A protocol has been developed for genetically engineering an attenuated pathogen such as the influenza virus that can grow in cells without interferons but has suppressed growth in cells with the interferons. The protocol comprises systematically identifying immune evasion functions on the pathogen's genome, then eliminating the immune evasion functions while maintaining a certain replication fitness of the pathogen. The resulting attenuated pathogen causes a strong immunologic response and can be used in a live attenuated vaccine.
