[Purification and identification of avian influenza viruses causing mixed multi-infection]

To purify and identify avian influenza viruses causing multi-subtype mixed infection.

By using chicken embryo end-point dilution or combining with specific antiserum neutralizing tests, the mix-infection samples of 2 or 3 subtyping avian influenza viruses were purified, and the results of purification were identified by RT-PCR and hemagglutination inhibition tests. These methods were used to purify and identify 214 positive samples of avian influenza viruses.

The method of chicken embryo end-point dilution was able to purify the viruses from samples by dilution and subculturing six or seven passages. However, combining this method with the specific antiserum neutralizing tests, the samples could be purified after four or five passages. The accuracy of identification could be obviously enhanced by using RT-PCR and hemagglutination inhibition tests simultaneously. Based on these methods, 233 of avian influenza viruses, which constituted 13 subtypes, were purified from 214 samples.

Both chicken embryo end-point dilution method and its combination with specific antiserum neutralizing tests could be used to purify avian influenza viruses of mix-infection, however, the latter may be more focused and valid. In addition, the results of purification should also be evaluated by multiple means.