Recombinant ImmunoBlot Assay (RIBA) Test for HCV

The Recombinant ImmunoBlot Assay (RIBA) is a blood test that detects antibodies to the hepatitis C virus (HCV). It was used for many years as a secondary confirmation test if a first-line screening test for HCV (called the ELISA hepatitis C antibody test) came back positive or indeterminant. However, as other tests became more sensitive and accurate, it was discontinued for detecting HCV and other tests are now used instead.

Hepatitis C virus
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How the Test Works

When you have been exposed to hepatitis C, your body makes antibodies to the virus. These antibodies circulate in your bloodstream for many years, perhaps even throughout your lifetime. The RIBA HCV test was used to detect those antibodies.

Who Is Tested?

The virus is spread through direct contact with infected blood. Routine screening is done for people who are at higher risk of contracting it, such as those who use injection drugs and baby boomers who were born between 1945 and 1965.

Your blood will also be tested if you donate blood, as blood transfusions can transmit the hepatitis C virus. If you submit donor blood that tests positive for HCV antibodies, it will be rejected and you will be permanently banned from donating blood in order to protect people who receive blood transfusions.

Use of the RIBA HCV Test

If you are looking at older laboratory results in your medical record, you may see the Hepatitis C RIBA test reported. It may be called "HCV RIBA" or it may be spelled out as "Recombinant ImmunoBlot Assay." Again, it would have been ordered because your original ELISA screening test for the hepatitis C antibody (anti-HCV) was either positive or indeterminant.

In past years, the first ELISA tests that were performed to look for the hepatitis C antibody often had false positives, meaning that they showed a positive result when you actually didn't have any hepatitis C antibody. As a result, it was necessary to double-check every positive result with a secondary or confirmation test that was more specific.

The RIBA HCV test is more specific than the ELISA hepatitis C antibody test. But it's also an additional expense, so it was performed only if the ELISA anti-HCV test showed a positive result.

Positive and Negative Results

If the RIBA HCV test also showed a positive result, this confirmed that you had hepatitis C antibodies and had been exposed to HCV. The next step was to test for HCV RNA (viral load) to see if the hepatitis C virus was still present in your body.

If, however, the RIBA test came back negative, your doctor may have ordered other tests to ensure that you didn't have HCV, depending on whether you were showing signs of the disease or you had a condition that might affect the accuracy of the tests

Recombinant ImmunoBlot Assay Testing Discontinued

The 2013 Guidelines from the Centers for Disease Control and Prevention note that the RIBA HCV test has been discontinued. The manufacturer, Novartis Vaccines, and Diagnostics, no longer offers it for use. Instead of using RIBA as the confirmatory test, clinicians now use a test that detects HCV viremia (the presence of HCV in the blood).

RIBA Test in Other Settings

The RIBA test may still be in use in other situations, such as in blood banking. Donor blood samples are screened for HCV, and a positive sample may be retested to confirm that it shows the hepatitis C virus. RIBA has been commonly used as that confirmation test, but as technology evolves it may be replaced with other tests.

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Article Sources
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  1. US Department of Veterans Affairs. Viral Hepatitis and Liver Disease Laboratory Tests.

  2. Safi MA. Hepatitis C: an Overview of Various Laboratory Assays with their Mode of Diagnostic Cooperation. Clin Lab. 2017;63(5):855-865. doi: 10.7754/Clin.Lab.2016.161113

  3. Centers for Disease Control and Prevention. National Health and Nutrition Examination Survey.

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