Immune Response of Tilapia⁢ (Oreochromis niloticus)⁢ after Vaccination with Autoclave-killed, Heat-killed, and Formalin-killed Whole Cell ⁢Aeromonas hydrophila ⁢Vaccines as Possible Serotype-independent Vaccines

Nile tilapia, Oreochomis niloticus, is the most commonly produced and consumed fish in the Philippines. This fish is highly susceptible to Aeromonas hydrophila infection brought about by wastewater contamination. Since antibiotics are not routinely recommended in aqua farming, vaccination is the alternative way in preventing such bacterial infection. This study aimed to evaluate the immune response of Nile tilapia after vaccination with autoclave-killed, heat-killed and formalin-killed whole cells vaccine derived from Aeromonas hydrophila as possible serotype-independent vaccines. One hundred twenty Nile tilapia were randomly distributed into four tanks with corresponding treatments: normal saline solution (NSS), autoclave-killed vaccine (AKV), heat-killed vaccine (HKV), and formalin-killed vaccine (FKV) and were subjected to blood extraction 2 weeks after acclimatization and 2 weeks after vaccination. Immune response was evaluated using agglutination test. On postvaccination, AKV had the highest mean antibody titer (p<0.05). Pre-vaccination antibody level was significantly different to the post-vaccination antibody levels in AKV, HKV, and FKV (p<0.05). This study showed that autoclave-killed, heat-killed, and formalin-killed whole cell Aeromonas hydrophila vaccines are possible serotype-independent whole cell vaccines that produced significant immune response in Nile tilapia. (C) 2018 Friends Science Publishers