Dataset Information

Quantitative norovirus viral load is not affected by home storage of stool.

ABSTRACT: In preparation of a clinical trial of norovirus treatment, there were concerns raised by FDA about risk of self-storage of stool from patients infected with norovirus affecting quantitative assessments of norovirus RNA. Specifically, most home freezers are frost-free and may expose the samples to multiple rounds of freeze-thaw. Stool samples collected by the study team were stored at different lengths in a frost-free freezer and at -80°C. Quantitative PCRs of norovirus were performed on all samples using the same assay. By all measures, there was no significant change in measured viral load with home storage.

SUBMITTER: Ison MG

PROVIDER: S-EPMC9233081 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Quantitative norovirus viral load is not affected by home storage of stool.

Ison Michael G MG Tan Ming M Daud Amna A Huang Pengwei P Jiang Jason Xi JX

Transplant infectious disease : an official journal of the Transplantation Society 20220401 3

In preparation of a clinical trial of norovirus treatment, there were concerns raised by FDA about risk of self-storage of stool from patients infected with norovirus affecting quantitative assessments of norovirus RNA. Specifically, most home freezers are frost-free and may expose the samples to multiple rounds of freeze-thaw. Stool samples collected by the study team were stored at different lengths in a frost-free freezer and at -80°C. Quantitative PCRs of norovirus were performed on all samp ...[more]

PMID: 35334150

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Project description:BACKGROUND: Reverse transcription-polymerase chain reaction (RT-PCR) is the main method for laboratory diagnosis of norovirus-associated infectious intestinal disease (IID). However, up to 16% of healthy individuals in the community, with no recent history of IID, may be RT-PCR positive; so it is unclear whether norovirus is actually the cause of illness in an IID case when they are RT-PCR positive. It is important to identify the pathogen causing illness in sporadic IID cases, for clinical management and for community based incidence studies. The aim of this study was to investigate how faecal viral load can be used to determine when norovirus is the most likely cause of illness in an IID case. METHODS: Real-time RT-PCR was used to determine the viral load in faecal specimens collected from 589 IID cases and 159 healthy controls, who were infected with genogroup II noroviruses. Cycle threshold (Ct) values from the real-time RT-PCR were used as a proxy measure of viral load. Receiver-operating characteristic (ROC) analysis was used to identify a cut-off in viral load for attributing illness to norovirus in IID cases. RESULTS: One hundred and sixty-nine IID cases and 159 controls met the inclusion criteria for the ROC analysis. The optimal Ct value cut-off for attributing IID to norovirus was 31. The same cut-off was selected when using healthy controls, or IID cases who were positive by culture for bacterial pathogens, as the reference negative group. This alternative reference negative group can be identified amongst specimens routinely received in clinical virology laboratories. CONCLUSION: We demonstrated that ROC analysis can be used to select a cut-off for a norovirus real time RT-PCR assay, to aid clinical interpretation and diagnose when norovirus is the cause of IID. Specimens routinely received for diagnosis in clinical virology laboratories can be used to select an appropriate cut-off. Individual laboratories can use this method to define in-house cut-offs for their assays, to provide the best possible diagnostic service to clinicians and public health workers. Other clinical and epidemiological information should also be considered for patients with Ct values close to the cut-off, for the most accurate diagnosis of IID aetiology.

Dataset Information

Quantitative norovirus viral load is not affected by home storage of stool.

Publications

Quantitative norovirus viral load is not affected by home storage of stool.

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