ELISA, RIBA, and PCR

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Most ELISA tests in current use are very sensitive at picking up antibodies to the hepatitis C virus, but they also have a high rate of false positivity (cases where the test appears positive but the patient is NOT really infected). To be certain that a positive test is truly positive, most testing sites do further testing (called RIBA or Recombinant ImmunoBlot Assay) on all positive sera. A test is reported as positive only if it is confirmed by the RIBA assay. In RIBA testing, recombinant HCV antigens are applied separately onto special paper strips and used to detect the presence and specificity of antibody present in the test serum. Typically, a RIBA test is called positive, confirming HCV infection, if two or more HCV antigens are detected. Third generation ELISA tests are becoming available which are highly specific (99%) for HCV; they are not yet FDA Licensed, Despite the high sensitivity of second generation ELISA tests, antibody production by an infected individual may take up to 3 to 4 months (rarely up to 6 months) to develop. Hence, there remains a "window period" during which the individual is infected but without detectable antibody. Immunosuppressed patients (renal transplant, those on steroids, HIV patients) may also have active HCV infection without detectable antibody.

The original test used to screen you (ELISA) detected antibody to HCV. This antibody is a marker of HCV infection at some time in the past which caused you to produce the antibody in the first place to fight off the original episode of infection.

The test result is normally confirmed by carring out another form of test for antibody called RIBA. The original test simply says you have antibody. The RIBA is capable of showing that you have different types of antibody directed against different proteins from the virus and thereby more specifically confirms the original result.

However, antibody only tells about YOUR body's immune response to the virus and tells nothing about the response of the virus to you.

Did it survive from the original infection or was it eliminated? If if survived and is still in you liver is it active? Is so how active?

These and other questions can be resolved by looking for the virus itself. PCR is a test that looks for viral genetic material in your circulating peripheral blood supply. If it is found ( a positive PCR result) then the virus is still active and producing new viral material. IF positive the amount can be qnantitated to see how much viral genetic material is present, from this the level of activity of the virus can be deduced (the more viral genetic material, the stronger the PCR result, the more active the virus).

Only the lab that carried out the PCR can tell you accurately what your value means. This is because PCR results carried out at different sites can vary due to the way that the individual lab carried out the test.

NOTE: Even if the virus is not circulating in your blood and measurable/detectable by PCR, it often is still lurking in the cells of your body and may return to the blood and the liver.


The links below will take you to more research information

Liver Function Tests A comprehensive article is located http://worldmall.com/erf/lectures/lvr-test.txt

How To Understand Your SMAC Blood Test Report

Common diagnostic tests used in Hepatitis

Clinical Approach to the Patient with Abnormal Liver Test Results

Drugs That May Cause Liver Dysfunction or Damage

Liver & Drug Interaction

Amoxicillin-Clavulanic Acid: Higher Risk Of Hepatotoxicity Than With Amoxicillin Alone


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