Detection of respiratory syncytial virus antigens in cells from nasopharyngeal secretions. Indirect immunofluorescence [M. Battaglia, L. Balducci. 1980 - Rapid diagnosis of respiratory syncytial virus infections by immunofluorescence on cell smears from nasopharyngeal secretions. Bollettino dell'Istituto Sieroterapico Milanese 59:121-125].