Rapid Base-Specific Calling of SARS-CoV-2 Variants of Concern Using Combined RT-PCR Melting Curve Screening and SIRPH Technology.

BACKGROUND: The emergence of novel variants of concern of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) demands fast and reliable detection of such variants in local populations. METHODS: Here we present a cost-efficient and fast workflow combining a prescreening of SARS-CoV-2-positive samples using reverse transcription polymerase chain reaction melting curve analysis with multiplexed IP-RP-HPLC-based single nucleotide primer extensions. RESULTS: The entire workflow from positive SARS-CoV-2 testing to base-specific identification of variants requires about 24 hours. CONCLUSIONS: We applied the sensitive method to monitor local variant of concern outbreaks in SARS-CoV-2-positive samples collected in a confined region of Germany.

Detailed methylation map of LINE-1 5'-promoter region reveals hypomethylated CpG hotspots associated with tumor tissue specificity.

BACKGROUND: Long interspersed nuclear elements (LINE-1) sequences constitute a substantial portion of the human genome, and their methylation often correlating with global genomic methylation. Previous studies have highlighted the feasibility of using LINE-1 methylation to discriminate tumors from healthy tissues. However, most studies are based on only a few specific LINE-1 CpG sites. METHODS: Herein, we have performed a systematic fine-scale analysis of methylation at 14 CpGs located in the 5'-region of consensus LINE-1, in bladder, colon, prostate, and gastric tumor tissues using a global degenerate approach. RESULTS: Our results reveal variable methylation levels between different CpGs, as well as some tissue-specific differences. Trends toward hypomethylation were observed in all tumors types to certain degrees, showing statistically significance in bladder and prostate tumors. Our data points toward the presence of unique LINE-1 DNA methylation patterns for each tumor type and tissue, indicating that not the same CpGs will be informative for testing in all tumor types. CONCLUSION: This study provides an accurate guide that will help to design further assays that could avoid artifacts and explain the variability of obtained LINE-1 methylation values between different studies.

DNA methylation at selected CpG sites in peripheral blood leukocytes is predictive of gastric cancer.

BACKGROUND/AIM: Recently, a set of studies addressed the question of the prevalence of aberrant methylation in surrogate tissues, such as peripheral blood leukocytes. Toward this aim, we conducted a case-control pilot study to investigate aberrant methylation in leukocytes of gastric cancer patients. MATERIALS AND METHODS: The SNuPE combined with ion pair reverse phase HPLC (SIRPH method) was used to examine site-specific methylation status at selected CpG sites of the promoter regions of APC, ACIN1, BCL2, CD44, DAPK1, CDKN2A, RARB, TNFRSF10C HS3ST2 and of LINE-1, Alu repeats. RESULTS: We observed that in the patients, tumor suppressor genes were slightly but significantly higher methylated at several CpG sites, while DNA repetitive elements were slightly less methylated compared to controls. This was found to be significantly associated with higher prevalence for gastric cancer. CONCLUSION: These results suggest that larger studies must be carried-out to explore the biological significance and clinical usefulness of leukocyte DNA as non-invasive detection tool for gastric cancer.