Nirmalya Dey, PhD
An ardent reader (especially ‘bong’) not liking the thin and tall Calabash-holder of 221B Baker Street or the 6’2’’ Charminar-smoker of 21 Rajani Sen Road, is perhaps as rare as an empty bus during office rush. The 134-year-old British ‘consulting detective’ and his half-aged ‘(self-declared) mentee’, the Bengali ‘private investigator’, still stand larger than fictional creation to thrill us with their finest faculty of observation, deduction, and intellect in detection of crime. The pandemic of COVID-19 has wreck-havocked the world in last 20 months or so in every aspect. Appropriate detection of the pathogen is of prime-most importance in this circumstance to build up a countermeasure; especially with the knowledge of the fact that the virus is continually evolving to yield various strains. The canonical RT-PCR method has been deployed as the ‘gold standard’ for confirmatory detection above other diagnostic measures (eg. antibody and protein-based) since the beginning. However, a specific and sensitive faster method involving simpler (or none, at the best) instrumentation was of immense urge in observance of mammoth sample load piling everyday worldwide. Thus, reincarnated SHERLOCK and FELUDA: in avatar of ‘diagno-sleuths’.
SHERLOCK:-
The story essentially began in a 2011 scientific meeting between Drs. Emmanuelle Charpentier (Max Planck Unit for the Science of Pathogens) and Jennifer Doudna (University of California, Berkeley). Their combined brainstorming had led to the discovery of CRISPR/Cas9 genome editing technology, an otherwise ancient bacterial adaptive immune system exploited to function as genetic scissor. The discovery eventually culminated in the form of Nobel prize in Chemistry awarded to them in 2020. Six months later to the publication of the first evidence of bacterial genome editing by this scientist duo in 2012, Dr. Feng Zhang (Broad Institute) and others in Boston demonstrated CRISPR functionality in mammalian cells. Later, Zhang laboratory established a CRISPR-based diagnostic platform combining nucleic acid pre-amplification with CRISPR-Cas enzymatic recognition for rapid detection of specific ‘target’ nucleic acid, crucial for clinical diagnostic application. This platform for portable, multiplexed, high-sensitive detection of DNA/RNA from clinically relevant samples was termed as ‘SHERLOCK’ (Specific High-sensitivity Enzymatic Reporter unLOCKing). Sherlock CRISPR SARS CoV-2 kit, developed by Sherlock Biosciences (Massachusetts, USA) and approved by the US FDA on Emergency Use Authorization (EUA) basis, has been considered the first application of SHERLOCK technology.
FELUDA:-
Albeit SHERLOCK made diagnosis simplified, its success mandates use of a reporter instrument (a fluorescence plate reader). FELUDA made its entry, almost at the similar time of SHERLOCK, to make it simpler, capable to be used in limited resource condition and more affordable with respect to point-of-care application. The lateral flow-based viral detection system on paper-strips was developed by Drs. Debojyoti Chakraborty and Souvik Maiti of Council of Scientific and Industrial Research’s constituent lab, the Institute of Genomics and Integrative Biology (CSIR- IGIB), New Delhi, India and commercialized by the TATA group. The assay system was coined the name ‘FELUDA’ (FnCas9 Editor Limited Uniform Detection Assay). TATA group had received the approval for commercial launch for this system in May 2020 by Drug Controller General of India.
CHOCCH: Eyeing the future beyond: –
We, at I3TK, are aiming to perform innovations and inventions in the field of biomedical sciences to be subsequently translated in improvement public health and to conduct advanced diagnostic technology implied at molecular levels for betterment of societal living quality and community serving. We are implementing various research and development programs and Diabetes, as a potent public health threat, is a significant name in the list. Recently, we are carrying out research work on development of detection tool, evaluation of therapeutic efficacy and amelioration of microvascular diabetic complications, especially Diabetic Retinopathy. The current global burden of diabetes is more than 463 million and diabetic ocular complications (non-proliferative, proliferative forms of Diabetic Retinopathy, Diabetic Macular Edema etc.) belong to the high-risk category of diabetic fallouts. A quarter to 1/3rd of diabetic population tends to develop sight-threatening consequences and about 80% of legal blindness is attributed to Diabetic Retinopathy. A proper diagnosis and precise detection of disease situation plays a pivotal role in treatment, especially considering the insidious nature of the diabetes. Circulatory nucleic acids have been observed to be differentially regulated in individuals with or without Diabetic Retinopathy and in instances, stage-specific disease condition. These can serve as novel and reliable biomarkers for ailment. Moreover, differential expression of signature nucleic acid biomarkers may reflect the patient’s propensity to respond to the therapeutic regime. We are working on developing a novel non-invasive portable point-of-care biomarker-driven enzymatic reporter readout perception platform at our institute to distinguishingly detect stage-specific diabetic ocular complications and evaluation of treatment efficacy. We call it ‘CHOCCH’ (Cas-mediated High specific detection of OCular Complications of Hyperglycemia).
Kellner et. al. Nature Protocols (2019) 14: 2986–3012.
Uyhaji and Benette J Clin Invest. (2021) 131(1): e145214.
IDF Diabetes Atlas 9th Edition (2019).
https://www.fda.gov/media/137747/download
https://sherlock.bio/sherlock-biosciences-announces-discovery-of-novel-crispr-cas-enzymes-enabling-simple-multiplex-diagnostic-solutions/
https://www.milenia-biotec.com/en/feluda-test-rapid-covid-detection/
https://www.hindustantimes.com/health/feluda-the-cheaper-crispr-based-covid-test-launched-by-tata-group/story-NURoWRmh7KE2OVKbTeFQsO.html
