Evaluation of the efficiency of vaccine against haemorrhagic disease on Tra catfish (Pangasianodon hypophthalmus) from fry to fingerling in laboratory conditions

Abstract

In the aim of developing a vaccine that can be effective against the infection of haemorrhagic disease on fry and fingerling Tra catfish (Pangasianodon hypophthalmus), the virulent Aeromonas hydrophila bacterial strains, isolated from infected Tra catfish in the Mekong Delta, were used to generate numerous Aeromonas hydrophila mutant strains by aroA gene knockout, which prohibits the encoding 5-enolpyruvylshikimate 3-phosphate (EPSP) in shikimate pathway. In the previous research of Biotechnology Center of Ho Chi Minh city, two of these mutant strains (M14 and M25) expressed a large possibility to become the potential attenuated vaccine against hemorrhagic disease on fingerling Tra catfish (possessing Relative Percentage Survival - RPS>70%). In this project, both said mutant strains have been progressed to investigate their single, cross and combined-protective efficiency by immersion method on fry and fingerling Tra catfish in laboratory conditions. The result of this study proved that M14 mutant strain can be used as the dip attenuated vaccine to prevent hemorrhagic disease on fry and fingerling catfish (Relative Percentage Survival – RPS > 75%). Thus, this research plays an important role in making the vaccine applicable in the field. Keywords: Aeromonas hydrophila Haemorrhagic disease Tra catfish aroA gene knockout Attenuated vaccine