Recovery of Infectious Human Norovirus GII.4 Sydney From Fomites via Replication in Human Intestinal Enteroids.

Joseph Jacangelo,Katie N. Overbey,Kellogg J. Schwab,Caroline Coulter,Nicholas C. Zachos

doi:10.3389/fcimb.2021.693090

Abstract

Contamination of fomites by human norovirus (HuNoV) can initiate and prolong outbreaks. Fomite swabbing is necessary to predict HuNoV exposure and target interventions. Historically, swab recovered HuNoV has been measured by molecular methods that detect viral RNA but not infectious HuNoV. The recent development of HuNoV cultivation in human intestinal enteroids (HIEs) enables detection of infectious HuNoV. It is unknown if the swabbing process and swab matrix will allow for cultivation of fomite recovered HuNoV. We used HIEs to culture swab-recovered HuNoV GII.4 Sydney from experimentally infected surfaces—a hospital bed tray (N = 32), door handle (N = 10), and sanitizer dispenser (N = 11). Each surface was swabbed with macrofoam swabs premoistened in PBS plus 0.02% Tween80. Swab eluate was tested for infectious HuNoV by cultivation in HIE monolayers. Infectious HuNoV can be recovered from surfaces inoculated with at least 105 HuNoV genome equivalents/3 cm2. In total, 57% (N = 53) of recovered swabs contained infectious HuNoV detected by HIEs. No difference in percent positive swabs was observed between the three surfaces at p = 0.2. We demonstrate that fomite swabbing can be combined with the HIE method to cultivate high titer infectious HuNoV from the environment, filling a significant gap in HuNoV detection. Currently, high titers of HuNoV are required to measure growth in HIEs and the HIE system precludes absolute quantification of infectious viruses. However, the HIE system can provide a binary indication of infectious HuNoV which enhances existing detection methods. Identification of infectious HuNoVs from swabs can increase monitoring accuracy, enhance risk estimates, and help prevent outbreaks.

Highlights

Human noroviruses (HuNoVs) are the leading cause of acute gastroenteritis globally and cause significant health and economic burdens (Ahmed et al, 2014)
The pioneering development of an human intestinal enteroids (HIEs) model for culturing infectious HuNoV promises to fill in important gaps around detection of infectious HuNoV particles after recovery from fomites (Ettayebi et al, 2016)
The data shows that the use of swab eluate comprised of phosphate buffered saline (PBS) plus Tween80 does not lead to HIE death or prevent replication of HuNoV GII.4

Summary

Introduction

Human noroviruses (HuNoVs) are the leading cause of acute gastroenteritis globally and cause significant health and economic burdens (Ahmed et al, 2014). HuNoV is spread through the fecal–oral route and virus transmission occurs from person-to-person contact, through aerosolized droplets, and from contact with contaminated fomites (Atmar and Estes, 2006). Fomite-based transmission is of particular concern due to long environmental stability of virus particles and low viral doses required for infection (Otter et al, 2011). There is evidence that fomites can initiate HuNoV outbreaks as well as lead to longer, more severe outbreaks (Weber et al, 2010; Lopman et al, 2012; Repp and Keene, 2012; Canales et al, 2019). HuNoVs recovered from fomites have been detected by recovery of viral RNA with subsequent detection by reverse transcriptionquantitative PCR (RT-qPCR) (Atmar and Estes, 2006; Knight et al, 2013). The advent of novel HuNoV culture methods offer new ways to fill important HuNoV knowledge gaps (Ettayebi et al, 2016)

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