Comparison of different approaches to quantitative adenovirus detection in stool specimens of hematopoietic stem cell transplant recipients

- Standardized adenovirus DNA isolation/qPCR is necessary for successful theranostics.
- Different DNA isolations have more influence on quantitative virus analysis than PCRs.
- Amplification efficiencies differ for adenoviral species by different PCR assays.
- Dynamic range is between 103 and 108 copies/g stool for both PCR assays.

BackgroundAdenoviruses almost invariably proliferate in the gastrointestinal tract prior to dissemination, and critical threshold concentrations in stool correlate with the risk of viremia. Monitoring of adenovirus loads in stool may therefore be important for timely initiation of treatment in order to prevent invasive infection.ObjectivesComparison of a manual DNA extraction kit in combination with a validated in-house PCR assay with automated extraction on the NucliSENS-EasyMAG device coupled with the Adenovirus R-gene kit (bioMérieux) for quantitative adenovirus analysis in stool samples.Study designStool specimens spiked with adenovirus concentrations in a range from 10E2-10E11 copies/g and 32 adenovirus-positive clinical stool specimens from pediatric stem cell transplant recipients were tested along with appropriate negative controls.ResultsQuantitative analysis of viral load in adenovirus-positive stool specimens revealed a median difference of 0.5 logs (range 0.1-2.2) between the detection systems tested and a difference of 0.3 logs (range 0.0-1.7) when the comparison was restricted to the PCR assays only. Spiking experiments showed a detection limit of 102-103adenovirus copies/g stool revealing a somewhat higher sensitivity offered by the automated extraction. The dynamic range of accurate quantitative analysis by both systems investigated was between 103 and 108 virus copies/g.ConclusionsThe differences in quantitative analysis of adenovirus copy numbers between the systems tested were primarily attributable to the DNA extraction method used, while the qPCR assays revealed a high level of concordance. Both systems showed adequate performance for detection and monitoring of adenoviral load in stool specimens.