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Abstract

rRT-PCR assay which firstly used for diagnosis of SARS-CoV-2 was developed at the Charité Institute of Virology in Germany and approved by the WHO on January 13, 2020 [8]. This assay targeted the E gene of the COVID-19. Later on, many assays were developed and validated targeting different genes of COVID-19 such as nucleoprotein (N) gene, open reading frame (ORF) gene, spike (S) gene, etc. Although there were no significant differences in the results across gene targets in many studies, significant differences were found in Ct values in commercial kits targeting all genes except S gene [9]. Pojul et al. [10] found that the N gene requires a longer period of days to become negative compared to the ORF gene, the percentage of the N gene was (12.68%), while the percentage of the ORF gene was (12.09%). The objective of the current study was to compare between different sampling methods for the diagnosis of COVID-19 based on the Ct values of both N and ORF1ab genes. DiscussionIn the current study, 49 COVID-19 positive cases were included for comparison. Three different samples (nasopharyngeal swab, throat swab and saliva) were collected from each case. Moreover, 17 out of the 49 positive cases were selected randomly and monitored after 5 days. The monitoring aimed to compare the availability of the virus based on Ct values and the gene amplification in each sample. The study was conducted during the time period from December, 2020 to April, 2021. This study was approved by Libyan National Committee for Biosafety and Biotechnology.