Jaundice occurs in 30%-50% of older children and adults. • Most acute HBV infections in adults result in complete recovery with clearance of HBsAg from the blood, production of anti-HBs, and immunity from future infection. • ~30%-90% of young children and 2%-10% of adults develop chronic infection (“carrier state”) • Persons with chronic HBV infection are often asymptomatic: • high risk for developing cirrhosis or liver cancer.
Hepatitis B serological markers • Hepatitis B surface antigen (HBsAg) • This is a protein on the surface of the hepatitis B virus (HBV); it can be detected in the serum during acute or chronic HBV infection. • The presence of HBsAg indicates that the person has hepatitis B infection. • HBsAg is the antigen used to make hepatitis B vaccine. • Total hepatitis B core antibody (anti-HBc) • Appears at the onset of symptoms in acute hepatitis B infection and persists for life. • The presence of anti-HBc indicates previous or ongoing infection with HBV. • IgM antibody to hepatitis B core antigen (IgM anti-HBc) • Its presence usually indicates acute (<6 months) as opposed to chronic hepatitis B infection. • Can also be found during viral reactivations • Hepatitis B e antigen (HBeAg) • A product of the nucleocapsid (envelope) gene of the hepatitis B virus that is found in serum during acute and chronic hepatitis B infection. • Its presence indicates that the virus is replicating and the infected person has high levels of HBV. However patients that are HBeAg negative may also have high levels of HBV. • Hepatitis B e antibody (HBeAb or anti-HBe) • Spontaneous conversion from e antigen to e antibody (a change known as “e” seroconversion) is a predictor of long- term clearance of HBV in patients undergoing antiviral therapy and indicates lower levels of HBV. • Spontaneous “e” seroconversion also occurs in natural infection • Hepatitis B surface antibody (anti-HBs) • The presence of anti-HBs is generally interpreted as indicating recovery and immunity from HBV infection. • Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B.