Retention of Tulane Virus and Murine Norovirus by Zero-Valent Iron Treated by Various Elution Buffers

Introduction: Removal of Tulane virus (TV) and murine norovirus (MNV) from water filtered through sand with zero-valent iron (ZVI) has been demonstrated. ZVI has been proposed to interact with viruses through electrostatic forces.

Purpose:  Reversibility of ZVI retention of TV and MNV from water was investigated by viral elution with various buffers.

Methods: TV and MNV in deionized water (0.5 ml, 4 and 5 log PFU/ml, respectively) were exposed to sand and ZVI:sand (1:1) (1 cm³) in tubes for 30 minutes at 21°C in duplicate. Inoculants were aspirated; sand and ZVI:sand were agitated for 30 minutes in water or elution buffer (citrate buffer, pH 4 and 7, and virus elution buffer, pH 9.5, with and without added 1M NaCl). TV and MNV in the eluates were tested by plaque assay in LLCMK2 and RAW 264.7 cells, respectively. Positive and negative controls were included for eluents and water rinsates of sand and ZVI:sand.

Results: Recovery of TV from treated water was 3.7 and 2.6 log PFU/ml from sand and ZVI:sand, respectively. Eluted TV averaged 3.4 log PFU/ml (sand) and 1.9 log PFU/ml (ZVI:sand). Recovery of MNV from treated water was 4.6 and 3.6 log PFU/ml from sand and ZVI:sand, respectively. Eluted MNV averaged 4.3 log PFU/ml (sand) and 3.1 log PFU/ml (ZVI:sand). Virus retention by ZVI:sand was significantly (P<0.05) greater than sand alone. There were no significant differences (P>0.05) in elution of infectious virus.

Significance:  Comparable recovery of TV and MNV by water and buffers suggests viruses are inactivated by ZVI or viral dissociation from ZVI requires disruption of additional interactions by strategies other than those normally used to recover virus from environmental samples. These data further support the potential efficacy of ZVI for remediation of viral-contaminated water.