The School of Public Health at The University of Hong Kong's Li Ka Shing Faculty of Medicine published its research findings yesterday in the international academic journal "Proceedings of the National Academy of Sciences." The research team, in collaboration with scholars from the National Cancer Institute of the U.S. National Institutes of Health, successfully modified the existing smallpox vaccine into a "new influenza A vaccine." Experiments on mice revealed that the mice were able to resist various types of influenza A, including the H7N9 avian influenza currently rampant in mainland China, H5N1 avian influenza, human seasonal influenza H3N2 and H1N1, and the highly pathogenic H7N7.
Smallpox Vaccine Mixed with Influenza Genes to Boost Immunity
The research began in 2009. The new vaccine uses the "attenuated vaccinia virus" from the smallpox vaccine as a carrier, incorporates genes from five H5N1 avian influenza viruses, and is injected with human cytokine IL-15, which can enhance immune responses, causing the vaccinia virus to become an avian influenza virus antigen protein.
Leo Poon Lit-man, Associate Professor at the School of Public Health who led the research, stated that previous development of influenza A vaccines relied heavily on whether they could produce viral antibodies. However, the new vaccine can stimulate T-lymphocytes that recognize influenza A viruses, thereby generating immunity, which helps reduce fatal conditions, shorten the duration of illness, and provide better protection.
Immunity Within 7 Days of Vaccination, Protecting Against H5N1 and H7N9
Poon noted that in mouse experiments, the mice developed immunity 7 days after receiving the new vaccine. Researchers then injected the mice with high doses of influenza virus for testing. The results showed that the survival rate of mice injected with H5N1, H7N9, H3N2, and H1N1 reached 100%, while the survival rate of mice injected with the H7N7 virus was 80%. In contrast, all mice in the control group that did not receive the new vaccine had a 100% mortality rate.
Poon said that since humans do not know what kind of influenza will prevail in the future, and existing seasonal influenza vaccines cannot prevent new avian influenza, such as H5 and H7 viruses, there is an urgent need to develop a broad-spectrum influenza A vaccine that can enhance various immune system elements and provide cross-subtype protection. "The attenuated vaccinia virus has been used to manufacture human smallpox vaccines, with over 1 billion doses used to date. Therefore, when the demand for vaccination surges due to an influenza pandemic, the new vaccine can be mass-produced using existing production facilities."
Next Step: Testing on Monkeys and Ferrets
Poon stated that it remains to be studied how many groups the new vaccine can actually handle. The research team will conduct tests on other animal models, including monkeys and ferrets, before human clinical trials can begin. There is currently no set timeline for the release of the new vaccine.
