Hepatitis B Virus-Specific Antigens and Antibodies Used for Testing
Hepatitis B surface antigen (HBsAg): A protein on the surface of hepatitis B virus; it can be detected at high levels in serum during acute or chronic HBV infection. The presence of HBsAg indicates that a person is infected and 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 HBV infection. Anti-HBs also develops in a person who has been successfully vaccinated against hepatitis B.
Total hepatitis B core antibody (anti-HBc): This appears at the onset of symptoms in acute hepatitis B and generally persists for life. The presence of anti-HBc indicates previous or current infection with HBV in an undefined time frame.
IgM antibody to hepatitis B core antigen (IgM anti-HBc): Positivity indicates recent infection with HBV (less than 6 months). Its presence indicates acute infection.
SOURCE: CDC, 2009c.
United States could enhance HBV and HCV detection and help to close gaps in care, particularly in hard-to-reach populations.
Hepatitis B Virus Laboratory Testing Serologic markers can be used to identify the different phases of HBV infection (Box 5-6). The preferred laboratory test for detecting current HBV infection is for hepatitis B surface antigen (HBsAg), and the principal test for detecting recovery from HBV infection is for anti-HB surface antibody (anti-HBs). An alternative is to test initially for anti-HB core antibody (anti-HBc)—which is present during acute, chronic, and resolved HBV infection—and, if the result is positive, to conduct followup testing for HBsAg and anti-HBs. HBV markers can be misinterpreted by clinicians, and this can lead to clinical errors in patient evaluations, counseling, or treatment. For example, anti-HBc and anti-HBs can be misinterpreted as indicators of active infection (Weinbaum, 2008).