[Genomic Characterization of SARS-CoV-2 Isolates Obtained from Antalya, Türkiye].

Abstract

As the number of coronavirus diseases-2019 (COVID-19) cases have decreased and measures have started to be implemented at an individual level rather than in the form of social restrictions, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) still maintains its importance and has already taken its place in the spectrum of agents investigated in multiplex molecular test panels for respiratory tract infections in routine diagnostic use. In this study, we aimed to present mutation analysis and clade distribution of whole genome sequences from randomly selected samples that tested positive with SARS-CoV-2 specific real-time reverse transcription polymerase chain reaction (rRT-PCR) test at different periods of the pandemic in our laboratory with a commercial easy-to-use kit designed for next-generation sequencing systems. A total of 84 nasopharyngeal/oropharyngeal swab samples of COVID-19 suspected patients which were sent for routine diagnosis to the medical microbiology laboratory and detected as SARSCoV-2 RNA positive with rRT-PCR were randomly selected from different periods for sequence analysis. Library preparation for sequencing was performed with the commerical EasySeq SARS-CoV-2 RC PCR kit (Nimagen, the Netherlands). The data generated from the Illumina MiSeq system (Illumina Inc, San Diego, CA, USA) were analysed using CLC Genomics Workbench (CLC, Qiagen, Hilden, Germany). Nextstrain clades detected in order of frequency were 21J (Delta) (25%, n= 21), 21L (Omicron) (23.8%, n= 20), 20B (19%, n= 16), 20A (15.5%, n= 13), 21K (Omicron) (11.9%, n= 10), 19A (3.6%, n= 3), and 22B (Omicron) (1.2%, n= 1). Excluding one patient sample which was identified as 22B (Omicron), a total of 2829 common distinct mutations (2076 missense, 551 synonymous, 192 deletions and 10 insertions) were detected. 100 mutations were observed in the non-coding 5' untranslated region (UTR). The majority of the mutations were located in the Spike gene region (1120 mutations), followed by the ORF1a (624 mutations), nucleocapside (315 mutations) and ORF1b (263 mutations) gene regions. Sampling times of the patients were March 2020 (n= 1), April 2020 (n= 11), May 2020 (n= 1), June 2020 (n= 2), July 2020 (n= 3), August 2020 (n= 1), September 2020 (n= 5), November 2020 (n= 2), December 2020 (n= 6), December 2021 (n= 19), January 2022 (n= 11), March 2022 (n= 16), April 2022 (n= 3), and June 2022 (n= 3). As a result, in this study, SARS-CoV-2 variants and mutations in the Mediterranean Region of Türkiye, Antalya province were analyzed in detail. To the best of our knowledge, no SARS-CoV-2 genome analysis study from the pandemic period has been reported in our province. When the sequences from our study were uploaded to the GISAID Instant Audacity system and the related genomes obtained from different countries in the EpiCoV database metadata were examined, the top two countries in terms of similarity and which could be associated with the main entry route of the virus into Türkiye were Germany and the United Kingdom. In today's world, where it is discussed what can be done to be prepared for possible new pandemics based on the COVID-19 pandemic, the importance of being proactive in molecular surveillance studies is indisputable. Developing countries should be supported and encouraged to research new variants and share data in addition to known variants in pandemic control. At this point, we believe that past pandemic data reported from different geographical regions will also be valuable in terms of predicting the circulation network and taking precautions in a possible new pandemic.