Explained: FELUDA paper strip test for coronavirus
Context: Union Health Minister rollout FELUDA paper strip test for coronavirus.
Tests on over 2000 patients during the trials at the CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB) and in private labs, showed that the test had 96% sensitivity and 98% specificity.
What is FELUDA?
- FELUDA is an acronym for FNCAS9 Editor-Limited Uniform Detection Assay.
- It uses CRISPR-Cas technology for the detection of genes specific to SARS-CoV-2 virus.
- In this method, a protein called FnCas9 and a guide RNA(gRNA) which helps in recognising the viral genes is used.
- If the patient sample has the viral gene, this gRNA-FnCas9 complex binds to the gene and using a paper strip this binding can be visualised.
How is the test done?
- The nasopharyngeal swab is collected
- RNA is extracted
- A single step RT-PCR is done
- The FELUDA mix is prepared by incubating the dead FnCas9 protein, guide RNA and the amplified viral DNA
- The dip stick is immersed in the FELUDA mix
- Gold nanoparticle on the strip bind to the FELUDA complex
- A protein called Streptavidin on the test line captures this gold nanoparticle bound-FELUDA complex
- Unbound gold particles are captured on the control line
- Colour develops on the test line and/or control line. One line indicates negative and two lines mean positive.
- The test takes about one to two minutes
Is it better than RT-PCR?
- RT- PCR equipment and reagents are costly and a technical expertise is needed.
- With FELUDA, the need for technical expertise is minimal and no requirement of expensive equipment, making it an easy to perform, point of care test.
- It saves space, time and money.
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