We have compared the novel ResPlex III assay and
existing techniques for the detection and subtyping of influenza virus during the influenza season 2006–2007 CB-839 . The methodology must necessarily make some compromises, for example, with regard to amplification conditions during the first cycles with specific primers. Thus it is not expected that sensitivity will be the same as that of monoplex PCRs. When compared to an in-house quantitative real-time PCR for influenza virus (detection limit 1–10 TCID50/ml of a fresh influenza virus harvest), the ResPlexII v2.0 test appeared to be about 1 log10 step less sensitive. The majority of positive results obtained with the ResPlexII v2.0 test could be confirmed by other, independent conventional published, in-house qRT-PCRs or commercially available PCR methods which used other target regions of the viral genomes. This applies to all 317 influenza positive samples, 10 of 10 RSV A and B positive samples tested, 6 of 6 adenovirus positive samples, 3 of 3 bocavirus positive samples (including one questionable ResPlex result), and 13 of 14 positive coronavirus
samples (including 2 questionable ResPlex results). Differences were found for 2 parainfluenza virus 3 samples, for which ResPlex results could not be confirmed; likewise only 11 of 16 rhinovirus samples and 9 of 22 enterovirus samples tested negative in independent PCRs, but were positive with www.selleckchem.com/products/AZD2281(Olaparib).html the ResPlex method. It remains to be determined whether the observed discrepancies are weaknesses of the ResPlex system or of the other, independent PCRs. However, the manufacturer of the ResPlex method confirmed certain cross-reactivities between enteroviruses and rhinoviruses, which have conserved 5′ UTR regions that were used as
targets for the PCR primers. Since it is known that reovirus may grow in MDCK cells , we also screened many samples with an in-house reovirus qRT-PCR specific for mammalian orthoreovirus 1-3 (conserved region of the L3 inner capsid gene). Samples in which no other virus was detected by the ResPlex method were preferably used for the reovirus PCR. No reovirus Levetiracetam was found in 271 of the specimens for which sufficient material was still available. Whereas the specific virus growth studies summarized and discussed further above applied cell-culture adapted virus strains, the studies reported here used unadapted field virus strains and technical conditions as applied for influenza virus isolation and passaging. These studies confirmed that isolating influenza viruses in MDCK 33016PF cells effectively reduced co-infecting viruses. After only two passages and a 10−7 to 10−9 total dilution of the original specimen, adeno-, boca-, corona-, entero-, and rhinoviruses were no longer detectable. Only influenza viruses were recovered and remained the only detectable virus upon further passage.