Limit of blank (LOB)
The LOB is defined as the highest measurement result that is likely to be observed for a blank sample. For this kit, the cycle threshold (Ct) value in the Test Channel was considered an appropriate LOB. The Ct value of negative samples should remain above a threshold value (45) to generate a result “not detected”. A separate LOB was established for influenza A and influenza B on 61 measurements across two reagent lots. For influenza A-H1, the LOB was established on 67 measurements across 2 regional lots.
Limit of detection (LOD)
The LOD of the artus Infl. A/B/H1 QS-RGQ Kit was established for the 3 targeted analyte strains included in the kit, i.e., influenza A/H3N2 (A/Marseille/90454111/2011), influenza B/Yamagata (B/Marseille/74506131/2013), and influenza A/H1N1 (A/Marseille/4590681204/2014 [season 2013-2014]).
|AB ||A/H3N2 ||3.82 x 10-2 |
|AB ||A/H1N1 ||1.75 x 10-2 |
|AB ||B ||2.16 x 10-2 |
|H1 ||A/H1N1 ||3.97 x 10-4 |
The analytical cross-reactivity of the artus Infl. A/B/H1 QS-RGQ Kit was evaluated by testing a panel of 40 commonly co-infected pathogens at clinically relevant concentrations. The analytical reactivity of the artus Infl. A/B/H1 QS-RGQ Kit was assessed against 11 influenza A strains and 9 influenza B strains. Results showed no evidence of cross-reactivity and confirmed the reactivity of all 20 influenza strains tested.
Carryover and cross-contamination
These studies were conducted with contrived samples obtained by diluting Influenza A/Marseille/58863121/2012 (H1N1) strain in virocult for positive samples and virocult only for negative samples with Influenza AB and H1 Masters.
There was no evidence of carryover or intra-run contamination.
Repeatability and reproducibility
Repeatability and reproducibility of the artus Infl. A/B/H1 QS-RGQ Kit were determined using single site and multi-site studies using 2 different viral strains, Infl. B/Yamagata (B/Marseille/74506131/2013) and Infl. A/H1N1 (A/Marseille/4590681204/2014) as circulating in season 2013-2014. Single site studies showed there was no Rotor-Gene Q instrument nor batch effect except for assay A of the Influenza AB Master where a batch effect was observed when the sample was at low concentrations. Multi-site studies confirmed there were no QIAsymphony Sample Preparation (SP) - Assay Setup (AS) modules and site effects.
The effect of potentially interfering substances was determined in accordance with CLSI guidelines EP07-A2 (1). This included endogenous substances (e.g., mucin, blood) and exogenous substances (e.g., fluticasone, menthol, muciprocin, oseltamivir, oxymetazoline, phenylephrine, saline, tobramycin). The concentrations at which these substances are unlikely to interfere with the assay can be found in the kit handbook.
A total of 202 human nasal swab specimens were tested with the artus Infl. A/B/H1 QS-RGQ Kit and the results compared with those obtained previously using laboratory developed tests derived from published method (1) at the University of Marseille, France. RNA was extracted on the QIAsymphony SP using a single batch of QIAsymphony DSP Virus/Pathogen Midi Kit. The RT-qPCR plates were set-up with a single QS-AS module using one reagent lot of the artus Infl. A/B/H1 QS-RGQ Kit. Discrepant results were resolved by testing samples with a third method, the GeneXpert Xpert Xpress Flu/RSV (Cepheid) according to protocols at the University of Marseille, France.
Further information on the performance characteristics of this kit are provided in kit handbook, which can be downloaded from the Resources tab on this webpage.
World Health Organization (July 2017). WHO information for the molecular detection of influenza viruses. Available at: