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The tests, called assays, for detection of hepatitis B virus infection involve serum or blood tests that detect either viral antigens (proteins produced by the virus) or antibodies produced by the host. Interpretation of these assays is complex.

The hepatitis B surface antigen (HBsAg) is most frequently used to screen for the presence of this infection. It is the first detectable viral antigen to appear during infection. However, early in an infection, this antigen may not be present and it may be undetectable later in the infection as it is being cleared by the host. The infectious virion contains an inner “core particle” enclosing viral genome. The icosahedral core particle is made of 180 or 240 copies of core protein, alternatively known as hepatitis B core antigen, or HBcAg. During this ‘window’ in which the host remains infected but is successfully clearing the virus, IgM antibodies to the hepatitis B core antigen (anti-HBc IgM) may be the only serological evidence of disease.

Shortly after the appearance of the HBsAg, another antigen named as the hepatitis B e antigen (HBeAg) will appear. Traditionally, the presence of HBeAg in a host’s serum is associated with much higher rates of viral replication and enhanced infectivity; however, variants of the hepatitis B virus do not produce the ‘e’ antigen, so this rule does not always hold true. During the natural course of an infection, the HBeAg may be cleared, and antibodies to the ‘e’ antigen (anti-HBe) will arise immediately afterwards. This conversion is usually associated with a dramatic decline in viral replication.

If the host is able to clear the infection, eventually the HBsAg will become undetectable and will be followed by IgG antibodies to the hepatitis B surface antigen and core antigen, (anti-HBs and anti HBc IgG). The time between the removal of the HBsAg and the appearance of anti-HBs is called the window period. A person negative for HBsAg but positive for anti-HBs has either cleared an infection or has been vaccinated previously.

Individuals who remain HBsAg positive for at least six months are considered to be hepatitis B carriers. Carriers of the virus may have chronic hepatitis B, which would be reflected by elevated serum alanine aminotransferase levels and inflammation of the liver, as revealed by biopsy. Carriers who have seroconverted to HBeAg negative status, particularly those who acquired the infection as adults, have very little viral multiplication and hence may be at little risk of long-term complications or of transmitting infection to others.

PCR tests have been developed to detect and measure the amount of HBV DNA, called the viral load, in clinical specimens. These tests are used to assess a person’s infection status and to monitor treatment. Individuals with high viral loads, characteristically have ground glass hepatocytes on biopsy.

People who may want to talk to their doctors about screening for hepatitis B infection include

Hepatitis B Tests and Diagnosis:

1.Pregnant women
2.People who receive kidney dialysis
3.People who have one or more parents from an area of the world where hepatitis B is more common
4.Men who have sex with men
5.Inmates
6.Injection drug users
7.Immigrants, including internationally adopted children, from areas of the world where hepatitis B is more common, including Asia, the Pacific Islands, Africa and Eastern Europe
8.HIV-positive people
9.Babies born to women with hepatitis B
10.Anyone with an unexplained, abnormal liver enzyme test
11.Anyone who has had sex with a person who has hepatitis B infection
12.Anyone who lives with a person who has hepatitis B infection

Hepatitis B is diagnosed from the results of specific HBV blood tests (serologies) that reflect the various components of the HBV. The diagnosis is made on the basis of a blood sample which will demonstrate antibodies against hepatitis B, or hepatitis B components in the patient’s blood. The blood sample can demonstrate the presence of several different viral

components. All patients with chronic infections have the viral component called HBsAg. When HBsAg is present, the infectiousness of the disease is at its highest and in the long run, those patients are at increased risk of developing complications. A blood test for liver function can determine the severity of the disease – the extent to which the liver is affected by the virus. In cases of chronic type B hepatitis, the severity of the disease can be determined by a tissue sample from the liver.

Hepatitis B Tests:

Antibody to Hepatitis B Core Antigen (anti-HBc):Although this test identifies people who have a chronic infection, the results can sometimes be ambiguous. If you test positive for hepatitis B core antibodies, you may have a chronic infection that you can transmit to others. But you also may be recovering from an acute infection or have a slight immunity to HBV that can’t otherwise be detected. How this test is interpreted often depends on the results of the other two tests. When the results are uncertain, you may need to repeat all three tests.

2.Antibody to Hepatitis B Surface Antigen (anti-HBs):A positive result on this test means you have antibodies to HBV. This may be due to a prior HBV infection from which you’ve recovered. Or, you may already have been vaccinated. In either case, you can’t infect others or become infected yourself because you’re protected by the vaccine or your own natural immunity.

3.Hepatitis B Surface Antigen (HBsAg): Hepatitis B surface antigen is the outer surface of the virus. Testing positive for this antigen means you can easily pass the virus to others. A negative test means you’re not currently infected.

4.Tests to measure liver function. Liver function tests may gauge the amount of damage that has occurred in your liver cells.

5.A test to determine how much HBV DNA is in your blood. The hepatitis B DNA test detects parts of HBV DNA in your blood, indicating how much virus is present (viral load). Assessing your viral load can help monitor how well antiviral therapy is working.

6.A test to determine how likely you are to spread HBV to others. The E antigen blood test looks for the presence of a protein secreted by HBV-infected cells. A positive result means you have high levels of the virus in your blood and can easily infect others. If the test is negative, you have lower blood levels of HBV and are less likely to spread the infection.

Active infection is indicated by the presence of hepatitis B surface antigen (HBsAg) in serum.

Acute hepatitis B is diagnosed in patients who are positive for HBsAg and have evidence of disturbed liver function, symptoms and a risk history suggesting recent infection. Repeatedly positive HBsAg over a 6 month period, in the absence of acute symptoms or risk history to suggest recent infection, indicates a chronic carrier state.

A person who has positive hepatitis B surface antibody (HBsAb) and negative HBsAg is immune and should not be further tested for hepatitis B. Positive HBsAb with negative core antibody (HBcAb) is usually indicative of vaccination.