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

Area of Science:

• Environmental microbiology
• Virology
• Infectious disease epidemiology

Background:

• Human norovirus (HuNoV) outbreaks are often initiated and prolonged by contamination of fomites.
• Current detection methods measure viral RNA, not infectious virus, limiting accurate exposure assessment.
• Human intestinal enteroids (HIEs) offer a novel method for cultivating infectious HuNoV.

Purpose of the Study:

• To determine if fomite swabbing can recover infectious HuNoV suitable for cultivation in HIEs.
• To assess the efficacy of combining fomite swabbing with HIE cultivation for detecting infectious HuNoV.
• To evaluate the potential of this combined method for improving HuNoV outbreak surveillance.

Main Methods:

• Experimentally infected surfaces (bed tray, door handle, sanitizer dispenser) were swabbed using pre-moistened macrofoam swabs.
• Swab eluates were cultured in HIE monolayers to detect infectious HuNoV GII.4 Sydney.
• Infectious virus recovery was assessed from surfaces inoculated with known HuNoV titers.

Main Results:

• Infectious HuNoV was recovered from surfaces with as few as 10⁵ genome equivalents/3 cm².
• Fifty-seven percent of swabs yielded infectious HuNoV detectable by HIE cultivation.
• No significant difference in positive swab rates was observed across the three tested surfaces.

Conclusions:

• Fomite swabbing coupled with HIE cultivation is a viable method for recovering and detecting infectious HuNoV from the environment.
• This approach addresses a critical gap in HuNoV detection, enabling better monitoring and risk assessment.
• The HIE system provides a binary indication of infectious HuNoV, enhancing current detection capabilities for outbreak prevention.