Comparison of two multiplex methods for detection of respiratory viruses: FilmArray RP and xTAG RVP

Abstract

We compared the FilmArray RP (Idaho Technology, Inc., Salt Lake City, UT) and the xTAG RVP (Luminex Corporation, Toronto, Canada) multiplex respiratory virus PCR methods for the detection of respiratory viruses in a set of 200 patient specimens frozen at -70 °C after standard viral culture and antigen detection methods were done. Both systems detected between 40 to 50% more viruses than traditional methods, primarily rhinoviruses and human metapneumovirus. The FilmArray RP detected significantly more total viruses either alone or as part of mixed infections than the xTAG RVP, as well as an additional 21.6% more respiratory syncytial viruses. The xTAG RVP requires 5 to 6 h with 2.5 to 3 h of hands-on time, while the FilmArray RP takes about an hour with 3 to 5 min of hands-on time, making it much easier to perform.

Fig. 1.

The dried reagents in the FilmArray RP pouch are reconstituted by the addition of 1 ml distilled water to the blue port (lower right of diagram), and the diluted sample is injected into the port shown in red. The pouch is then bar code read and placed in the FilmArray RP instrument (upper right). The steps inside the instrument are shown on the left: cell lysis, nucleic acid extraction, and washing, followed by multiplex RT-PCR I and then the specific-virus nested PCRs in PCR II.

Fig. 2.

Relationship between the C_T of the FilmArray RP and the MFI of the xTAG RVP. In the xTAG RVP, an MFI of ≥300 is considered positive and 150 to 299 is considered equivocal. For graphic purposes, specimens positive for RSV by the FilmArray RP but negative by the xTAG RVP are shown as having an xTAG RVP MFI of 100, below the positive range. There were 8 such specimens, but due to the closeness of some of the C_Ts, all 8 do not show up as individual points.