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.

Comparison of initial oral microbiomes of young adults with and without cavitated dentin caries lesions using an in situ biofilm model

Dental caries is caused by acids released from bacterial biofilms. However, the in vivo formation of initial biofilms in relation to caries remains largely unexplored. The aim of this study was to compare the oral microbiome during the initial phase of bacterial colonization for individuals with (CC) and without (NC) cavitated dentin caries lesions. Bovine enamel slabs on acrylic splints were worn by the volunteers (CC: 14, NC: 13) for in situ biofilm formation (2 h, 4 h, 8 h, 1 ml saliva as reference). Sequencing of the V1/V2 regions of the 16S rRNA gene was performed (MiSeq). The relative abundances of individual operational taxonomic units (OTUs) were compared between samples from the CC group and the NC group. Random forests models were furthermore trained to separate the groups. While the overall heterogeneity did not differ substantially between CC and NC individuals, several individual OTUs were found to have significantly different relative abundances. For the 8 h samples, most of the significant OTUs showed higher relative abundances in the CC group, while the majority of significant OTUs in the saliva samples were more abundant in the NC group. Furthermore, using OTU signatures enabled a separation between both groups, with area-under-the-curve (AUC) values of ~0.8. In summary, the results suggest that initial oral biofilms provide the potential to differentiate between CC and NC individuals.