Enhanced Inactivation of Pseudoparticles Containing SARS-CoV-2 S Protein Using Magnetic Nanoparticles and an Alternating Magnetic Field

Abstract

Severe acute respiratory syndrome coronavirus 2's (SARS-CoV-2) rapid global spread has posed a significant threat to human health, and similar outbreaks could occur in the future. Developing effective virus inactivation technologies is critical to preventing and overcoming pandemics. The infection of SARS-CoV-2 depends on the binding of the spike glycoprotein (S) receptor binding domain (RBD) to the host cellular surface receptor angiotensin-converting enzyme 2 (ACE2). If this interaction is disrupted, SARS-CoV-2 infection could be inhibited. Magnetic nanoparticle (MNP) dispersions exposed to an alternating magnetic field (AMF) possess the unique ability for magnetically mediated energy delivery (MagMED); this localized energy delivery and associated mechanical, chemical, and thermal effects are a possible technique for inactivating viruses. This study investigates the MNPs' effect on vesicular stomatitis virus pseudoparticles containing the SARS-CoV-2 S protein when exposed to AMF or a water bath (WB) with varying target steady-state temperatures (45, 50, and 55 °C) for different exposure times (5, 15, and 30 min). In comparison to WB exposures at the same temperatures, AMF exposures resulted in significantly greater inactivation in multiple cases. This is likely due to AMF-induced localized heating and rotation of MNPs. In brief, our findings demonstrate a potential strategy for combating the SARS-CoV-2 pandemic or future ones.

Keywords: COVID-19; SARS-CoV-2; alternating magnetic field; magnetic nanoparticles; virus inactivation.

Figure 1.

Negative stain TEM image of VSV pseudovirus. Intact bullet shaped particle of VSVΔG-GFP-G measuring ~160 nm × ~80 nm. The roughness around the edges of the particles is likely the not fully resolved structure of G proteins on the pseudoparticle surface.

Figure 2.

Pseudotype system. The VSVΔG-GFP-spike pseudotype system is created using a transient transfection of the SARS-CoV-2 spike protein followed by VSVΔG-GFP-G transduction. This process results in spike surface protein imbedded particles capable of downstream transduction via the ACE2 receptor but cannot propagate. The green fluorescent protein production can then be visualized via fluorescent microscopy. Created using BioRender.com.

Figure 3.

Schematic representation of the overall treatment of MNPs with a WB and AMF to inactivate pseudoparticles containing SARS CoV-2 S protein. Created using BioRender.com.

Figure 4.

Temperature profile and transduction assay at 45 °C. The experiment was replicated three times (N = 3), and the average and standard errors were used for plotting (a) the temperature profile of the sample (0.8 mg/mL MNPs and TNE buffer) in a WB with a set temperature of 45 °C and in an AMF of strength 44.43 kA/m and 292 kHz; (b) the percent transduction of pseudoparticles in a 45 °C water bath (WB) and alternating magnetic field (AMF).

Figure 5.

Temperature profile and transduction assay at 50 °C. The experiment was replicated three times (N = 3), and the average and standard error were used for plotting (a) the temperature profile of the sample (1.2 mg/mL MNPs and TNE buffer) in a WB with a set temperature of 50 °C and in an AMF of strength 44.43 kA/m and 292 kHz; (b) the percent transduction of pseudoparticles in a 50 °C water bath (WB) and alternating magnetic field (AMF).

Figure 6.

Temperature profile and transduction assay at 55 °C. The experiment was replicated three times (N = 3), and the average and standard error were used for plotting (a) the temperature profile of the sample (1.7 mg/mL MNPs and TNE buffer) in a WB with a set temperature of 55 °C and in an AMF of strength 44.43 kA/m and 292 kHz; (b) the percent transduction of pseudoparticles in a 55 °C water bath (WB) and alternating magnetic field (AMF).

Figure 7.

Illustration of the pseudoparticle inactivation mechanism in WB and AMF exposure with MNPs. Created using BioRender.com.