Virus diagnostic test may be delayed

Virus diagnostic test may be delayed

The technology needs more confirmatory testing and changes in configuration, officials say

15/05/2020, JACOB KOSHY,NEW DELHI

Fast, but complicated: The new test uses a method called loop-mediated isothermal amplification (LAMP). REUTERSREUTERS

A promising technology developed by a laboratory funded by the Department of Science and Technology to accelerate COVID-19 testing in India may be delayed for several more weeks.

The Chitra GeneLAMP-N, developed by the Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Thiruvananthapuram, needs more confirmatory testing and changes in its configuration, officials said.

The technology uses a method called loop-mediated isothermal amplification (LAMP). The objective, like that of the gold-standard RT-PCR tests, is the same: to detect the presence of viral RNA. Both achieve this via a series of chemical transformations. The LAMP method is said to be faster but is a relatively newer technology, more complicated in its design and has not been tested extensively for COVID-19 detection.

N gene test

Most RT-PCR kits focus on two different genes, the E (envelope) gene and the RdRP (RNA dependent RNA polymerase) gene. The World Health Organization recommends a E and RdRP test, while the U.S.’s Centers for Disease Control and Prevention (CDC) requires an N gene test. The N gene test is a confirmatory test and widely employed in Germany and China, among other countries. However, the design of it is complicated and can be expensive. The CDC protocol says three regions of the N gene must be analysed but the Chitra-model tests two to confirm the identity of the virus.

Though the Chitra test passed an initial assessment by the National Institute of Virology in Alappuzha, a subsequent assessment showed that it was not performing as accurately as desired. “We are testing two N gene regions, so we need to recalibrate the machine to test both of them independently as a common cut-off wasn’t working well,” Asha Kishore, Director, SCTIMST, told The Hindu. “This is expected as all technology being used today [for COVID-19 diagnosis], such as RT-PCR or TruNat, have undergone multiple evaluations. This is a confirmatory test and needs to be absolutely solid. We need time until May end.”

The Chitra test could potentially speed up the testing of a batch of suspected COVID-19 samples by 15 times and cut costs by two-thirds. The technology is licensed to Agappe Diagnostics Ltd., an Ernakulam-based company.

Faster, cheaper

Union Health Minister Harsh Vardhan tweeted: “Sree Chitra Tirunal Institute for Medical Sciences & Tech, Trivandrum, an Institute of National Importance, of the @IndiaDST, has developed a diagnostic test kit that can confirm #COVID19 in 2 hours at a low cost.”

The steady rise in confirmed cases in India is due to an acceleration in testing. The Indian Council of Medical Research reported having tested 1.94 million samples as of Thursday with Dr. Vardhan claiming that India was now testing about 100,000 samples a day.