Abstract: PEG conjugate vaccine of Aeromonas hydrophila was made by the methods of transient high\|temperature, high press and shearing force of ultrasonic, using PEG as ultrasonic medium and vaccine vector. The PEG conjugate vaccine and the traditional vaccine were injected Cryprinuscarpiod intraperitioneally respectively.The percentage of phagocytosis, the index of phagocytosis, antibacterial activity, antibody titer and immune protective efficiency were investigated. The results showed that all the testing indexes of PEG conjugate vaccine were significantly higher than other vaccines. The immune protective efficiency was 80% for PEG conjugate vaccine, which was the highest and 267％ higher than that of traditional vaccine, indicating that PEG6000 was a good binder of vaccine preparation for Cryprinuscarpiod against Aeromonas hydrophila．

Key words: Aeromonas hydrophila, ultrasonic inactivation, PEG conjugate vaccine, immune protective efficiency