Diagnosing rotavirus A associated IID: Using ELISA to identify a cut-off for real time RT-PCR

Gemma Phillips*, Ben Lopman, Clarence C. Tam, Miren Iturriza-Gomara, David Brown, Jim Gray

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)


Background: The use of RT-PCR for diagnosis of group A rotaviruses is increasing, but up to 14% of healthy individuals may be positive by RT-PCR. If RT-PCR is not well correlated with disease, rotavirus A may not always be the cause of illness in RT-PCR positive patients with infectious intestinal disease (IID). Objectives: To describe the differences in faecal viral load between ELISA positive IID cases, RT-PCR positive cases and healthy controls. To develop a cut-off in faecal viral load for attributing illness to rotavirus A in RT-PCR positive IID cases. Study design: Faecal viral load was measured, using real time RT-PCR, in 118 community IID cases and 65 healthy controls, previously tested by ELISA. Cycle threshold (Ct) values from the real-time RT-PCR were used as a proxy measure of viral load. A cut-off for attributing illness to rotavirus A was selected, using ROC analysis. Results: There was little overlap in viral load between ELISA positive IID cases (median Ct 17) and healthy controls (median Ct 37), but ELISA negative, RT-PCR positive IID cases (median Ct 37) had viral loads similar to healthy controls, indicating that RT-PCR is not detecting extra cases of group A rotavirus associated IID, only sub-clinical infections. The optimal cut-off in the real time RT-PCR was at Ct value 24-27. Conclusion: ELISA is the best method for the laboratory diagnosis of rotavirus A associated IID. If RT-PCR is used, it is advisable to use a real time platform and to use a viral load cut-off equivalent to the detection limit of ELISA.

Original languageEnglish
Pages (from-to)242-245
Number of pages4
JournalJournal of Clinical Virology
Issue number3
Publication statusPublished - Mar 2009

Bibliographical note

Funding Information:
This study was funded by the Food Standards Agency. We would like to thank Corrine Amar, Fenella Halstead, Dalia Choudhury and Mihaela Cirdei who completed the laboratory testing.


  • Aetiology
  • Asymptomatic
  • RT-PCR
  • Rotavirus A
  • Viral load


Dive into the research topics of 'Diagnosing rotavirus A associated IID: Using ELISA to identify a cut-off for real time RT-PCR'. Together they form a unique fingerprint.

Cite this