Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011

Wolf, S; 2007 134

Diagnostic study

2,3

To evaluate a multiplex real-time RT-PCR that distinguishes between norovirus genogroups I, II, and III and targets the junction between open reading frames 1 and 2 compared to Kageyama real time RT-PCR.              

Real time RT-PCR assays evaluated against 45 RNA samples collected from 2001-2006 known to be positive for norovirus including:
34 human stool samples from New Zealand
6 raw and 3 treated sewage samples
Single samples of contaminated drinking water and source water.

28 stool samples collected from asymptomatic cattle in May 2006 from farms in New Zealand.

Positive results
Multiplex real time RT-PCR positive for norovirus GI/1, GI/2, GI/3, GI/4, GI/5, GI/6, G1/7, GII/8, GII/10, GII/12, and GII/17 in different matrices (stool samples, treated and raw sewage, source water, and treated drinking water).

Agreement between the multiplex real time RT-PCR vs. Kageyama real time RT-PCR
All samples positive by Kageyama RT-PCR also positive by multiplex RT-PCR.
norovirus GI – 2/25 (8%) negative by Kageyama RT-PCR positive by multiplex RT-PCR.
norovirus GII –  3/17 (18%) negative by Kageyama RT-PCR positive by multiplex RT-PCR.

Cycle threshold (CT) values
In 16/20 norovirus GI samples and 26/28 norovirus GII samples positive by both assays, CT values for the multiplex assay were on average -2.4 CT U lower than for the Kageyama assay.

Remaining 6 samples had higher CT  values using the multiplex assay:
3/3 GI/3 specimens, on average +3.9 CT  U
1/1 GI/7 specimen, +3.5 CT U
1/1 GII/1 specimen, +3.3 CT U
1/1 GII/12, +1.4 CT U 

Level of detection
Multiplex real-time RT-PCR detects <10 copies/reaction of norovirus GI/1, GII/3, and GIII/1 N/A. Calculated efficiency values of the assay were 0.93, 0.90, and 1.04 based on the slopes of the standard curves of 3.59, 3.60, and 3.23.

Kageyama real time RT-PCR compared to the multiplex real time RT-PCR.

A new bovine NLV, Bo/NLV/Norsewood/2006/NZL was identified using multiple real-time RT-PCR.

068_IL

Trujillo, A; 2006 18

Diagnostic study

2

To compare the test characteristics of Taqman RT-PCR with conventional RT-PCR for th edetection of GI, GII and GIV strains                                         

Stool specimens from sporadic cases and outbreaks of gastroenteritis. Water samples from outbreaks of gastroenteritis in the US.

92 stool samples and 33 water samples

Test characteristics of Taqman RT-PCR vs. conventional RT-PCR
Stool specimens
TP – 65
TN – 27
FP – 0
FN – 0

By means of serially diluted norovirus RNA transcripts, a potential detection limit of < 10 transcript copies per reaction mixture was observed with the GII assay and a potential detection limit of < 10 transcript copies per reaction mixture was observed with the GI assay.

Water specimens
8/33 specimens were found to be positive. No test characteristics were reported

Power and sample size not reported

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Concentration method

Beuret, C; 2003146

Diagnostic study

None

To test a method for concentration of enteric viruses from water, whereby viruses are directly lysed after filtration on a negatively charged membrane. This method does not have the rinsing, elution, centrifugation and flocculation steps used in older protocols.                                                    

Water samples. Study was conducted in Switzerland.

Not reported

Detection limit
A sensitivity of a 106 fold dilution could be detected for norovirus which compared favorably to the older protocol

Power and sample size not reported

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