Optimizing SARS-CoV-2 Molecular Diagnostic Using N Gene Target

Background: Molecular diagnosis of SARS-CoV-2 is a huge challenge to many countries around the world. The cost of tests to check infected people is inaccessible since specialized teams and equipment are not disposable in remote locations. Herein, we compared the fitness of two primers sets to the SARS-CoV-2 N gene in the molecular diagnosis of COVID-19. Methods: The 1029 patient samples were tested to presense/abscence molecular test using in house US CDC protocol. We compared the fitness of two primers sets to two different regions of N gene targets. Findings: Both targets, N1 and N2 displayed similar fitness during testing with no differences between Ct or measurable viral genome copies.  In addition, we verified security ranges Cts related to positive diagnostic with Ct above 35 value failuring in 66,6% after retesting of samples. Interpretation: Our data suggest that it is secure to use just one primer set to the N gene to identify SARS-CoV-2 in samples and the labs should be careful to set positive samples in high Ct values using high cutoffs. Funding: Associacao Baiana de Produtores de Algodao (ABAPA); Associacao Baiana de Agricultores Irrigantes da Bahia (AIBA); Fundacao de Amparo a Pesquisa do Estado da Bahia (FAPESB) (Grant Number: #1381/2020); FINEP (Grant Number: # 0418000600); CNPq; CAPES, MEC, MCTIC. Declaration of Interests: None to declare. Ethics Approval Statement: The Research Ethics Committee of UFOB approved this study in 2020 (license number: 30629520.6.0000.0008). All clinical investigations were conducted according to the Declaration of Helsinki.