Similar analytical sensitivity for seasonal influenza virus detection using RPM-Flu and rRT-PCR panel assays.

The Limit of Detection (LoD) for seasonal A/H1N1 and seasonal A/H3N2 influenza viruses are presented as the number of tissue culture (TCID50) or egg culture (EID50) infectious units used for each assay that are demonstrated to result in >95% positive assay outcomes. The relation of tissue culture and egg culture infectious units typically vary with respect to specific influenza virus strain and inoculum. For this table an estimated ratio of 16 EID50 : 1 TCID50 is based upon results of testing the same A/Hawaii/15/2001 (H1N1) strain by both the JBAIDS and CDC rRT-PCR panels.
aThe recently FDA-cleared 510(k)080570 the “CDC Human Influenza Virus Real-time RT-PCR Detection and Characterization Panel” is a test designed to specifically detect contemporary A/H1, A/H3 and A/H5 (Asian Lineage) influenza viruses in humans, as accessed 02 Oct 2009 at http://www.accessdata.fda.gov/cdrh_docs/pdf8/k080570.pdf.
In characterizations of analytical sensitivity of this test panel, the CDC has reported analytical LoD in terms of egg culture infectivity titers (EID50/ml). The Department of Defense Joint Biological Agent Identification & Diagnostic System (JBAIDS) has implemented the same RT-PCR test and reported LoD in TCID50 units of cell culture infectivity, as accessed 02 Oct 2009 at http://www.fda.gov/downloads/MedicalDevices/Safety/EmergencySituations/UCM180067.pdf.
We estimate CDC rRT-PCR LoD results shown in Table 7 using TCID50 units based on the results of both CDC and JBAIDS for A/Hawaii/15/2001(H1N1).