Rapid detection of respiratory picornaviruses in nasopharyngeal aspirates by immunofluorescence assay

BACKGROUND: Respiratory picornaviruses (enteroviruses and rhinoviruses) are commonly cited as causes of self-limited upper respiratory tract infection. However, it has recently been suggested that they may cause more severe respiratory disease. Immunofluorescence (IF) assays are rapid and inexpensive and are often used for the detection of respiratory viruses. OBJECTIVES: We sought to develop an IF procedure, using commercially available reagents, for the detection of respiratory picornaviruses directly from nasopharyngeal aspirates (NPA). STUDY DESIGN: From 1st November 2006 until 31st October 2007 all NPA from patients with respiratory infection were stained with the Light Diagnostic Pan-Enterovirus Reagent – “Blend” by IF (IF-ENVPAN). Those specimens which tested positive with this stain were further tested (subject to the availability of frozen specimen) with the xTAG respiratory viral panel, a multiplex PCR directed against respiratory picornaviruses, adenovirus (ADV), respiratory sincytial virus (RSV), influenza viruses A and B (IFA and IFB), parainfluenza virus (PIV) 1–4, human metapneumovirus (HMPV) and coronaviruses. RESULTS: 241/1122 NPA tested positive by IF-ENVPAN. 143 NPA were available for testing by xTAG respiratory viral panel. The multiplex PCR detected respiratory picornaviruses in 139 NPA, in 126 as the sole viral pathogen. CONCLUSIONS: Our results indicate the potential of IF-ENVPAN for the laboratory detection of respiratory picornaviruses in clinical specimens. As far as we are aware, this is the first publication of such a method.