Tulane virus disinfection of drinking water by using natural antimicrobials immobilised on silica particles

A batch process, based on a physico-chemical interaction between Tulane virus (TuV) in water and essential oil components immobilised onto silica microparticles (SiO2-EOCs), was investigated. For this purpose, the SiO2-EOCs were uniformly dispersed in the TuV water sample for 2 h. To assess the treatment effectivity, the infectious virus particles and TuV genomic copies (GCs) with and without treatment were quantified by TCID50 and RT-qPCR, respectively. The results indicate that immobilisation of natural antimicrobials markedly increased their antiviral activity. For vanillin and eugenol, the treatment with 20 mg/mL of the functionalised particles reduced TuV infectivity with >5 log10, and with ca. 4 log10 for carvacrol and thymol. The free form of EOCs, however, reduced TCID50 with ca. 1 log10. The RT-qPCR analysis showed an effect beyond TuV entrapment on the functionalised silica particles. RNase treatment of samples prior to RNA extraction and RT-qPCR verified that immobilised EOCs lowered TuV infectivity by reducing the integrity of the virus capsid. These results demonstrate the capacity of the immobilised EOCs to accomplish the stringent disinfection requirements for public water systems.