What Is the Western Blot Test?

Deoxyribonucleic acid (DNA) protein strand
••• DNA image by Allyson Ricketts from Fotolia.com

The Western blot test, also called immunoblotting, is a test for a specific protein within a protein mixture. The Western blot test is performed after gel-electrophoresis or an enzyme-linked immunosorbent assay (ELISA) test, and it uses antibodies to identify specific proteins.


Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) is a common test used to separate proteins for use in the Western blot. The proteins are separated by weight and electrical properties as they move through a gel matrix.


The ELISA test uses enzymes or antibodies attached to a solid surface to create the test surface. A sample is then added to the test surface. Antibodies or enzymes reacting or attaching to proteins indicates a positive result.

Western Blot

The Western blot test is performed after the gel-electrophoresis. The separated proteins are transferred (or blotted) onto nitrocellulose or nylon membranes and identified by specific antibodies that are tagged by a secondary protein.

Positive Test Confirmation

The Western blot test is used to confirm positive results from either gel-electrophoresis or ELISA tests. The Western blot test can identify proteins more specifically and can rule out false positives.


The Western blot test is generally used to confirm positive test results for human immunodeficiency virus (HIV) and Lyme disease.

Related Articles

How to Read a Western Blot
The Purpose of Electrophoresis
List of the Applications of Electrophoresis
How Does Alcohol Kill Bacteria?
Electrophoresis Process
Test Your Knowledge on Middle School Science
What are Specific Biotechnology Applications for DNA...
The Disadvantages of Western Blotting
Difference Between Attached & Detached Ribosomes
How to Test for Hydrochloric Acid
Recombinant DNA Technology for Vaccine Development
How to Identify Enterobacter Aerogenes API 20E
Dielectric Breakdown Vs. Insulation Resistance Test
What Is the Function of Tracking Dye in Gel Electrophoresis?
Characteristics of Salmonella Bacteria
Advantages and Disadvantages of Western Blot
Importance of Free Ribosomes
Industrial Uses of Pepsin
What Is a Mordant in Microbiology?
The Causes of High Single Stranded DNA Antibodies