Efficacy of Feed-Based Formalin-Killed Vaccine of Streptococcus iniae Stimulates the Gut-Associated Lymphoid Tissues and Immune Response of Red Hybrid Tilapia

Abstract

Red hybrid tilapia were fed a formalin-killed oral Streptococcus iniae vaccine (FKV) in the present study was assessed. Three hundred Red hybrid tilapia 80 ± 10 g were divided into five groups (1A, 1B, 2A, 2B, and Cx), each consisting of 60 fish. Fish from Groups 1A, 1B, 2A, and 2B were fed with FKV over different periods of administration, while Group 2B was the only group of fish to receive an oral booster vaccination on day 14- and 21-days post-vaccination (dpv). Group Cx was fed with normal pellets containing no vaccine as a control group. At four weeks post-vaccination (wpv), all fish were experimentally infected with S. iniae. Groups 2A and 2B had the lowest level of mortalities following vaccination (45% and 30%, respectively) compared to Groups 1A and 1B (80% and 55%, respectively), while the level of mortalities in Group Cx was 100%. All vaccinated groups showed a significant increase in anti-S. iniae IgM levels (p < 0.05) in serum, mucus, and gut-lavage, while Group Cx did not (p > 0.05) and all fish in this group died by five weeks post-infection. In conclusion, fish fed with the S. iniae FKV had a greater level of protection against S. iniae, with increased specific antibody response to the vaccine and there was also evidence of GALT stimulation by the vaccine.

A Novel Efficient Piscine Oral Nano-Vaccine Delivery System: Modified Halloysite Nanotubes (HNTs) Preventing Streptococcosis Disease in Tilapia (Oreochromis sp.)

“…Once the HCF passes from the stomach to the intestine, hydrolysis promptly takes place, leading to a significant shift from the protein to short soluble polypeptides or oligo- and dipeptides [ 56 ]. Afterwards, those peptides are absorbed as a result of activating specific immunity through gut-associated lymphoid tissue (GALT) immunity [ 59 ]. This observation confirmed the achievement in inducing immunity in orally vaccinated fish, and HC and HCF were suggested to be potent delivery agents for oral vaccination in fish.…”

Novel efficiently piscine orally nano-vaccine delivery system: modified halloysite nanotubes (HNTs) preventing streptococcosis disease in Tilapia (Oreochromis sp.)

“…Once the HCF passes from the stomach to the intestine, hydrolysis is promptly taken place, leading to a signi cant shift from protein to short soluble polypeptides or oligo-and dipeptides [56]. Thus, those peptides were uptake and latter activation speci c immunity through Gut-associated lymphoid tissue (GALT) immunity [59]. This observation con rmed the achievement in inducing immunity in orally vaccinated sh and HC and HCF were suggested to be a potent delivery agent for orally vaccination in sh.…”

Current status and advances of fish vaccines in Malaysia

“…Hence, it is now realized that these bacteria pose a considerable threat to tilapia farming, so producing an effective vaccine is rather urgent. In Malaysia, several types of vaccines, such as inactivated, recombinant, and live attenuated vaccines; Different routes of vaccination, such as oral, injectable, or immersion, were extensively explored by local researchers against S. agalactiae and S. iniae (Table -4) [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59].…”

“…A low number of antigens at 72 h post-challenge in the group receiving the routine oral vaccine (5 consecutive days and booster on days 14 and 21) displayed the simulation and irregular projection of M-cells with variable morphology and antigen distribution pattern. Further, they reported that fish immunized with biofilm vaccine had significantly higher antibody levels in their serum, mucus, and gut lavage (p<0.05) than fish immunized with the whole-cell vaccine or the control group [51]. Moreover, they discussed evidence indicating a high level of GALT stimulation in the lamina propria in the form of lymphoid cell aggregations.…”