A proof-of-principle study from Peking University in China provides a simpler method for developing efficacious vaccines. In the method, live viruses are genetically manipulated to activate the immune system without harming healthy cells. The vaccine produced by this method effectively protects experimental animals from influenza viruses.
The study, led by Prof Demin Zhou, has been outlined in the respected journal Science. Prof Zhou hope that their method can also be used to create vaccines to other viruses.
Live attenuated vaccines are generally very potent -- they elicit strong cellular and antibody responses. But the living microbes that have been weakened still have the potential to revert to their virulent form and cause disease, which limits their use. If a method can lower their toxicity to make them safe and maintain their ability to trigger strong immune response, it will revolutionize the development of vaccine.
In the work, first author Longlong Si changed the genome of influenza A viruses to make them unable to replicate in conventional cells but able to activate the immune system. They tested the modified viruses in animals including mice, guinea pigs, and ferrets. When the animals received one dose of the modified viruses, it triggered an antibody response. A second dose greatly increased the production of antibodies in the animals. Such viruses also provided protection against other strains of influenza.