Dataset Information

Tracking SARS-CoV-2 variants by entire S-gene analysis using long-range RT-PCR and Sanger sequencing.

ABSTRACT:

Introduction

Genomic surveillance of the SARS-CoV-2 virus is important to assess transmissibility, disease severity, and vaccine effectiveness. The SARS-CoV-2 genome consists of approximately 30 kb single-stranded RNA that is too large to analyze the whole genome by Sanger sequencing. Thus, in this study, we performed Sanger sequencing following long-range RT-PCR of the entire SARS-CoV-2 S-gene and analyzed the mutational dynamics.

Methods

The 4 kb region, including the S-gene, was amplified by two-step long-range RT-PCR. Then, the entire S-gene sequence was determined by Sanger sequencing. The amino acid mutations were identified as compared with the reference SARS-CoV-2 genome.

Results

The S:D614G mutation was found in all samples. The R.1 variants were detected after January 2021. Alpha variants started to emerge in April 2021. Delta variants replaced Alpha in July 2021. Then, Omicron variants were detected after December 2021. These mutational dynamics in samples collected in the Chiba University Hospital were similar to those in Japan.

Conclusion

The emergence of variants of concern (VOC) has been reported by the entire S-gene analysis. As the VOCs have unique mutational patterns of the S-gene region, analysis of the entire S-gene will be useful for molecular surveillance of the SARS-CoV-2 in clinical laboratories.

SUBMITTER: Matsubara M

PROVIDER: S-EPMC8923710 | biostudies-literature | 2022 May

REPOSITORIES: biostudies-literature

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Publications

Tracking SARS-CoV-2 variants by entire S-gene analysis using long-range RT-PCR and Sanger sequencing.

Matsubara Mirai M Imaizumi Yuri Y Fujikawa Tatsuki T Ishige Takayuki T Nishimura Motoi M Miyabe Akiko A Murata Shota S Kawasaki Kenji K Taniguchi Toshibumi T Igari Hidetoshi H Matsushita Kazuyuki K

Clinica chimica acta; international journal of clinical chemistry 20220316

<h4>Introduction</h4>Genomic surveillance of the SARS-CoV-2 virus is important to assess transmissibility, disease severity, and vaccine effectiveness. The SARS-CoV-2 genome consists of approximately 30 kb single-stranded RNA that is too large to analyze the whole genome by Sanger sequencing. Thus, in this study, we performed Sanger sequencing following long-range RT-PCR of the entire SARS-CoV-2 S-gene and analyzed the mutational dynamics.<h4>Methods</h4>The 4 kb region, including the S-gene, wa ...[more]

PMID: 35304093

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Project description:COVID-19 resulted in extensive morbidity and mortality worldwide. SARS-CoV-2 evolved rapidly, with increasing transmission due to Variants of Concern (VOC). Identifying VOC became important but genome submissions from low-middle income countries (LMIC) remained low leading to gaps in genomic epidemiology. We demonstrate the use of a specific mutation RT-PCR based approach to identify VOC in SARS-CoV-2 positive samples through the pandemic in Pakistan. We selected 2150 SARS-CoV-2 PCR positive respiratory specimens tested between April 2021 and February 2022, at the Aga Khan University Hospital Clinical Laboratories, Karachi, Pakistan. Commercially available RT-PCR assays were used as required for mutations in Spike protein (N501Y, A570D, E484K, K417N, L452R, P681R and deletion69_70) to identify Alpha, Beta, Gamma, Delta, and Omicron variants respectively. Three pandemic waves associated with Alpha, Delta and Omicron occurred during the study period. Of the samples screened, VOC were identified in 81.7% of cases comprising mainly; Delta (37.2%), Alpha (29.8%) and Omicron (17.1%) variants. During 2021, Alpha variants were predominant in April and May; Beta and Gamma variants emerged in May and peaked in June; the Delta variant peaked in July and remained predominant until November. Omicron (BA.1) emerged in December 2021 and remained predominant until February 2022. The CT values of Alpha, Beta, Gamma and Delta were all significantly higher than that of Omicron variants (p<0.0001). We observed VOC through the pandemic waves using spike mutation specific RT-PCR assays. We show the spike mutation specific RT-PCR assay is a rapid, low-cost and adaptable for the identification of VOC as an adjunct approach to NGS to effectively inform the public health response. Further, by associating the VOC with CT values of its diagnostic PCR we gain information regarding the viral load of samples and therefore the level of transmission and disease severity in the population.

Project description:This study aimed to develop the feasible and effective universal screening strategy of the notable SARS-CoV-2 variants by Sanger Sequencing Strategy and then practically applied it for mass screening in Hiroshima, Japan. A total of 734 samples from COVID-19 confirmed cases in Hiroshima were screened for the notable SARS-CoV-2 variants (B.1.1.7, B.1.351, P.1, B.1.617.2, B.1.617.1, C.37, B.1.1.529, etc.). The targeted spike region is amplified by nested RT-PCR using in-house designed primer set hCoV-Spike-A and standard amplification protocol. Additionally, randomly selected 96 samples were also amplified using primer sets hCoV-Spike-B and hCoV-Spike-C. The negative amplified samples were repeated for second attempt of amplification by volume-up protocol. Thereafter, the amplified products were assigned for Sanger sequencing using corresponding primers. The positive amplification rate of primer set hCoV-Spike-A, hCoV-Spike-B and hCoV-Spike-C were 87.3%, 83.3% and 93.8% respectively for standard protocol and increased to 99.6%, 95.8% and 96.9% after second attempt by volume-up protocol. The readiness of genome sequences was 96.9%, 100% and 100% respectively. Among 48 mutant isolates, 26 were B.1.1.7 (Alpha), 7 were E484K single mutation and the rest were other types of mutation. Moreover, 5 cluster cases with single mutation at N501S were firstly reported in Hiroshima. This study indicates the reliability and effectiveness of Sanger sequencing to screen large number of samples for the notable SARS-CoV-2 variants. Compared to the Next Generation Sequencing (NGS), our method introduces the feasible, universally applicable, and practically useful tool for identification of the emerging variants with less expensive and time consuming especially in those countries where the NGS is not practically available. Our method allows not only to identify the pre-existing variants but also to examine other rare type of mutation or newly emerged variants and is crucial for prevention and control of pandemic.

Project description:BackgroundThe evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) persists, giving rise to new variants characterized by mutations in the spike protein. However, public data regarding the virus's evolutionary trend is not widely available after the downgrade of coronavirus disease 2019(COVID-19). Therefore, this study aimed to investigate the applicability of an in-house Sanger-based method for identifying SARS-CoV-2 variants, particularly focusing on newly emerged Omicron variants, and updating the epidemiology of COVID-19 during the 8th wave in Hiroshima Prefecture.ResultsA total of 639 saliva samples of individuals who had tested positive for COVID-19, received from Hiroshima City Medical Association Clinical Laboratory Center between February 01, 2023, and March 12, 2024, were included in the study. SARS-CoV-2 variants were identified in 69.3% (443/639) with the mean viral titer 2 × 106 copies/mL, and high viral titer in Omicron variant XBC.1.6* (5 × 108 copies/mL) using RT-qPCR. By partial Spike gene-based sequencing using the Sanger Sequencing strategy, Omicron sub-lineages XXB.1, BA.5, and EG.1 were identified during different periods. A comprehensive phylogenetic analysis of 7383 SARS-CoV-2 strains retrieved from GISAID, collected in Hiroshima from the onset of the COVID-19 pandemic in early 2020 until July 2024, revealed the dynamic evolution of SARS-CoV-2 variants over time. The study found a similar pattern of variant distribution between the full genomes from GISAID, and the partial genomes obtained from our screening strategy during the same period.ConclusionsOur study revealed that all SARS-CoV-2 viruses circulated in Hiroshima were Omicron variants and their sub-lineages during the 8th wave outbreak in Hiroshima. Persistent molecular surveillance of SARS-CoV-2 is needed for the decision-making and strategic planning of the public promptly. Our study added evidence for the usefulness of SARS-CoV-2 spike gene partial sequencing-based SARS-CoV-2 variant identification strategy for mass screening and molecular surveillance even though the evolution of newly emerged various SARS-CoV-2 Omicron variants.

Dataset Information

Tracking SARS-CoV-2 variants by entire S-gene analysis using long-range RT-PCR and Sanger sequencing.

Introduction

Methods

Results

Conclusion

Publications

Tracking SARS-CoV-2 variants by entire S-gene analysis using long-range RT-PCR and Sanger sequencing.

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