Evaluating the capacity of magnetic ionic liquids for separation and concentration of non-enveloped viral particles and free viral genomic RNA

Magnetic ionic liquids (MILs) have proven effective as capture reagents for foodborne bacterial pathogens; however, there are currently no published studies regarding their use with foodborne, non-enveloped viruses. In this study, a protocol was evaluated for capture and recovery of bacteriophage MS2, a human norovirus surrogate, and purified viral genomic single stranded RNA (ssRNA) from an aqueous suspension using MILs. Transition metal-based MILs showed similar capture and recovery efficiency for both targets. A rare earth metal-based MIL showed much greater capture efficiency than the transition metal-based MILs, but displayed similar recovery. All tested MILs showed slightly higher capture and recovery efficiency for free RNA in comparison to intact virus, though overall trends were similar, and most MILs could recover both targets at as little as 10² PFU/mL intact MS2 or copies/mL purified RNA. A plaque assay confirmed that contact with MILs did not significantly reduce viral infectivity. Adjusting MIL volume gave no significant changes in capture or recovery, likely due to interplay between volume for the hydrophobic MIL and dispersion. Reducing the elution volume gave a slight increase in recovery, indicating MILs could be used for target enrichment after further optimization. MILs could also capture MS2 from romaine lettuce rinsate at comparable or even higher levels than from pure suspension, though loss in recovery was observed when the rinsate was prepared in an alkaline elution buffer. Overall, these results demonstrate the potential utility of MILs as concentration reagents for foodborne viruses, particularly for in-field applications.