Genetically engineered from a weakened bird virus called Newcastle disease virus (NDV), the new vaccine can protect against not only the highly pathogenic H5 avian influenza, but also the Newcastle disease, said the researchers from German Federal Institute for Animal Health and the Internet company based in the United States.

Their report was published in the May 22 issue of the Proceedings of the National Academy of Sciences.

Newcastle disease, an economically important viral disease of poultry, is currently controlled by routine vaccination. The researchers said they produced this combo vaccine by inserting a bird flu gene into the NDV genome.

Through genetic engineering, the researchers led by Angela Roemer-Oberdoerfer inserted the hem-agglutinin gene H5 of the highly pathogenic avian influenza strain H5N2 into the NDV viral genome.

Thus, they actually produced a new virus called NDVH5m.

The resulting recombinant virus induced antibody production against both NDV and avian influenza and protected chickens against these diseases after exposure to lethal doses of both viruses, the researchers said.

"Immunization of chickens with NDVH5m induced NDV and Avian Influenza Virus (AIV) H5-specific antibodies, and protected chickens against clinical disease after challenge with a lethal dose of velogenic NDV or highly pathogenic AIV, respectively," they wrote in the paper.

The new study demonstrates the possibility of designing affordable and effective vaccines against multiple poultry diseases, they added.

These dual vaccine strategies may also provide methods for controlling the growing public health threat of avian flu.

"Recombinant NDVH5m is suitable as a bivalent vaccine against NDV and AIV and may be used as marker vaccine for the control of avian influenza," the researchers said.