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Chapter 79 : Respiratory Syncytial Virus, Human Metapneumovirus, and the Parainfluenza Viruses
Respiratory syncytial virus (RSV), human metapneumovirus (HMPV), and the parainfluenza viruses (PIVs) are the major viral causes of acute respiratory tract disease in infants and children. A number of major approaches to the laboratory diagnosis of these virus infections are available: (i) tissue culture for virus isolation from respiratory secretions of the upper and lower respiratory tract, (ii) rapid detection of viral antigen in respiratory secretions or middle ear effusions (in otitis media), (iii) viral RNA detection in respiratory secretions, and (iv) determination of specific antibody responses by serological assays. Diagnostic kits based on enzyme linked immunosorbent assay (ELISA) procedures contain all reagents and provide “self-contained” reasonably sensitive and specific assays for routine diagnosis in the hospital laboratory. ELISA, hemagglutination inhibition (HI), immunofluoresence (IF), neutralization (NT), and Western blot (WB) procedures provide highly specific and especially reliable means for the determination of antibody to RSV, HMPV, and PIV. Selection of amplification primers aims at the sequences of the conserved regions of these genes and is based on analyses of these known sequences from several strains of the virus as available in published databases such as GenBank. For the measurement of the level of antibodies to the four PIVs, individual tests must be carried out with the specific virus type as the test virus in the NT test. Since PIVs do not usually produce cytopathic effect (CPE) in cell culture but do exhibit hemadsorption, the end point of the NT procedure is the demonstration of hemadsorption inhibition (HadI).