Volume 25, Number 9—September 2019
Dispatch
Use of Human Intestinal Enteroids to Detect Human Norovirus Infectivity
Table
Comparison of rRT-PCR, HIE, and EIA used to detect human norovirus in samples from 3 patients in Hong Kong
Isolate† | Fold dilution of 1% fecal filtrate | rRT-PCR Ct | HIE (fold change at 72 hpi) | EIA |
---|---|---|---|---|
CUHK-NS-1030 | 3 | 20.9 | + (120) | + |
9 | 22.5 | + (331) | +/– | |
27 | 27.2 | + (85) | – | |
81 | 28.8 | + (23) | – | |
243 | 30.5 | – (ND) | – | |
729 |
32.8 |
– (ND) |
– |
|
CUHK-NS-1127 | 3 | 20.3 | + (4,362) | + |
9 | 22.4 | + (1,436) | + | |
27 | 25.2 | + (781) | + | |
81 | 25.8 | + (200) | – | |
243 | 26.0 | + (43) | – | |
729 | 29.4 | + (61) | – | |
2,187 |
31.8 |
– (ND) |
– |
|
CUHK-NS-1499 | 3 | 25.2 | + (45,793) | + |
9 | 25.5 | + (1,587) | + | |
27 | 26.5 | + (1,094) | – | |
81 | 28.4 | – (ND) | – | |
243 |
30.1 |
– (ND) |
– |
|
*Results for HIE line J2 and the antigen-based RIDASCREEN Norovirus 3rd Generation EIA (R-Biopharm AG, https://clinical.r-biopharm.com) were compared with the rRT-PCR that had been widely used as a standard for clinical diagnostics of norovirus infections. The same amount of fecal filtrate was used in HIE line J2 inoculation and EIA measurement at the indicated dilutions. In HIE, numbers indicated fold changes of norovirus RNA level in culture supernatant at 72 hpi from baseline (1 hpi); an increase of >10-fold was used to confirm the presence of infectious norovirus. Ct, cycle threshold; CUHK, Chinese University of Hong Kong; EIA, enzyme immunoassay; HIE, human intestinal enteroid; hpi, hours postinfection; ND, not detectable; rRT-PCR, real-time reverse transcription PCR; +, positive as defined for each assay; –, negative as defined for each assay; +/–, equivocal as defined according to the manufacturer’s instructions of the EIA. †CUHK-NS-1030, from a 1-year-old boy; CUHK-NS-1127, from a 79-year-old man; CUHK-NS-1499, from a 46-year-old man. |