The Indian Council of Medical Research (ICMR) has recently approved a new cost-effective Covid-19 diagnostic method called COVIRAP. This innovative tool was developed by the Indian Institute of Technology (IIT), Kharagpur, and offers a range of key features that enhance the efficiency and effectiveness of Covid-19 diagnosis.
The Operational Mechanism of COVIRAP
COVIRAP works through an automated pre-programmable temperature control unit, a genomic analysis-specific detection unit, and a customized smartphone app for displaying results. Its main mechanism of operation is an isothermal nucleic acid amplification process, which essentially eliminates the need for a thermocycler in the virus detection procedure. Isothermal Amplification Techniques were developed as alternatives to Polymerase Chain Reaction (PCR).
Thermocyclers, which are essential tools in the context of PCR, are used to amplify DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) samples. Instead of using these instruments, COVIRAP utilises specially treated paper strips; once the sample is processed in the machine after being combined with solutions developed by the IIT team, these paper strips are dipped into it. The appearance of coloured lines signifies the presence of the virus.
The Multiple Advantages of the COVIRAP Process
The benefits of COVIRAP are numerous, starting from its cost-effectiveness. The machine costs less than Rs. 5,000, and each test kit is approximately Rs. 500, making it a cheaper alternative for Covid-19 diagnosis. The speed of testing is another advantage; COVIRAP completes the test within an hour, compared to the 3-4 hours required by the Reverse Transcription Polymerase Chain Reaction (RT-PCR) test.
Additionally, the portability and simplicity of the COVIRAP test unit make it easily manageable by unskilled operators outside a lab environment. The unit is superior to the FELUDA test that employs the CRISPR-cas9 gene editing technology, thereby necessitating a lab testing environment.
Moreover, the same COVIRAP unit can be reused for a large number of tests by simply replacing the paper cartridge after each test. This diagnostic tool is capable of detecting extremely low levels of viral loads, allowing for early detection of infection and facilitating prompt isolation of the patient to prevent uncontrolled spread of infection in the community via asymptomatic patients.
Accuracy of COVIRAP
In terms of accuracy, COVIRAP detected 108 out of 115 positive samples and 83 out of 85 negative samples as identified by an RT-PCR machine. This suggests a 94% sensitivity and 98% specificity compared to RT-PCR.
Additional Uses of COVIRAP
Beyond Covid-19 diagnosis, the COVIRAP testing machine can be employed in diagnosing other diseases, including influenza, malaria, dengue, Japanese encephalitis, and TB. All these conditions fall under the category of isothermal nucleic acid-based tests.
Understanding RT-PCR Test
The PCR technique, which forms the basis for the RT-PCR test, was invented by Kary Mullis, an American biochemist who received the Nobel Prize for Chemistry in 1993 for this groundbreaking invention.
In this procedure, copies of a DNA segment are created using an enzyme known as Polymerase. During this ‘chain reaction’, the DNA fragments are exponentially copied: one is transformed into two, the two into four, and so on. To reveal the presence of the virus, a fluorescent DNA binding dye called the “probe” is added to the DNA, and its presence is indicated on a fluorometer.
Since the coronavirus consists of RNA (ribonucleic acid), it is necessary to convert the RNA into DNA to detect the virus. This conversion is achieved using a technique called reverse transcription, with an enzyme known as ‘reverse transcriptase’ carrying out the conversion. Copies of the DNA are then made and amplified for diagnosis.
