Avian Influenza Virus Isolation, Propagation, and Titration in Embryonated Chicken Eggs

Avian influenza virus and some mammalian influenza A viruses can be isolated, propagated, and titrated in embryonated chicken eggs (ECEs). Most sample types can be accommodated in ECE culture with appropriate processing. Isolation may also be accomplished in cell culture, and if a mammalian lineage influenza A is expected to be in an avian sample, for example swine influenza in turkey specimens, mammalian cell may be preferable. Culture in ECEs is highly sensitive but is not specific for influenza A, which may be an advantage because a sample may be screened for several agents at once. Once an agent is isolated in culture, the presence of influenza viruses can be confirmed by hemagglutination inhibition assay, antigen immunoassay, agar gel immunodiffusion assay, or RT-PCR. Finally, ECEs may be used to propagate and titrate an avian influenza virus.