Random mutations and recombinations are the main sources for the genetic diversity in SARS-CoV-2, with mutations in the SARS-CoV-2 spike (S) receptor binding motif (RBM) representing a high potential for the emergence of new putative variants under investigation (VUI) or variants of concern (VOC). It is of importance, to measure the different circulating SARS-CoV-2 lineages in order to establish a regional SARS-CoV-2 surveillance program. We established whole genome sequencing (WGS) of circulating SARS-CoV-2 lineages in order to establish a regional SARS-CoV-2 surveillance program.
We established a surveillance program for circulating SARS-CoV-2 lineages by performing whole genome sequencing (WGS) in SARS-CoV-2 isolates. Specimens were collected over a period of 5 months from three different sites. Specimens were collected from both patients suffering from COVID-19 and from outpatients without any clinical signs or symptoms; both in a tertiary university hospital, and two private laboratories within an urban area of eastern part Germany.
Viral WGS from the 364 respiratory specimens with positive SARS-CoV-2 RT-PCR comprised 16 different SARS-CoV-2 lineages. The majority of the obtained sequences (252/364=69%) was assigned to the variant of concern (VOC) Alpha (B.1.1.7). This variant first appeared in February in our samples and quickly became the dominant virus variant. All SNP PCR results could be verified using WGS. Other VOCs found in our cohort were Beta (B.1.351, n=2) and Delta (B.1.617.2, n=1).
Lineage analysis revealed 16 different virus variants among 364 respiratory samples analyzed by WGS. The number of distinct lineages dramatically decreased over time in leaving only few variants, in particular, the VOC Alpha or B.1.1.7. By closer inspection of point mutations, we found several distinct mutations of the viral spike protein that were reported to increase affinity or enable immune escape. Within a study period of only 5 months, SARS-CoV-2 lineage B.1.1.7 became the dominant lineage in our study population. This study emphasizes the benefit of SARS-CoV-2 testing by WGS. The increasing use of WGS to sequence the entire SARS-CoV-2 genome will reveal additional VUIs and VOCs with the potential to evade the immune system and, thus, will be a promising tool for data mining of relevant information for epidemiological studies. SARS-CoV-2 lineage monitoring using WGS is an important surveillance tool for early detection of upcoming new lineages of concern.