Physicochemical stability profile of Tulane virus: a human norovirus surrogate

Abstract

Based on current work, in vitro studies demonstrate that TV is an overall more conservative and suitable surrogate for the study of HuNoV physicochemical properties.

Thermal Inactivation Kinetics of Tulane Virus in Cell‐Culture Medium and Spinach

“…Unheated virus suspensions in 2‐mL glass vials were used as controls that were kept at room temperature and then placed in an ice water bath for 15 min. Ten‐fold serial dilutions of the virus were carried out in Opti‐MEM (containing 2% FBS and 1% antibiotic‐antimycotic) and enumerated by plaque assays using confluent LLC‐MK2 cells in six‐well plates (Arthur & Gibson, ).…”

“…Enumeration of TV was carried out using modifications of previously described protocols (Arthur & Gibson, ). Briefly, 500 μL of aliquots of the dilutions of heat‐treated or untreated virus were added on to confluent LLC‐MK2 host cells in six‐well plates, allowed to infect for 3 hr at 37 °C with 5% CO 2 before overlaying with media comprising of Opti‐MEM (containing 2% FBS and 1% antibiotic‐antimycotic) in 1.5% Noble agar (Difco Agar Noble, BD, Sparks, MD).…”

“…FCV‐F9 was found to be the most sensitive to bleach among the three tested viruses (MNV‐1 and TV being the other two) that showed 5.3 log PFU/mL reduction under the same treatment conditions (Cromeans et al., ). Although Arthur and Gibson () showed that TV on a solid surface was resistant to aqueous chlorine treatments of 200 and 1,000 ppm with D ‐values of 15.82 and 5.42 min, respectively (slightly more resistant than reported by Cromeans et al., ), others showed that MNV‐1 was more stable to pH 2, 9, and 10 compared to TV (Hirneisen & Kniel, ).…”

“…TV and MNV‐1 showed <0.5 log PFU/mL (PFU—plaque forming unit) reduction in infectivity in 100 mM citric acid (pH 2) and only approximately 2 log PFU/mL reduction in 100 mM carbonate buffer (pH 10) after 30 min at 37 °C, whereas FCV‐F9 titers were reduced to nondetectable levels at both pH 2 and pH 10 under the same conditions (Cromeans et al., ). Other researchers showed that <l log PFU/mL reduction of TV was obtained at pH 2, 3, 7, and 9 after 90 min at RT, whereas pH 10 resulted in 2.25 log PFU/mL reduction after 90 min at RT (Arthur & Gibson, ).…”

“…Cultivable TV was not available when these previous studies were undertaken in our laboratory (Bozkurt, D'Souza, & Davidson, , , ; Bozkurt, Ye, Harte, D'Souza, & Davidson, ). Although studies have been performed to analyze the thermal inactivation of TV in cell‐culture media, only 1.5 mL centrifuge tubes (Arthur & Gibson, ; Tian et al., ) or 0.2 mL PCR tubes (Hirneisen & Kniel, ), or more recently, capillary tubes (Araud et al., ), were used. The heat‐inactivation kinetics of TV in 2‐mL glass vials (using different glass container sizes compared to glass capillary tubes) as well as the z ‐values have not been reported to date.…”