Volume 28, Number 7—July 2022
Use of Human Intestinal Enteroids to Evaluate Persistence of Infectious Human Norovirus in Seawater
|0||+||267, 1,082,‡ 103§||+||496||+||1,290||+||639, 600§||+||429, 845§|
|7||+||248, 787‡||+||293||+||476||+||486, 205§||+||3.2, 50§|
|14||+||366, 10,‡ 8.2§||+||31§||+||151§||+||3.2, 0.4§||–||No Ct|
|17||+||6.7, 1,‡ 12§||+||53§||+||139§||–||No Ct||–||No Ct|
|21||+||12, 13,‡ 4.2§||+||70§||+||102§||–||No Ct||–||No Ct|
|24||+||3.1, 15.7,‡ 3.1§||+||3.1§||+||46§||–||No Ct||–||No Ct|
|28||+||0.5, 83,‡ no Ct§||+||213||+||3.7||–||No Ct||–||No Ct|
|31||–||0.7, no Ct‡||+||6.1§||+||16§||–||No Ct||–||No Ct|
|35||–||0.9, 1.0‡||–||0.8§||+||25§||–||No Ct||–||No Ct|
*No ct indicates GMFI could not be calculated because norovirus genome could not be detected by quantitative reverse transcription PCR at 1h or 72h postinfection or both. Ct, cycle threshold; G, genotype; GMFI, geometric mean fold increase; HIE, human intestinal enteroids; Inf, infectious; ND, not done: +, positive (detected); –, negative (not detected). †Each value represents the GMFI in human norovirus genome copies, between 1h and 72h post-infection, in triplicate wells of HIE cultures (n = 3). Evidence of replication was defined as a GMFI >3.0. Freshly prepared and undiluted viral concentrates were used to infect HIE in most experiments and time points, expect for experiment 2 where HIE cultures died after day 7. ‡Fresh viral concentrates diluted 1/10 in culture medium were also used in experiment 1. ¶To assess the possibility to freeze viral concentrates before the HIE infectivity assay, pure viral concentrate stored frozen at −80°C for several weeks and thawed once for culture on HIE were also used in some assays and showed results similar to those with fresh concentrates in 10 out of 11 tests.
1These first authors contributed equally to this article.
2Current affiliation: Centro de Investigaciones Biologicas–Facultade de Bioloxía & CRETUS, Universidade de Santiago de Compostela, Santiago de Compostela, Spain.
3Current affiliation: SECALIM UMR 104 Oniris/Inrae, Nantes, France.