What is the TrueNat TB Test?
TrueNat was originally developed to detect Tuberculosis (TB) in one hour. Both TrueNat Xpert MTB and TrueNat Xpert MTB Plus were used to detect TB. It is a portable, chip-based and battery-operated machine developed by a Goa-based company. The World Health Organisation has approved TrueNat for detecting TB as it is cost-effective and a miniature version of the PCR test.
TrueNat test for COVID-19
The Indian Council of Medical Research has recently approved the use of TrueNat devices for conducting covid-19 tests. Moreover, being portable, the devices can be carried to remote places to quickly screen covid 19.
For testing the COVID- 19 virus, the kit was modified by the company. The sample of the throat and the nasal swab is now collected by the trained technicians wearing PPE (personal protective equipment).
The SARS-CoV-2 virus that causes COVID-19 does not have DNA, but has an RNA molecule. The RT (reverse transcription) process in the RT-PCR converts the RNA into the DNA molecule before the gene is captured in the test.
TrueNat is a chip-based, battery-operated RT-PCR kit. Earlier, it could only identify the E-gene in the SARS-CoV-2 virus that causes COVID-19. E-gene helps the virus build a spherical envelope around it. But the current devices are now equipped to detect the RdRp enzyme found in the virus RNA. Therefore, ICMR has ruled that these tests can be treated as a confirmation for the presence of COVID-19 virus.
Revised Guidelines for TrueNat for Covid-19
There are now 3 types of TrueNat assays available, according to the Indian Council of Medical Research (ICMR).
- Assay 1- TrueNat Beta CoV E gene Screening assay.
- Assay2- TrueNat SARS CoV 2 RdRp gene confirmatory assay.
- Assay 3-TrueNat Covid 19 Multiplex assay, which includes a single step that does both screening (E gene) and confirmation (Orf1a). All negative reports are considered true negatives, and all positive reports are considered true positives.
What samples are used for the test?
To conduct the TrueNat test in full form trained technicians collect the sample of the throat and the nasal swab. The Covid 19 causing virus called the SARS-CoV-2 does not have DNA but has an RNA. The RT process in the RT-PCR converts the RNA into DNA before testing the gene.
Duration of the test
For DNA extraction, it takes 25 minutes and for diagnosis 35 minutes. Thus a total of one hour is required for the TB test. For Rifampicin, it takes an additional hour. Covid-19 screening and confirmation is a two-step process. For detecting the COVID – 19 virus, it takes 2 hours.
The machine has the capacity to run up to 45 samples of multiple diseases including COVID-19, HIV and TB in a four-way.
Results of TrueNat
After the E-gene screening assay for COVID – 19 cases, the positive samples are subjected to RdRp gene confirmatory assay. If the results are positive, then the patients are identified as COVID- 19 positive. TrueNat tests are declared as the final confirmatory test for COVID- 19 suspects.
Accuracy of the TrueNat test
TrueNat tests showed 99% specificity against sputum microscopy. The sensitivity to TB was 89% with the TrueNat MTB assay. The results are compared with the Xpert diagnostic test and were found to be more sensitive and specific.
The rate of detection of TB was 30% more in TrueNat than smear microscopy. This test has increased the diagnosis of TB and reduced the incidence and transmission. TrueNat tests have a higher percentage of accuracy and specificity for the Covid-19 virus, similar to Genexpert.
TrueNat test procedure
The screening of Covid 19 is a two-step process; therefore, it takes two hours to complete the procedure. The samples are collected in a viral lysis buffer that requires minimum biosecurity and biosafety.
Step 1: TrueNat Beta CoV E gene screening. In this step, all negative reports are considered as Covid Negative. All the positive samples are sent for confirmation by the second step.
Step 2: TrueNat Beta CoV 2 RdRp gene confirmation. In this step, all the positive results are confirmed as true Covid 19 positives.
How Does the TrueNat Test Work?
The TrueNat test was 99% specific against sputum microscopy and 89% sensitive to Tuberculosis. TrueNat tests are highly accurate and precise in the detection of Covid 19.
TrueNat test is quicker and cheaper than PR-PCR testing. It can be used to screen covid-19 in both containment zones and mobile testing centres. Moreover, sample collection and analysis can be done with minimal training.
TrueNat is a comprehensive test for screening and confirming the COVID-19 virus in India. The ICMR has approved the use of modified TrueNat test kits for the confirmation of COVID- 19.
TrueNat is battery operated, cheaper, and quicker than other RT- PCR tests. They can be used to test the samples in the containment zone and for creating mobile testing centres. With minimal training, both sample collection and analysis can be performed. These were the main reasons for ICMR accreditation to the TrueNat test.
What is the difference between TrueNat and other Covid-19 test kits?
TrueNat is the only device that can be carried to remote districts. TrueNat kit is priced Rs.1300 and this is very less than large RT-PCR kits.
What is present in the TrueNat chip for detecting the COVID- 19 viruses?
The chip is loaded with all the calculations required for detecting the virus in the sample.
How long can we operate the machine on a full charge?
The machine will function for ten hours upon full charge. TrueNat machines can be run 24 hours a day.
How many tests are completed in eight hours?
TrueNat can complete 45 tests for an eight-hour shift.
Name the tests available for confirming Tuberculosis. Which is the most accurate one?
The Mantoux Tuberculin skin test, AFB smear microscopy test, Direct sputum smear microscopy, TB blood test, and TrueNat molecular test for TB are the tests available for confirming TB. The test with higher accuracy is the TrueNat test.
How many diseases are detected with this chip-based RT-PCR?
TrueNat can detect TB, HIV, and Covid-19. By feeding the respective disease profile in the machine, we can process multiple diseases at a time in their TrueNat four-way machine.
Is TrueNat Test Reliable?
Yes, TrueNat for covid has a high percentage of accuracy and specificity.
What is the difference between TrueNat and RT-PCR?
The TrueNat machine is portable and can be carried to remote places. Moreover, Covid TrueNat Test is quicker and cheaper than RT-PCR.
What is Truenat covid test time?
TrueNat covid test time is 2 hours. TrueNat Test for covid-19 result time is 2 hours because there are two steps involved.
How accurate is the Truenat Test for covid 19?
TrueNat Test for covid 19 accuracy and specificity is high, similar to Genexpert.