Available online 8 November 2022, 105325
Highlights•High titer stocks of Hepatitis E virus were produced using cell culture systems
•Two secondary standards were calibrated against the WHO IS in a Collaborative Study
•The secondary standards are non-infectious and stable
•These standards are useful for interlaboratory harmonization of HEV NAAT assays
ABSTRACTBackgroundTo harmonize assays for detection of HEV RNA, a World Health Organization International Standard (WHO IS) was established. The WHO IS represents the highest order standard for HEV RNA but is limited in quantity. Secondary standards are needed to limit the use of WHO IS and minimize the need to replace it.
ObjectiveEstablish secondary standards for HEV NAAT assays and to calibrate these against the WHO IS.
MethodsStocks of genotype 3 HEV were prepared using both cell lysates and cell culture supernatants to produce non-enveloped and quasi-enveloped virus stocks, respectively. Both stocks were heat-inactivated, diluted in negative human plasma, and lyophilized to produce two candidate secondary standards: HEV-RR (non-enveloped virus) and HEV-RR.1 (quasi-enveloped virus). Both candidate standards were characterized and calibrated against the WHO IS for HEV RNA in an international collaborative study.
ResultsThe collaborative study returned a total of 15 data sets, with different RNA extraction and amplification methods. The estimated mean values relative to the WHO IS (250,000 IU/ml) are 229,000 IU/ml and 355,000 IU/ml for HEV-RR and HEV-RR.1, respectively.
ConclusionWe have established two secondary standards for HEV RNA calibrated against the WHO IS. These standards are non-infectious and stable under different storage temperatures.
KeywordsSecondary standards
Hepatitis E virus
Nucleic acid tests
Standardization
Molecular testing
Biological standards
Published by Elsevier B.V.
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