K-STATE (KSNT) – A Kansas State University researcher has helped detail development of a vaccine for two new strains of avian influenza—strains that can be transmitted from poultry to people. Chicken and turkey farms have been forced to cull millions of commercial birds and hundreds of people have died in the countries where it’s most active: Indonesia, Egypt and other Southeast Asian and North African countries..
The new method of vaccine development was discovered by Wenjun Ma, assistant professor of diagnostic medicine and pathobiology at Kansas State University and research partner Jürgen Richt, Regents distinguished professor of veterinary medicine and director of the U.S. Department of Homeland Security’s Center of Excellence for Emerging and Zoonotic Animal Diseases. The pair has now developed vaccines for avian influenza strains H5N1 and H7N9, which can be transmitted from birds to pigs to humans. H5N1 has been detected in wild birds in the U.S. although the numbers are much lower than in the countries mentioned above.
Researchers anticipate that the new method will allow them to make vaccines for new strains of avian influenza faster. That means that the number and intensity of large-scale outbreaks can be reduced at poultry farms. It will also lessen and possibly prevent human transmission. Another positive development is that the discovery could lead to new influenza vaccines for pigs and vaccines for other livestock as well according to Richt.
“So far it [H5N1] has infected more than 700 people worldwide and has killed about 60 percent of them. Unfortunately, it has a pretty high mortality rate,” Richt explained.
Two viruses were combined to develop the H5N1 vaccine. According to Richt, 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 virus made up of re-combined DNA. Tests showed that the new virus protected chickens against both Newcastle disease virus and H5N1.
Researchers also looked at the avian flu subtype H7N9, an emerging strain that has been circulating in China since 2013. It, too, can be transmitted to humans. China has reported about 650 cases in humans and Canada has reported two cases in people returning from China. That strain has caused about 230 deaths—1 in 3 infected people die.
“In Southeast Asia there are a lot of markets that sell live birds that people can buy and prepare at home,” Richt said. “In contrast to the H5N1 virus that kills the majority of chickens in three to five days, chickens infected with the H7N9 virus do not show clinical signs of sickness. That means you could buy a bird that looks perfectly healthy but could be infected. If an infected bird is prepared for consumption, there is a high chance you could get sick.”
Researchers used the same method for the H5N1 vaccine to develop one for the H7N9 strain.
The process is promised for other farm animals. 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. Now, Wenjun Ma, the K-State researcher, is taking this finding to the next level to develop a vaccine for porcine epidemic diarrhea virus. That disease that has killed an estimated 6 million pigs.
Richt conducted the avian influenza study with Ma, Adolfo Garcia-Sastre at the Icahn School of Medicine at Mount Sinai in New York, and several other colleagues. They published their findings in the Journal of Virology study,“Newcastle disease virus-vectored H7 and H5 live vaccines protect chickens from challenge with H7N9 or H5N1 avian influenza viruses.”