ABSTRACT
Wastewater analysis of pathogens, particularly SARS-CoV-2, is instrumental in tracking and monitoring infectious diseases in a population. This method can be used to generate early warnings regarding the onset of an infectious disease and predict the associated infection trends. Currently, wastewater analysis of SARS-CoV-2 is almost exclusively performed using polymerase chain reaction for the amplification-based detection of viral RNA at centralized laboratories. Despite the development of several biosensing technologies offering point-of-care solutions for analyzing SARS-CoV-2 in clinical samples, these remain elusive for wastewater analysis due to the low levels of the virus and the interference caused by the wastewater matrix. Herein, we integrate an aptamer-based electrochemical chip with a filtration, purification, and extraction (FPE) system for developing an alternate in-field solution for wastewater analysis. The sensing chip employs a dimeric aptamer, which is universally applicable to the wild-type, alpha, delta, and omicron variants of SARS-CoV-2. We demonstrate that the aptamer is stable in the wastewater matrix (diluted to 50%) and its binding affinity is not significantly impacted. The sensing chip demonstrates a limit of detection of 1000 copies/L (1 copy/mL), enabled by the amplification provided by the FPE system. This allows the integrated system to detect trace amounts of the virus in native wastewater and categorize the amount of contamination into trace (<10 copies/mL), medium (10-1000 copies/mL), or high (>1000 copies/mL) levels, providing a viable wastewater analysis solution for in-field use.
Subject(s)
COVID-19 , Water Purification , Humans , COVID-19/diagnosis , SARS-CoV-2/genetics , Wastewater , OligonucleotidesABSTRACT
A unique DNA aptamer, denoted MSA52, displays universally high affinity for the spike proteins of the wild‐type SARS‐CoV‐2 as well as its Alpha, Beta, Gamma, Epsilon, Kappa, Delta and Omicron variants. This aptamer also recognizes pseudotyped lentiviruses expressing eight different spike proteins of SARS‐CoV‐2 with very high affinity, exhibiting dissociation constants (Kd) of 20–50 pM for these viruses. More information can be found in the Research Article by J. D. Brennan, Y. Li et al. (DOI: 10.1002/chem.202200078).
ABSTRACT
Invited for the cover of this issue are Johnâ Brennan, Yingfuâ Li, and co-workers at McMaster University. The image depicts MSA52 as a universal DNA aptamer that recognizes spike proteins of diverse SARS-CoV-2 variants of concern. Read the full text of the article at 10.1002/chem.202200078.
ABSTRACT
We report on a unique DNA aptamer, denoted MSA52, that displays universally high affinity for the spike proteins of wildtype SARS-CoV-2 as well as the Alpha, Beta, Gamma, Epsilon, Kappa, Delta and Omicron variants. Using an aptamer pool produced from round 13 of selection against the S1 domain of the wildtype spike protein, we carried out one-round SELEX experiments using five different trimeric spike proteins from variants, followed by high-throughput sequencing and sequence alignment analysis of aptamers that formed complexes with all proteins. A previously unidentified aptamer, MSA52, showed Kd values ranging from 2 to 10â nM for all variant spike proteins, and also bound similarly to variants not present in the reselection experiments. This aptamer also recognized pseudotyped lentiviruses (PL) expressing eight different spike proteins of SARS-CoV-2 with Kd values between 20 and 50â pM, and was integrated into a simple colorimetric assay for detection of multiple PL variants. This discovery provides evidence that aptamers can be generated with high affinity to multiple variants of a single protein, including emerging variants, making it well-suited for molecular recognition of rapidly evolving targets such as those found in SARS-CoV-2.