Electromagnetic waves destabilize the SARS-CoV-2 Spike protein and reduce SARS-CoV-2 Virus-Like particle (SC2-VLP) infectivity

Abstract

Infection and transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) continues to pose a global public health concern. Using electromagnetic waves represents an alternative strategy to inactivate pathogenic viruses such as SARS-CoV-2. However, whether electromagnetic waves reduce SARS-CoV-2 infectivity is unclear. Here, we adapted a coplanar waveguide (CPW) to identify frequencies that could potentially neutralize SARS-CoV-2 virus-like particles (SC2-VLPs). Treatment of SC2-VLPs at frequencies between 2.5 and 3.5 GHz and an electric field of 413 V/m reduced infectivity. Exposure of SC2-VLPs to a frequency of 3.1 GHz -and to a lesser extent, 5.9 GHz- reduced their binding to antibodies targeting the SARS-CoV-2 Spike S1 receptor-binding domain (RBD) but did not alter the total levels of Spike, Nucleocapsid, Envelope, or Membrane proteins in virus particles. These results suggest that electromagnetic waves alter the conformation of Spike, thereby reducing viral attachment and entry. Overall, this data provides proof-of-concept in using electromagnetic waves for sanitation and prevention efforts to curb the transmission of SARS-CoV-2 and potentially other pathogenic enveloped viruses.

Keywords: Coplanar waveguide; Electromagnetic waves; SARS-CoV-2; Sanitation; Spike; Transmission.

Fig. 1

Electromagnetic wave hardware setup. (A) Graphical diagram. A computer-controlled function and signal generator produced electromagnetic waves, which were sent to an amplifier and delivered to a TEM cell through N-connector cables. The TEM served as a unit to conduct electromagnetic wave testing, while an oscilloscope was used to detect electrical signals. (B) Image of setup. TEM: transverse electromagnetic cell.

Fig. 2

Coplanar Waveguide (CPW) setup and absorption spectra of SARS-CoV-2 Virus-Like Particles (SC2-VLPs). (A) Illustration of a virus solvent suspended on a CPW. (B) Epirus CPW circuit. (C) SC2-VLP absorption spectra. ΔA reflects the amount of radiation absorbed by SC2-VLPs. RF: Radio-Frequency signal. DUT: Device-Under-Test.

Fig. 3

Electromagnetic waves reduce infectivity of SARS-CoV-2 Virus-Like Particles (SC2-VLPs). (A) Diagram of SC2-VLP production, electromagnetic wave treatment and infectivity assay. Plasmids expressing each of the SARS-CoV-2 structural proteins (Nucleocapsid (N); Matrix (M); Envelope (E); and Spike (S)), or a plasmid encoding a packaging signal and luciferase transcript (Luc-PS9) were transfected into viral producer cells (HEK293T). SC2-VLPs were then collected, left unexposed or exposed to various electromagnetic wave frequencies (1–6 GHz) and used to infect target cells (HEK293T-ACE2-TMPRSS2). The next day, luciferase was measured as a readout of infectivity. Created in https://BioRender.com. (B) Western blot of pelleted Spike (S), Nucleocapsid (N), Membrane (M), Envelope (E) in unexposed virus particles. The image is representative of two independent experiments. (C) SC2-VLP infectivity assay. Frequencies (1–6 GHz) were tested over a range of exposure times (2–10 min). Data represent compiled mean +/- SD of 5 independent experiments. The luciferase signal for each frequency/exposure time was performed in triplicate. P-values indicate Wilcoxon matched-pair signed rank test of unexposed compared to exposed samples. (n = 90 (Unexposed); n = 36 (1.0–2.5 GHz & 2.5–3.5 GHz) n = 15 (3.5–4.8 GHz), n = 33 (4.8–6 GHz), n = 18 (MW)). RLU: Renilla Luciferase Units (RLU). MW: Microwave.

Fig. 4

Electromagnetic waves destabilize SARS-CoV-2 Spike. (A) SC2-VLPs were produced, collected, and either unexposed or exposed to 3.1 or 5.9 GHz electromagnetic waves for 8 min. SC2-VLPs were either subjected to an ELISA to measure binding to antibodies targeting the Spike Subunit 1 receptor-binding domain (S1RBD) or pelleted and probed for Spike (S), Nucleocapsid (N), Membrane (M), and Envelope (E) by western blot. Created in https://BioRender.com. (B) Spike (S1RBD) ELISA. Data represent +/- SD of 2 independent experiments performed in quadruplicate, except for one condition (3.1 GHz) that was analyzed once in quadruplicate and once in triplicate. P-values indicate one-way ANOVA tests of treated compared to untreated samples. (C) Western blot depicting Spike (S), Nucleocapsid (N), Membrane (M), and Envelope (E) within pelleted virus particles. The image is representative of two independent experiments.