In this report, we describe the development and initial validation of novel SARS-COV-2 Omicron-specific reactions that enable the identification of Omicron (BA.1) and BA.2 variants. Mutations that are either shared by both BA.1 and BA.2, or are exclusive for BA.1 or for BA.2 were identified by bioinformatic analysis, and corresponding probe-based quantitative PCR reactions were developed to identify them. We show that multiplex combinations of these reactions provide a single-reaction identification of the sample as BA.1, BA.2, or as non-Omicron SARS-COV-2. All four reactions described herein have a sensitivity of less than ten copies per reaction, and are amendable for multiplexing. The results of this study suggest that the new assays may be useful for testing both clinical and environmental samples to differentiate between these two variants.
In this report, we describe a national-scale monitoring of the SARS-COV-2 (SC-2) variant dynamics in Israel, using multiple-time sampling of twelve wastewater treatment plants. We used a combination of inclusive and selective quantitative PCR assays that specifically identify variants A19 or B.1.1.7 and tested each sample for the presence and relative viral RNA load of each variant. We show that between December-2020 and March-2021, a complete shift in the SC-2 variant circulation was observed, where the B.1.1.7 replaced the A19 in all examined test points. We further show that the normalized viral load (NVL) values and the average new cases per week reached a peak in January 2021, and then decreased gradually in almost all test points, in parallel with the progression of the national vaccination campaign, during February-March 2021. This study demonstrates the importance of monitoring SC-2 variant dynamics on a national scale through wastewater sampling. It also provides a proof-of-concept methodology for continuous surveillance by using a combination of inclusive and selective PCR tests, which is far more amendable for high throughput monitoring compared with sequencing. This approach may be useful for real-time dynamics surveillance of current and future variants, such as the Omicron (BA.1) variant. SynopsisThis study describes the continuous monitoring of the SARS CoV-2 variant B.1.1.7 circulation in wastewater in Israel using a positive/negative quantitative PCR assay.
Using isolates of SARS-CoV-2 WT, Beta, Delta and most importantly Omicron we studied the capability of the BNT162b2 vaccine given in two or three doses to neutralize major SARS-CoV-2 variants of concern (VOC). We demonstrate low neutralization efficiency against delta and wild-type for vaccines with more than 5 months following the second BNT162b2 dose, with no neutralization efficiency against Omicron. We demonstrate the importance of a third dose, by showing a 100-fold increase in neutralization efficiency of Omicron following a third dose, with a 4-fold reduced neutralization compared to that against the Delta VOC. The durability of the effect of the third dose is yet to be determined.
In this report, we describe four RT-qPCR assays that enable rapid identification of the newly emerging SARS-COV-2 Omicron (B.1.1.529) variant of concern. The assays target Omicron characteristic mutations in the nsp6 (Orf1a), spike and nucleocapsid genes. We demonstrate that the assays are straightforward to assemble and perform, are amendable for multiplexing, and may be used as a reliable first-line tool to identify B.1.1.529 suspected samples. Importantly, this is a preliminary development report. Further validation and optimization of the assays described herein will be published hereafter.
In this report, we describe the development of an RT-qPCR assay, termed Alpha Delta assay, which can detect SARS-COV-2 (SC-2) and distinguish between the Alpha (B.1.1.7) and Delta (B.1.617.2) variants. The Alpha- and Delta-specific reactions in the assay target mutations that are strongly linked to the target variant. The Alpha reaction targets the D3L substitution in N gene, and the Delta reaction targets the spike gene 156-158 mutations. Additionally, we developed a second Delta-specific assay, used as a confirmatory test for the Alpha Delta assay that targets the 119-120 deletion in the Orf8 gene. Both reactions have similar sensitivities of 15-25 copies per reaction, similar to the sensitivity of commercial SC-2 detection tests. The Alpha Delta assay and the Orf8-119del assay were successfully used to classify clinical samples that were subsequently analyzed by whole genome sequencing. Lastly, we show that the Alpha Delta and Orf8-119del assays correctly identified the presence of Alpha and Delta lineages RNA in wastewater samples. This study provides a rapid, sensitive and cost-effective tool for detecting and classifying two worldwide dominant SC-2 variants. It also highlights the importance of a timely diagnostic response to the emergence of new SC-2 variants with significant consequences on global health.
BackgroundIsraeli has vaccinated over 80% of its adult population, with two doses of the Pfizer BNT162b2 vaccine. This intervention has been highly successful in curtailing the coronavirus 2 outbreak. One major concern is the ability of the virus to mutate which potentially can cause SARS-CoV-2 to partially escape from the immune system. Here we evaluate the efficacy of the Pfizer vaccine against the B.1.351 variant. MethodsThe Ministry of Health, initiated sequencing of selected positive swab samples identified as being of interest. We used logistic regression, with variant type as the dependent variable, vaccination status as the main explanatory variable, controlling for age, sex, subpopulation, place of residence and time of sample, to estimate the odds ratio for a vaccinated case to have the B. 1.351 versus the B.1.1.7 variant, within vaccinated and unvaccinated persons who tested positive. FindingsThere were 19 cases of B.1.351 variant (3.2%) among those vaccinated more than 14 days before the positive sample and 88 (3.5%) among the unvaccinated. The estimated odds ratio was 1.29 [95% CI: 0.66-2.50]. From this result, assuming the efficacy against the B.1.1.7 variant to be 95%, the estimated efficacy against the B.1.351 variant was 94% [95% CI: 87-97%]. InterpretationDespite the concerns caused by the B.1.351 variant, the BNT162b2 vaccine seems to provide substantial immunity against both that variant and the B.1.1.7. Our results suggest that from 14 days following the second vaccine dose the efficacy of BNT162b2 vaccine is at most marginally affected by the B.1.351 variant. FundingNo funding
Emerging SARS-CoV-2 variants may threaten global vaccination efforts and awaited reduction in outbreak burden. In this study, we report a novel variant carrying the L452R mutation that emerged from a local B.1.362 lineage, B.1.362+L452R. The L452R mutation is associated with the Delta and Epsilon variants and was shown to cause increased infection and reduction in neutralization in pseudoviruses. Indeed, the B.1.362+L452R variant demonstrated a X4-fold reduction in neutralization capacity of sera from BNT162b2-vaccinated individuals compared to a wild-type strain. The variant infected 270 individuals in Israel between December 2020 and March 2021, until diminishing due to the gain in dominance of the Alpha variant in February 2021. This study demonstrates an independent, local emergence of a variant carrying a critical mutation, L452R, which may have the potential of becoming a variant of concern and emphasizes the importance of routine surveillance and detection of novel variants among efforts undertaken to prevent further disease spread.
Routine detection, surveillance and reporting of SARS-CoV-2 novel variants is important, as these threaten to hinder vaccination efforts. Herein we report a local novel strain that includes a non-synonymous mutation in the spike (S) protein - P681H and additional synonymous mutations. The P681H Israeli strain has not been associated with higher infection rates and was neutralized by sera from vaccinated individuals in comparable levels to the B.1.1.7 strain and a non-P681H strain from Israel.
The changing nature of the corona virus of the SARS-CoV-2 pandemic poses unprecedented challenges to the worlds health systems. New and virulent emerging spike gene variants, such as the UK 20I/501Y.V1 and South African 20H/501Y.V2, could jeopardize global efforts to produce immunity and reduce mortality. These challenges require effective real-time genomic surveillance solutions that the medical community can quickly adopt. The SARS-CoV-2 spike protein mediates host receptor recognition and entry into the cell and therefore, it is most susceptible to generation of variants with increased transmissibility and pathogenicity. The spike protein is also the primary target of neutralizing antibodies in COVID-19 patients and the most common antigen for induction of effective vaccine immunity. Therefore, tight monitoring of the spike protein gene variants is key to mitigating COVID-19 spread and vaccine escape mutants. Currently, the ARTIC method for SARS-CoV-2 whole genome sequencing is applied worldwide. However, this method commonly requires more than 96 hours (4-5 days) from start to finish and at present high sample sequence demands, sequencing resources are quickly exhausted. In this work, we present HiSpike, a method for high-throughput targeted next generation sequencing (NGS) of the spike gene. This simple three-step method can be completed in less than 30 hours and can sequence 10-fold more samples compared to the conventional ARTIC method and at a fraction of the cost. HiSpike was proven valid, and has identified, at high quality, multiple spike variants from real-time field samples, such as the UK and the South African variants. This method will certainly be effective in discovering future spike mutations. Therefore, running HiSpike for full sequencing of the spike gene of all positive SARS-CoV-2 samples could be considered for near real-time detection of known and emerging spike mutations as they evolve. HiSpike provides affordable sequencing options to help laboratories conserve resources, hence it provides a tool for widespread monitoring, that can support critical knowledge-based decisions.
