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ELISA or PCR? Not all tests are created equal

22 February 2018

Thermo Fisher Scientific

Many people are confused about how to apply diagnostic methods. Although the diagnostics field is rapidly developing, the most used diagnostic techniques are still ELISA and PCR. When to use which, depends on the question. Reviewing the differences between ELISA and PCR can help, writes Nardy Robben, product application specialist at Thermo Fisher Scientific.

This article first appeared in Pig Progress.

ELISA – A look into the past

Nardy Robben, product application specialist at Thermo Fisher Scientific

When an animal is infected, its immune system will build antibodies against the causative pathogen as a reaction to the infection. ELISA, an acronym for Enzyme-linked Immunosorbent Assay, is a diagnostic test designed to detect these pathogen-specific antibodies. While ELISA tests can also be used for antigen detection, it is mostly used for the detection of antibodies. If a specific pathogen’s antibodies are found in the blood, it means the infection occurred sometime in the past. The pathogen itself may, however, no longer be present.

ELISA is used to monitor herd health by screening for changes in antibody status. The big advantage of ELISA tests is the time window for detection of the infection is much longer, making it more probable to detect whether an infection is happening or has happened. It is often used in the field because it’s an easy-to-use detection method for both large and small laboratories. Antibodies in the blood samples are relatively stable, making sampling and transport easy.

ELISA has been available globally for more than 20 years, and a lot of experience has been assembled with this type of test. Because ELISA provides herd level information of past infections, it can test positive for antibodies long after the infection has left the herd, in some cases, the pig’s entire life. To detect new infections, veterinarians often use ELISA antibody levels to track historical changes in the herd. By comparing previous antibody levels with the current status, they can gain insight into whether a new virus or pathogen infection has recently occurred in the herd.


Further Reading

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For more information about swine diagnostics, click here or connect to the Thermo Fisher Scientific Swine Resource Center.


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