A fast and cheap in-house magnetic bead RNA extraction method for COVID-19 diagnosis

Phenol-free in-house kit for RNA extraction with applicability to SARS-CoV-2 genomic sequencing studies: A contribution to biotechnological sovereignty in Colombia

During the COVID-19 pandemic, reagents for SARS-CoV-2 detection were scarce or sold at high prices, particularly in Latin America. In this study, a significant step towards self-sufficiency was achieved through the development of an in-house extraction kit for detecting SARS-CoV-2 from nasopharyngeal swab samples. The purity and concentration of the RNA extracted using the in-house kit were compared to those obtained using the GeneJET RNA Purification Kit (Thermo-Scientific®) as a reference. The applicability of the RNA extracted using the kit was evaluated using four samples positive for SARS-CoV-2 by NGS sequencing with Illumina®. There were no significant differences between the results obtained with the in-house kit and those obtained with the commercial kit. These findings confirm that the in-house protocol demonstrated satisfactory diagnostic accuracy for detecting the virus in patients with COVID-19. The in-house extraction kit works effectively, providing optimal RNA extraction for genomic characterization and lineage assignment of SARS-CoV-2 within the four positive samples analyzed. This phenol-free kit represents a local design and production achievement, offering an effective solution for RNA extraction and detection and sequencing of SARS-CoV-2 from nasopharyngeal swabs. The data highlight the essential contribution of this study to health and biotechnological sovereignty in Colombia.

Simultaneous Extraction of Bone Marrow RNA and DNA from Patients with Hematologic Diseases Using a Combined Magnetic Bead Method within 1 Hour

BACKGROUND

TRIzolTM is widely used for RNA and DNA extraction. However, this method is laborious and time-consuming. The objective of this study was to validate a time-effective and labor-saving protocol.

METHODS

The TRIzol method was used to separate the aqueous phase, protein, and phenol layer of bone marrow samples from 12 patients with hematological diseases. Subsequently, RNA and DNA were extracted from the aqueous layer containing RNA and phenol layer containing DNA, respectively, using magnetic bead extraction kits. The quantity and purity of extracted RNA and DNA were examined using a NanoDrop spectrophotometer. Quantitative fluorescence PCR amplification of the ABL1 gene was performed to verify the effectiveness of the extracted RNA and DNA for downstream experiments. RNA and DNA from another 16 bone marrow samples were extracted to compare the performance of the two methods.

RESULTS

Co-extraction of RNA and DNA was completed within 1 h. The data showed that RNA and DNA yield ranged from 13.1 to 204.5 ng/µL and 33.1 to 228.8 ng/µL, respectively. The A260/A280 ratios of RNA and DNA samples ranged from 1.82 to 2.01 and 1.73 to 1.91, respectively. RNA and DNA extracted using this scheme exhibited ideal performance in quantitative fluorescence PCR. The present protocol showed better quality and effectiveness in extracting RNA and DNA compared to the TRIzol method.

CONCLUSIONS

This protocol for RNA and DNA co-extraction is fast, labor-saving, and high throughput. It can be adopted for routine molecular biology analyses, particularly for non-reproducible specimens.

Overview of the different methods for RNA preparation in COVID-19 diagnosis process during the pandemic

The COVID-19 pandemic brought to light the impact of a widespread disease on various aspects of human relationships, communities, and economies. One notable consequence was the increased demand for diagnostic kits, laboratory reagents, and personal health equipment. This surge in testing capacity worldwide led to shortages in the supply of essential items, including RNA extraction kits, which are crucial for detecting COVID-19 infections. To address this scarcity, researchers have proposed alternative and cost-effective strategies for RNA extraction, utilizing both chemical and physical solutions and extraction-free methods. These approaches aim to alleviate the challenges associated with the overwhelming number of tests being conducted in laboratories. The purpose of this review is intends to provide a comprehensive summary of the various kit-free RNA extraction methods available for COVID-19 diagnosis during the pandemic.

Silica-coated magnetic particles for efficient RNA extraction for SARS-CoV-2 detection

Molecular diagnostic methods to detect and quantify viral RNA in clinical samples rely on the purification of the genetic material prior to reverse transcription polymerase chain reaction (qRT-PCR). Due to the large number of samples processed in clinical laboratories, automation has become a necessity in order to increase method processivity and maximize throughput per unit of time. An attractive option for isolating viral RNA is based on the magnetic solid phase separation procedure (MSPS) using magnetic microparticles. This method offers the advantage over other alternative methods of making it possible to automate the process. In this study, we report the results of the MSPS method based on magnetic microparticles obtained by a simple synthesis process, to purify RNA from oro- and nasopharyngeal swab samples of patients suspected of COVID-19 provided by three diagnostic laboratories located in the Buenos Aires Province, Argentina. Magnetite nanoparticles of Fe3O4 (MNPs) were synthesized by the coprecipitation method and then coated with silica (SiO2) produced by hydrolysis of tetraethyl orthosilicate (TEOS). After preliminary tests on samples from the A549 human lung cell line and swabs, an extraction protocol was developed. The quantity and purity of the RNA obtained were determined by gel electrophoresis, spectrophotometry, and qRT-PCR. Tests on samples from naso- and oropharyngeal swabs were performed in order to validate the method for RNA purification in high-throughput SARS-CoV-2 diagnosis by qRT-PCR. The method was compared to the spin columns method and the automated method using commercial magnetic particles. The results show that the method developed is efficient for RNA extraction from nasal and oropharyngeal swab samples, and also comparable to other extraction methods in terms of sensitivity for SARS-CoV-2 detection. Of note, this procedure and reagents developed locally were intended to overcome the shortage of imported diagnostic supplies as the sudden spread of COVID-19 required unexpected quantities of nucleic acid isolation and diagnostic kits worldwide.

Salmonella detection with LAMP and qPCR and identification of serovars of interest by multiplex qPCR in poultry carcasses

Salmonella is present in the poultry production chain and is a major challenge in terms of food safety and animal health. The early Salmonella detection is one of the main tools to control and prevent the transmission of this pathogen. Microbiological isolation and serotyping to identify and differentiate Salmonella serovars are laborious processes, time-consuming, and expensive. Therefore, molecular diagnostic methods can be rapid and efficient alternatives to the detection of this pathogen. Thus, the aim herein was to standardize and evaluate the use of loop-mediated isothermal amplification (LAMP) in comparison with real-time PCR (qPCR) for detection of Salmonella associated with a multiplex qPCR for simultaneous identification and differentiation of S. Enteritidis, S. Typhimurium, S. Pullorum, and S. Gallinarum. The LAMP, qPCR, and multiplex qPCR assays were comparable in specificity. The three techniques were evaluated for specificity for 16 different serovars of Salmonella and for 37 strains of the serovars of interest. The limit of detection and the efficiency of the LAMP, qPCR, and multiplex qPCR reactions were determined. The techniques were applied to 33 samples of chicken carcasses and compared to the results of conventional microbiology for validation. As results, LAMP was specific in the detection of different Salmonella serovars but presented lower limit of detection ranging from 101 to 104 CFU/reaction. In comparison, qPCR could detect less cells (100 to 102 CFU/reaction), reaching equal specificity and better repeatability in the assays. The qPCR multiplexing for identification of the different serovars also showed good specificity, with the detection threshold between entre 101 and 102 CFU/reaction. The results obtained in the analyses on poultry carcasses suggested a correspondence between the results obtained in molecular methods and in conventional microbiology. Thus, the proposed assays are promising for the diagnosis of Salmonella in poultry carcasses, already proved to be faster and more efficient than conventional diagnostics techniques, being of great interest for poultry production, animal, and public health.

Developing novel liquid biopsy by selective capture of viral RNA on magnetic beads to detect COVID-19

Objectives

Early, specific, and sensitive detection methods of COVID-19 are essential for force stopping its worldwide infection. Although CT images of the lung and/or viral RNA extraction followed by real-time reverse-transcriptase-polymerase chain reaction (rRT-PCR) are widely used; they have some limitations. Here, we developed a highly sensitive magnetic bead-based viral RNA extraction assay followed by rRT-PCR.

Materials and Methods

Case group included oropharyngeal/nasopharyngeal and blood samples from 30 patients diagnosed positive by PCR test for COVID-19 and control group included 30 same samples from COVID-19 negative PCR test individuals. RNA was extracted, using viral RNA extraction kit as well as using our hand-made capture bead-based technique. A one-step cDNA synthesis and Real Time PCR was conducted. A two-step comparison of the different viral RNA extraction methods for oropharyngeal/nasopharyngeal and blood samples was performed. Student t-test was applied with a P<0.05 considered statistically significant.

Results

In the case group, all 30 mucosal samples extracted either with viral RNA extraction kit or with beads-based assay were COVID-19 positive although in the latter category, Cqs were much lower. Although 43% of plasma samples extracted by bead-based method were found to be positive but no plasma samples extracted with column-based kit were detected positive by Real Time PCR.

Conclusion

Bead-based RNA extraction method can reduce RNA loss by its single-tube performance and enhance the test sensitivity. It is also more sensitive to lower viral loads as shown in the detection of blood samples and the lower Cqs of mucosal samples.