Rapid direct nucleic acid amplification test without RNA extraction for SARS-CoV-2 using a portable PCR thermocycler

Soon Keong Wee; Suppiah Paramalingam Sivalingam; Eric Peng Huat Yap

The first SARS-CoV-2 genome was published and deposited in NCBI database as Wuhan-Hu-1, GenBank accession number MN908947 on 14 January 2020 (8) . This allowed several laboratories around the world, including our laboratory, to develop nucleic acid amplification tests (NAAT) to detect SARS-CoV-2 genetic materials (9) . Currently, there are many quantitative RT-PCR (RT-qPCR) based NAAT being developed for SARS-CoV-2 (10). These target various viral genes including the nucleocapsid (N), polyprotein (ORF1ab), spike (S) and envelope (E) gene region of the positively stranded 29.9 kb RNA virus. These tests are widely used to screen suspected Covid-19 patients, returning travelers from outbreak areas, close contacts of cases, and healthy individuals who may be asymptomatic carriers of the virus (5, 11) . Typically, respiratory samples such as sputum or nasal, throat, nasopharyngeal swabs collected consecutively over two days are tested to confirm a diagnosis or to confirm recovery. (5) . Diagnostic testing is recognized as a rate-limiting step, and there is a global need to ramp up laboratory capacity, in both well-developed and low-income countries (4, 12) . This is worsened by the possibility that asymptomatic individuals in the community could transmit infection, hence increasing the need to screen healthy individuals or those with mild symptoms (13) (14) (15) .