A pyrosequencing protocol for rapid identification of SARS-CoV-2 variants

Identification of SARS CoV‐2 Omicron BA.1 and a novel Delta lineage by rapid methods and partial spike protein sequences in Sulaymaniyah Province, Iraq

Background

Five variants of concern (VOCs) of severe acute respiratory syndrome coronavirus 2 (SARS CoV‐2) have been globally recorded including Alpha, Beta, Gamma, Delta, and Omicron. The Omicron variant has outcompeted the other variants including the Delta variant. Molecular screenings of VOCs are important for surveillance, treatment, and vaccination programs. This study aimed to identify VOCs by using rapid inexpensive methods and partial sequencing of the virus's spike gene.

Methods

Mutation‐specific rRT PCR probes were used for both D614G and K417N mutations to potentially discriminate between Delta and Omicron variants. These were followed by sequencing of a fragment of spike gene (748 nucleotides), which covers the most notable VOC mutations in the receptor binding domain of SARS CoV‐2.

Results

Rapid methods showed that out of 24 SARS CoV‐2 positive samples, 19 carried the N417 mutation, which is present in the Omicron variant. Furthermore, 3 samples carried K417 wildtype, which is present in the Delta variant. Additionally, 2 samples containing both K417 and N417 suggested mixed infections between the two variants. The D614G mutation was present in all samples. Among the 4 samples sequenced, 3 samples carried 13 mutations, which are present in Omicron BA.1. The fourth sample contained the two common mutations (T478K and L452R) present in Delta, in addition to two more rare mutations (F456L and F490S), which are not commonly seen in Delta. Our data suggested that both Omicron variant BA.1 and a novel Delta variant might have circulated in this region that needs further investigations.

Rapid and Sensitive Genotyping of SARS-CoV-2 Key Mutation L452R with an RPA-PfAgo Method

In the two years of COVID-19 pandemic, the SARS-CoV-2 variants have caused waves of infections one after another, and the pandemic is not ending. The key mutations on the S protein enable the variants with enhanced viral infectivity, immune evasion, and/or antibody neutralization resistance, bringing difficulties to epidemic prevention and control. In support of precise epidemic control and precision medicine of the virus, a fast and simple genotyping method for the key mutations of SARS-CoV-2 variants needs to be developed. By utilizing the specific recognition and cleavage property of the nuclease Argonaute from Pyrococcus furiosus (PfAgo), we developed a recombinase polymerase amplification (RPA) and PfAgo combined method for a rapid and sensitive genotyping of SARS-CoV-2 key mutation L452R. With a delicate design of the strategy, careful screening of the RPA primers and PfAgo gDNA, and optimization of the reaction, the method achieves a high sensitivity of a single copy per reaction, which is validated with the pseudovirus. This is the highest sensitivity that can be achieved theoretically and the highest sensitivity as compared to the available SARS-CoV-2 genotyping assays. Using RPA, the procedure of the method is finished within 1.5 h and only needs a minimum laboratorial support, suggesting that the method can be easily applied locally or on-site. The RPA-PfAgo method established in this study provides a strong support to the precise epidemic control and precision medicine of SARS-CoV-2 variants and can be readily developed for the simultaneous genotyping of multiple SARS-CoV-2 mutations.

Diagnostic Tools for Rapid Screening and Detection of SARS-CoV-2 Infection

The novel coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has severely impacted human health and the health management system globally. The ongoing pandemic has required the development of more effective diagnostic strategies for restricting deadly disease. For appropriate disease management, accurate and rapid screening and isolation of the affected population is an efficient means of containment and the decimation of the disease. Therefore, considerable efforts are being directed toward the development of rapid and robust diagnostic techniques for respiratory infections, including SARS-CoV-2. In this article, we have summarized the origin, transmission, and various diagnostic techniques utilized for the detection of the SARS-CoV-2 virus. These higher-end techniques can also detect the virus copy number in asymptomatic samples. Furthermore, emerging rapid, cost-effective, and point-of-care diagnostic devices capable of large-scale population screening for COVID-19 are discussed. Finally, some breakthrough developments based on spectroscopic diagnosis that could revolutionize the field of rapid diagnosis are discussed.