EBV DNA IU/mL to Copies/mL Converter
EBV DNA IU/mL to Copies/mL Converter
One laboratory’s own cross-over study found 1 IU/mL of EBV DNA equal to 0.12 copies/mL on the assay it replaced — a more than eightfold gap. That is the only published factor, and this page explains why there are no others.
EBV DNA IU/mL → copies/mL
IU/mL + named assay → copies/mLEBV DNA 2,500 IU/mL in plasma, against ARUP’s cross-over factor of 0.12 copies per IU
The conversion, and how little of it exists
- IU/mL
- international units per mL, calibrated to the 1st WHO International Standard for Epstein-Barr virus (NIBSC 09/260), assigned 5 million IU on reconstitution in 1 mL
- copies per IU
- 0.12 in the only published figure found: ARUP’s verification of its quantitative NAAT against the copies-based assay it replaced. The WHO standard assigns no copy equivalence, and no manufacturer publishes one
- log₁₀ offset
- log₁₀ 0.12, which is −0.92 — nearly a whole log. A copies/mL result and an IU/mL result for one specimen are not the same number to within anything
- 0.30 log₁₀
- the mean difference between two assays that were BOTH calibrated in international units, Abbott RealTime EBV reading lower than the Qiagen artus V1 assay. Standardising the unit did not standardise the number
Worked example
EBV DNA 2,500 IU/mL in plasma, against ARUP's cross-over factor of 0.12 copies per IU
2,500 × 0.12 = 300 copies/mL
log₁₀ 2,500 = 3.40 log₁₀ IU/mL
log₁₀ 300 = 2.48 log₁₀ copies/mL
The offset is −0.92 log₁₀, and it is the same at every viral load
Read the other way, which is the direction a reader usually needs: an old result of 2,500 copies/mL corresponds to 2,500 ÷ 0.12 = 20,833 IU/mL — more than eight times the number, and a rise that never happened if the two are compared raw
Change the assay to any other platform and the result becomes blank rather than a number, because no factor has been published for it
The one published copies-per-IU figure
| Assay | Manufacturer | Copies per IU | IU per copy | What the source prints |
|---|---|---|---|---|
| Epstein-Barr Virus by Quantitative NAAT, Plasma (test 3006079), against its predecessor test 0051352 | ARUP Laboratories | 0.12 | 8.333 | one IU/mL of EBV DNA measured by 3006079 is approximately equal to 0.12 copies/mL reported by 0051352 |
Why an EBV viral load travels badly
| Source of variation | What is documented |
|---|---|
| The WHO standard | NIBSC 09/260 is assigned 5 million IU/mL on reconstitution and no copy equivalence at all |
| Between copies-based and IU-based assays | one laboratory measured 1 IU/mL as about 0.12 copies/mL on the assay it retired — a 0.92 log₁₀ step |
| Between two assays both calibrated in IU/mL | Abbott RealTime EBV read on average 0.30 log₁₀ IU/mL lower than the Qiagen artus V1 assay over 161 quantifiable samples |
| Between specimen types | whole blood, plasma and mononuclear cells give materially different values for the same patient, and no factor relates them |
Monitoring a number that is not comparable with itself
EBV DNA is measured mainly to watch for post-transplant lymphoproliferative disease, which makes it a surveillance test: one patient sampled repeatedly, with the trend carrying the information rather than any single value. Comparability is therefore the whole point, and EBV is unusually bad at it.
Start with the unit. The 1st WHO International Standard for Epstein-Barr virus, NIBSC 09/260, is assigned 5 million international units on reconstitution in a millilitre, and — like the cytomegalovirus and BK virus standards — its instructions for use say nothing about genome copies. That is not an oversight. A copy is whatever a given assay counts, so the relationship is the manufacturer’s to publish, and for EBV essentially none has. The one figure available comes from a reference laboratory’s verification when it moved from a copies-based assay to an IU-calibrated one: 1 IU/mL on the new test corresponded to about 0.12 copies/mL on the old, so the old number was more than eight times the new one for the same specimen. Nearly a full log, from a change of unit.
Then the harder finding. Two assays that both report international units are still not interchangeable. Over 161 quantifiable whole-blood samples the Abbott RealTime EBV assay read on average 0.30 log₁₀ IU/mL lower than the Qiagen artus V1 assay — a twofold difference a shared calibrator did not remove, and large enough that the authors suggested monitoring thresholds might need resetting after a method change. Specimen type adds another layer: whole blood, plasma and mononuclear cells give different values for one patient, and no factor bridges them either.
So the honest use of this page is narrow. It converts between international units and copies for the one laboratory pairing where a factor has been published, and for every other platform returns nothing rather than a plausible invention. A result is comparable only with results from the same assay; a change across platforms is not a change in the patient. What is worth trending is the log change on one assay in one specimen type, which the viral load log change calculator computes; the HCV RNA converter shows what happens when manufacturers do publish factors and disagree sixfold. This supports a clinician’s judgement rather than replacing it: it is arithmetic on the figures entered, and knows nothing about the patient.
Frequently asked questions
What is the conversion factor from EBV IU/mL to copies/mL?
There is essentially none published. The only figure found is a reference laboratory’s cross-over study: 1 IU/mL on its quantitative NAAT corresponded to about 0.12 copies/mL on the assay it replaced. No manufacturer publishes a factor, and the WHO standard assigns no copy equivalence.
Why is the EBV factor so far from 1?
Because a copy and an international unit were never the same quantity, and nothing requires them to be close. The international unit is defined by a vialled WHO material; a copy is whatever a particular assay counts. For that laboratory’s pair of assays the two differed by more than eightfold, a 0.92 log₁₀ step.
Are two EBV assays comparable if both report IU/mL?
Not fully. One comparison of 161 quantifiable samples found the Abbott RealTime EBV assay reading on average 0.30 log₁₀ IU/mL — about twofold — lower than the Qiagen artus V1 assay, despite both being calibrated in international units.
Does it matter whether EBV DNA was measured in whole blood or plasma?
Yes, and more than the unit does. Whole blood, plasma and mononuclear cells give materially different values for one patient, and no conversion factor relates them. Compare like with like, specimen type included.
Which unit should an EBV result be reported in?
IU/mL. It is what current assays issue and what the WHO standard defines, and it is the only unit in which results stand any chance of being compared across laboratories. Copies/mL is legacy.
Related calculators
References
- ARUP Laboratories. Test highlight: Epstein-Barr Virus by Quantitative NAAT, Plasma (3006079), February 2023. (“Results will now be reported in international units (IU) instead of copies”; one IU/mL by 3006079 is approximately 0.12 copies/mL by the predecessor test 0051352.)
- NIBSC. 1st WHO International Standard for Epstein-Barr Virus for Nucleic Acid Amplification Techniques, code 09/260: instructions for use. Potters Bar: National Institute for Biological Standards and Control. (5 × 10⁶ IU on reconstitution in 1 mL; no copy equivalence is assigned.)
- Salmona M, Stefic K, Mahjoub N, et al. Automated quantification of Epstein-Barr virus in whole blood for post-transplant lymphoproliferative disorders monitoring. Virol J. 2020;17:20. doi:10.1186/s12985-020-1285-7
Not medical advice. For healthcare professionals and education. Reference intervals vary by laboratory and assay — always use your own laboratory's. Never base a dose or a treatment decision on this page alone. Full disclaimer at calcengines.com/disclaimer/