New test picks out native from mutant H5N1 strains

A University of Adelaide-led project has developed a new test that can distinguish between birds that have been vaccinated against the H5N1 strain of avian influenza virus with those that have been naturally infected.

This is a significant step in the fight against this often fatal strain of avian influenza which is widespread in the poultry populations of Southeast Asia, particularly Indonesia and Vietnam.

"The inability of distinguishing between vaccinated and naturally infected birds has been a major challenge. It has prevented tracking the virus which can still circulate in vaccinated birds and may mutate to new strains under what's called vaccination pressure," said Dr. Farhid Hemmatzadeh, senior lecturer in Virology in the School of Animal and Veterinary Sciences at the Roseworthy campus.

"These birds that have been vaccinated but still have live naturally infected H5N1 virus in their systems are the main source of emerging strains of the virus - and these new strains may be even more dangerous to birds or humans. With this new, more sensitive test we can identify these vaccinated birds with live virus and prevent the escape of any mutant strains."

The researchers, including the University of Melbourne, CSIRO and Indonesian organisations, are carrying out large surveillance programmes in poultry farms across Indonesia. The research is funded by the Australian Centre for International Agricultural Research (ACIAR).

The new DIVA (differentiation of infected from vaccinated animals) test uses a particular viral protein called Matrix protein 2 that reacts differently with blood serum from vaccinated or infected animals. Since the first outbreak of H5N1 in 2004, the development of a reliable DIVA test has been a global priority.