Vaccines developed for H5N1, H7N9 avian influenza strains

Researchers have used a new method to develop vaccines for two strains of avian influenza that can be transmitted from poultry to humans. The strains have led to the culling of millions of commercial chickens and turkeys as well as the death of hundreds of people.

The new vaccine development method is expected to help researchers make vaccines for emerging strains of avian influenza more quickly, said Jürgen Richt, Regents distinguished professor of veterinary medicine at Kansas State University and director of the US Department of Homeland Security's Center of Excellence for Emerging and Zoonotic Animal Diseases.

Richt and his colleagues focused on the avian influenza virus subtype H5N1, a new strain most active in Indonesia, Egypt and other Southeast Asian and North African countries, as well as subtype H7N9, an emerging zoonotic strain that has been circulating in China since 2013.

H5N1 has infected more than 700 people worldwide with a mortality rate of approximately 60%. About 230 people have died from H7N9, from around 650 reported cases.

The researchers created vaccines for H5N1 and H7N9 by combining each virus with the vaccine for the Newcastle disease virus, which occurs naturally in poultry.

Tests showed that the two new recombinant viruses vaccinated chickens against both Newcastle disease virus and H5N1/H7N9.

"We believe this Newcastle disease virus concept works very well for poultry because you kill two birds with one stone, metaphorically speaking," Richt said. "You use only one vector to vaccinate and protect against a selected virus strain of avian influenza."

Using the Newcastle disease virus for vaccine development may extend beyond poultry to pigs, cattle and sheep, Richt said. Researchers found they were able to protect pigs against an H3 influenza strain by using the Newcastle disease virus to develop a recombinant virus vaccine. Wenjun Ma, Kansas State University assistant professor of diagnostic medicine and pathobiology, is building on this finding and using the Newcastle disease virus to make a vaccine for porcine epidemic diarrhoea virus, a disease that has killed an estimated 6 million pigs.

Findings from the avian influenza study have been published in the Journal of Virology.

Image caption: Wenjun Ma, left, and Jürgen Richt have developed vaccines for H5N1 and H7N9, two emerging strains of avian influenza.