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<OL> <LI> Determine the ability of current vaccine seed strains and vaccines to protect chickens against emerging H5N1 high pathogenicity avian influenza field viruses. <LI> Develop new vaccine seed strains against the H5N1 HPAI antigenic variants in Egypt.
APPROACH: Commercial avian influenza (AI) vaccines, vaccine seed strains and field H5N1 high pathogenicity (HP) AI viruses will be obtained from Egypt. Viruses will be analyzed by sequencing and antigenic profiling and Egyptian scientists will be training in the research methods. Vaccines will be evaluated in a chicken model for potency using serological tests samples from vaccinated birds and efficacy by challenge with antigenic drift field viruses and measuring protection by prevention of morbidity, mortality and replication of challenge virus. Typing antisera will be produced in chickens and used in in vitro serological tests to assess antigenic variants of additional field viruses. Using the accumulated data, replacement vaccine strains will be developed.