Validação da PCR convencional como alternativa de diagnóstico de SARS-COV-2 em amostras humanas

Abstract

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has spread around the world and has become a global health problem. As a result, the demand for diagnostic tests has increased dramatically, as has the cost of equipment and supplies. Countries with poor laboratory infrastructure face difficulties in expanding their testing capacity through Real-Time Reverse Transcription-Polymerase Chain Reaction (RT-qPCR); therefore, the development of sensitive and specific alternative methods is essential to expand the testing network, reducing underreporting. This study aimed to develop, standardize, optimize and validate the conventional Reverse Transcription-Polymerase Chain Reaction (RT-PCR) targeted at the N gene of SARS-CoV-2 in naso-oropharyngeal swab samples compared to RT-qPCR. Using bioinformatics tools, primers for the N gene were determined and optimized. Reaction conditions were optimized using a commercial positive control and the detection limit was determined at 100 viral copies. In the validation of conventional RT-PCR, a representative sample of 346 samples from patients with suspected infection was determined, whose diagnosis was made in parallel with RT- qPCR, without access to Cycle Threshold (Ct) values. There was a sensitivity of 92.1% and specificity of 100%, an accuracy of 95.6% and a correlation coefficient of 0.913. Under current Brazilian conditions, this method generated approximately 60.0% savings compared to RT-qPCR costs. Conventional RT-PCR, validated by the present work, showed sufficient results for the detection of SARS-