Introduction of STexS Ⅱ: implementing ‘Com probes’ to enhance specificity of high Tm mutant probes

The initial introduction of utilizing double helix structural oligonucleotides known as SNP typing with excellent specificity (STexS) in a standard PCR greatly improved detecting single nucleotide polymorphisms (SNP) by enhancing amplification rates of primer-matching strands and interrupting mismatched strands by constant instability of kinetics regarding alignment attaching and detaching. The model was overall beneficial in detecting SNP mutations which were consisting large amounts of wildtype strands such as EGFR mutation genotyping for early detection of non-small cell lung cancer. While the STexS PCR is advantageous in detecting SNPs and biomarkers, limitations were yet observed. Despite the ability of detecting variants 10 times more effective than a typical amplification-refractory mutation system (ARMS) PCR, it could only perform optimally in DNA concentrations around 101~105. To further enhance STexS specificity to perform detecting viral-RNA variants such as the infamous SARS-CoV-2, a novel improvement of the regular TaqMan Probe using Com-probes to inhibit high copy wild targets and amplify low copy mutant targets. By introducing the novel STexS Ⅱ, omicron variants of SARS-CoV-2 was able to be successfully detected in high concentrations of normal genes.