[Rapid diagnosis of influenza virus infections from nasopharyngeal secretions].

Since virus isolation consumes a lot of work and time, and virus specific antibodies are not detectable before several days after the onset of illness we developed an enzyme immunoassay (ELISA) for the detection of influenza A and influenza B virus antigen in nasopharyngeal specimens (NPS). This test permits antigen detection within four hours. This ELISA was tested with 119 NPS from children, most of these between 1-12 years old. Virus isolation in MDCK-cells served as control. A total of 67 influenza A/H3N2-, 10 influenza A/H1N1, and 2 influenza B viruses were isolated from cell cultures. 68 (88.3%) of the NPS reacted positive in influenza A virus antigen ELISA, 2 in influenza B virus antigen ELISA, and 9 reacted falsely-negative. The failure to detect antigen could not be solely due to low antigen concentration in the NPS because in 5 materials high concentrations of infectious virus were shown in cell culture. The test allows the rapid diagnosis of influenza virus infections with high efficacy also for laboratories without the facility to perform tissue culture. For accelerating the diagnosis by isolation of viruses in cell cultures, ELISA is useful as cell culture confirmation test, because influenza virus antigen is detectable before a cytopathogenic effect appears.