Volume 96 Issue 5 | p. 11 | Concentrates
Issue Date: January 29, 2018

Detecting Ebola immunity with a paper test

Antibody-detecting test strips that can be read with smartphones hold promise for disease monitoring and vaccine development
Department: Science & Technology
Keywords: Diagnostics, Ebola, antibody detection, point-of-care test, paper test, smartphone, antigens
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A paper-based test detects antibodies against Ebola virus. Droplets of blood serum (left) and a solution of antibody-labeled gold nanoparticles (blue and yellow) placed on one end of the strip wick through printed test lines of Ebola antigens (yellow, red, and green squares). If Ebola antibodies are present in the serum, the test lines turn color. A control line of antibodies (purple) turns color to indicate that the test is working.
Credit: ACS Nano
Illustration of a paper strip for detecting Ebola antibodies showing a serum sample being added to one end and regions of the strip containing antibody-gold nanoparticle conjugates, three lines of Ebola virus antigens, and one line of control antibodies. Sample flow goes from left to right and takes 15 minutes.
 
A paper-based test detects antibodies against Ebola virus. Droplets of blood serum (left) and a solution of antibody-labeled gold nanoparticles (blue and yellow) placed on one end of the strip wick through printed test lines of Ebola antigens (yellow, red, and green squares). If Ebola antibodies are present in the serum, the test lines turn color. A control line of antibodies (purple) turns color to indicate that the test is working.
Credit: ACS Nano

To help combat deadly outbreaks of Ebola, health care workers need a simple, portable test to determine immune response to the disease. Now, researchers have developed a color-changing, paper-based strip that detects antibodies against the virus in blood serum (ACS Nano 2018, DOI: 10.1021/acsnano.7b07021). Molly M. Stevens of Imperial College London and colleagues printed lines containing three antigens produced by different subtypes of the Ebola virus on one end of a commercially available paper test strip. To use the paper device, the team delivers a drop of blood serum to the other end of the strip and follows it with a solution of antibodies that label the target Ebola antibodies with gold nanoparticles. As the fluids wick past the test lines, Ebola antibodies in the serum bind to the nanoparticles and then to the antigens, causing the test lines to turn reddish purple within 15 minutes. A smartphone app measures the intensity of the line colors to give a positive or negative result. Compared with results from the gold standard lab-based assay, the test was 100% accurate at detecting individuals who had survived Ebola and gave one false positive with an uninfected sample.

 
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ISSN 0009-2347
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