COMPARISON OF DIAGNOSTIC HYBRIDS D3 DUET (RSV AND INFLUENZA), D3 DOUBLE DUET AND D3 ULTRA DFA SCREENING REAGENTS FOR THE DETECTION OF 8 RESPIRATORY VIRUSES IN DIRECT SPECIMENS

Introduction: The rapid detection of respiratory viruses by direct immunofluorescence (DFA) has a significant impact on the management and treatment of patients. Currently in the HRLMP Regional Virology laboratory, nasal pharyngeal swabs (NPS) are routinely screened for Parainfluenza Virus 1, 2, 3, Influenza A and B, Respiratory Syncytial Virus (RSV), Adenovirus and Human Metapneumovirus (MPV) with the D³ Ultra respiratory reagents. DHI has several other commercial kits for rapid detection of respiratory viruses available including: 1) D³ Duet DFA RSV/ Respiratory Virus screening reagent (DR) which differentiates RSV from others , 2) the D³ Duet DFA Influenza A/ Respiratory Virus screening reagent (DIA) (which differentiates Flu A from others, and 3) the D³ Double Duet(DD)* DFAKit^TM (The DR and DIA reagents are available in the US, Canada and world wide, but currently FDA cleared for culture use only.  The *DD is currently available only outside the United States).  The “ex US” DD respiratory screening kit consists of control slides, mounting fluid, PBS and two reagent vials – one vial that detects Influenza A and differentiates it from Influenza B, Parainfluenza 1, 2, 3 and Adenovirus (which are not differentiated) and the second reagent vial for the detection and differentiation of   RSV/MPV. Two different labels (R-Phycoerythrin and Fluorescein isothiocyanate) bound to the monoclonal antibodies are utilized to detect and differentiate the virus targets, i.e. Flu A from “other” and MPV from RSV in the DD kit.

Objective: In this study D³Ultra, D³Duet and D³DD kits were compared for respiratory virus detection on direct specimens.  Direct specimen results were compared to previous direct and culture results using the D³Ultra for the purposes of standard methodology.

Method: 120 previously tested NPS specimens were used in this study. A 5 well slide was dotted with the cell pellet and stained with the D³ Duet RSV (DR) reagent, D³ Duet Influenza A (DIA) reagent, the D³ Double Duet (DD) reagent 1 and reagent 2 and D³ Ultra pool reagent. Slides were examined and evaluated for positivity and staining intensity by a technologist blinded to all previous results.

Results: 109 specimens were positive (73 RSV, 21 Influenza A, 6 MPV, 5 Influenza B, 2 Parainfluenza, 2 Adenovirus) and 11 negative by all staining methods. Two RSV specimens did not stain in all wells. There were no false positives detected.

Conclusions: Performance of all of the kits, were comparable.  Wells contained the same approximate number of positive cells and the staining intensity was similar with no nonspecific staining.