Feed-based biofilm vaccine for the evaluation of immune response and disease resistance of striped catfish, Pangasianodon hypophthalmus (Sauvage ۱۸۷۸) against Aeromonas hydrophila infection

Striped catfish, Pangasianodon hypophthalmus was immunized with Biofilm (BF) and Free cell (FC) of Aeromonas hydrophila vaccine at ۱۰۱۰ CFU g-۱ for ۲۰ days and monitored for growth parameters, immune responses and disease resistance up to ۶۰-day post vaccination (dpv). Pangasius catfish in the BF vaccinated group had considerably higher (p<۰.۰۵) growth and feed utilization than the FC vaccinated and control groups. The vaccinated fishes were challenged with A. hydrophila at ۱۰۷ CFU/ml. A very high relative percentage survival was recorded with BF (۸۴.۲۱%) compared to that with FC (۳۳.۳۳%). Polyclonal antibody-based ELISA was used to quantify the antibody titre. BF vaccinated group showed significantly higher antibody titer compared to other treatments. Moreover, higher haematological parameters recorded in the present study, were differentially invigorated by the oral administration of A. hydrophila biofilm vaccine. Furthermore, biochemical stress parameters (SGPT, SGOT etc.) in the vaccination groups showed an incremental trend in the early timeline. However, the values in the biofilm group displayed down regulated on ۲۰ dpv onwards indicating improved health condition. Vaccinated BF fishes showed gut associated lymphoid tissues (GALT) within the laminar propria of mid gut. But in FC group fishes showed less aggregation of lymphoid cells. The unvaccinated control fish had no lymphoid cell aggregation in their intestines. The findings of the current research suggested that biofilm vaccine has the capability to be one of the potential oral vaccines in striped catfish against A. hydrophila infection.

Keywords:

Biofilm oral vaccine , Aeromonas hydrophila , Growth performance , haematology , Biochemical parameters , Pangasianodon hypophthalmus