Xinhua News Agency, Hangzhou, October 26 (Reporter Zhang Yue) Chinese Scientists announced the successful development of H7N9 avian influenza virus vaccine strains on Oct. 26 in Hangzhou.

Currently, the vaccine seed strains have passed the safety evaluation experiments of Chinese Academy of Medical Sciences Institute of Laboratory Animal Research Center for Drug Safety Evaluation. Referring to the technical requirements of influenza virus vaccine strain in “Chinese Pharmacopoeia”, Chinese Academy of Food and Drug Testing also has a test of the seed strains.

The results showed that the vaccine strain was significantly decreased in pathogenicity than the wild-type H7N9 strain, and was approximate to the standard highly attenuated strain of influenza virus – PR8. Its base indicators were in line with the requirements of influenza virus vaccine strain. This indicates that the virus strain has been ready for the influenza virus vaccine manufacturers to produce and can be declared for production.

As one of the National Major Infectious Diseases Prevention Projects, the project was collaboratively completed by Zhejiang University the First Affiliated Hospital with Hong Kong University, China Disease Prevention and Control Center, Chinese Academy of Food and Drug Testing, Chinese Academy of Medical Sciences and other units.

Li Lanjuan, the project leader and academician of Chinese Academy of Engineering, introduced that, the research team received the throat swab samples of H7N9 cases on April 3 and successfully isolated a strain of H7N9 avian influenza virus. Subsequently, the research team applied the internationally accepted method for preparing influenza vaccine seed strains, they used the reverse genetics technology on PR8 plasmid as virus backbone for gene rearrangement with self-isolated virus strains, and successfully developed the H7N9 influenza vaccine seed strains.

To ensure the safety of the vaccine seed strains, researchers planted the seed strains in specific pathogen-free chick embryo for continuous passage of 15 generations and confirmed the genetic stability.

In March this year, China first reported a newly discovered avian influenza virus H7N9. The virus can be transmitted to humans through poultry, causing severe pneumonia and was life-threatening. As of Oct. 24, China has totally reported 136 cases of H7N9 avian influenza virus infection, of which 45 were fatal. The fatality rate is of 33.1%. Researchers also found that, H7N9 was able to cross species and likely to infect between human.

In the past, the influenza vaccine strains required for productions of vaccine in China were provided by World Health Organization, due to the fact that China was lack of the developing technology of influenza vaccine strains. “The successful development of H7N9 virus vaccine strain has provided powerful technical support for coping with new influenza epidemic and contributed to the global control of H7N9 avian influenza epidemic.” Director of World Health Organization Collaboration Center and Chinese National Influenza Center, Shu Yuelong said.