Monitoring the SARS-CoV-2 pandemic: screening algorithm with SNP detection for the rapid identification of established and emerging variants

Mertens, Joachim; Coppens, Jasmine; Loens, Katherine; Le Mercier, Marie; Xavier, Basil Britto; Lammens, Christine; Vandamme, Sarah; Jansens, Hilde; Goossens, Herman; Matheeussen, Veerle

OBJECTIVES: The current study evaluates a testing algorithm for the rapid identification of SARS-CoV-2 variants that includes the use of PCR-based targeted Single Nucleotide Polymorphism (SNP) detection assays preceded by a multiplex PCR sensitive to s-Gene Target Failure (SGTF). METHODS: PCR SNP assays targeting SARS-CoV-2 s-gene mutations ΔH69-V70, L452R, E484K, N501Y, H655Y, and P681R using melting curve analysis were performed on 567 samples in which SARS-CoV-2 viral RNA was detected by a multiplex PCR. Viral whole genome sequencing (WGS) was performed to confirm the presence of SNPs and to identify the Pangolin lineage. Additionally, 1133 SARS-CoV-2 positive samples with SGTF were further assessed by WGS to determine the presence of ΔH69-V70. RESULTS: The N501Y-specific assay (N=567) had an overall percent agreement (OPA) of 98.5%. The ΔH69-V70- (N=178) and E484K-specific (N=401) assays had an OPA of 96.6 and 99.7% respectively. Assessment of H655Y (N=139) yielded a 100.0% concordance when applied in the proposed algorithm. The L452R- (N=67) and P681R-specific (N=62) assays had an OPA of 98.2 and 98.1% respectively. The proposed algorithm identified six variants of concern/interest (VOC/VOI) – Alpha (N=149), Beta (N=65), Gamma (N=86), Delta (N=49), Eta (N=6), Kappa (N=6) – and 205 non-VOC/VOI strains – including the variants under monitoring B.1.214.2 (N=43) and B.1.1.318 (N=18) and Epsilon (N=1). An excellent concordance was observed for the identification of all SARS-CoV-2 lineages evaluated. CONCLUSIONS: We present a flexible testing algorithm for the rapid detection of current and emerging SARS-CoV-2 VOC/VOIs which can be easily adapted based on the local endemicity of specific variants.