New York, May 23 (IANS): The US researchers have developed vaccines that can protect chickens from two new strains of avian influenza that can be transmitted from poultry to humans.

"We focused on avian influenza virus subtype H5N1, which can get transmitted from chickens to humans (zoonotic strain)," explained one of the researchers Juergen A Richt, professor of veterinary medicine at the Kansas State University.

"So far it has infected more than 700 people worldwide and has killed about 60 percent of them. Unfortunately, it has a high mortality rate," he pointed out.

The researchers developed the vaccine for H5N1 by combining two viruses.

A vaccine strain of the Newcastle disease virus, a virus that naturally affects poultry, was cloned and a small section of the H5N1 virus was transplanted into the Newcastle disease virus vaccine, creating a recombinant virus.

Tests showed that the new recombinant virus protected chickens against both Newcastle disease virus and H5N1.

Researchers also examined the avian flu subtype H7N9, an emerging zoonotic strain.

Using the same method for developing the H5N1 vaccine, the researchers inserted a small section of the H7N9 virus into the Newcastle disease virus vaccine. Chickens given this recombinant vaccine were protected against the Newcastle disease virus and H7N9.

"We believe this Newcastle disease virus concept works well for poultry," Richt said.

The new vaccine development method may help researchers make vaccines for avian influenza more quickly.

It also may lead to new influenza vaccines for pigs, sheeps and other livestock, Richt said.

The results appeared in the Journal of Virology.