A comparison of commercially available monoclonal antibodies for direct and indirect immunofluorescence culture confirmation and direct detection of parainfluenza viruses.

Two commercially available immunofluorescence monoclonal antibody (MAB) reagents (Bartels, Baxter Healthcare, Issaquah, WA; and Symex, Broken Arrow, OK) were evaluated as a means for detecting parainfluenza virus (PIV) both in shell-vial cultures and directly in clinical specimens. Bartels reagents are used in an indirect immunofluorescence assay (IFA) format and exist as MABs reactive with all three PIV serotypes, individually and in a pool. Symex reagents, also available individually and in a trivalent pool, are used in a direct immunofluorescence assay (DFA) format. Among a total of 299 respiratory specimens, 24 yielded PIV. In a shell-vial culture confirmation test, both the individual and pooled monoclonal antibody reagents from both Bartels and Symex detected all 24 PIV isolates. There were three apparent false-positive results with the Bartels pooled IFA reagents. Of the 299 specimens, 160 were also tested directly for the presence of PIV. There were 13 positive specimens among these 160. The Bartels and Symex monoclonal antibody reagents detected similar percentages of positive samples when used for direct detection (that is, 78.6-85.7). No false-positive results were obtained with any of the reagents in the direct-detection format.