1.2. Antigen capture and molecular techniques
At present, the conventional virus isolation and characterisation techniques for the diagnosis of
influenza A remain the methods of choice, for at least the initial diagnosis of influenza A infections.
However, conventional methods tend to be costly, labour intensive and slow. There have been
enormous developments and improvements in molecular and other diagnostic techniques, many of
which have been applied to the diagnosis of influenza A infections.
1.2.1. Antigen detection
There are several commercially available AC-ELISA kits that can detect the presence of
influenza A viruses in poultry (Swayne et al., 2013; Woolcock & Cardona, 2005). Most of the kits
are enzyme immunoassays or are based on immunochromatography (lateral flow devices) and
use a monoclonal antibody against the nucleoprotein; they should be able to detect any
influenza A virus. The main advantage of these tests is that they can demonstrate the presence
of influenza A within 15 minutes. The disadvantages are that they may lack sensitivity, they may
not have been validated for different species of birds, subtype identification is not achieved and
the kits are expensive. The tests should only be interpreted on a flock basis and not as an
individual bird test. Oropharyngeal or tracheal samples from clinically affected or dead birds