Pleurocidin Peptide Enhances Grouper Anti-Vibrio harveyi Immunity Elicited by Poly(lactide-co-glycolide)-Encapsulated Recombinant Glyceraldehyde-3-phosphate Dehydrogenase

Abstract

Outer membrane proteins, such as glyceraldehyde-3-phosphate dehydrogenase (GAPDH), are considered immunodominant antigens for eliciting protective immunity against Vibrio harveyi, the main etiological agent of vibriosis in fish. Cationic antimicrobial peptides (AMPs), such as pleurocidin (PLE), play important roles in activating and recruiting immune cells, thereby contributing to subsequent innate and adaptive immune responses. In the present study, we aimed to use PLE peptide as a potent adjuvant to improve the immunogenicity of V. harveyi recombinant GAPDH (rGAPDH). In order to prepare a controlled-release vaccine, PLE peptide and rGAPDH protein were simultaneously encapsulated into polymeric microparticles made from the biodegradable poly(lactide-co-glycolide) (PLG) polymer. The resulting PLG-encapsulated PLE plus rGAPDH (PLG-PLE/rGAPDH) microparticles, 3.21–6.27 μm in diameter, showed 72%–83% entrapment efficiency and durably released both PLE and rGAPDH for a long 30-day period. Following peritoneal immunization in grouper (Epinephelus coioides), PLG-PLE/rGAPDH microparticles resulted in significantly higher (p < 0.05, nested design) long-lasting GAPDH-specific immunity (serum titers and lymphocyte proliferation) than PLG-encapsulated rGAPDH (PLG-rGAPDH) microparticles. After an experimental challenge of V. harveyi, PLG-PLE/rGAPDH microparticles conferred a high survival rate (85%), which was significantly higher (p < 0.05, chi-square test) than that induced by PLG-rGAPDH microparticles (67%). In conclusion, PLE peptide exhibits an efficacious adjuvant effect to elicit not only improved immunity, but also enhanced protection against V. harveyi in grouper induced by rGAPDH protein encapsulated in PLG microparticles.

Enhanced immune responses and effectiveness of refined outer membrane protein vaccines against Vibrio harveyi in orange‐spotted grouper (Epinephelus coioides)

“…The immunization of fishes with different vaccines induced higher antibody titres and demonstrated a positive correlation with protective efficacy following challenge with V. harveyi (Chuang et al., ; Nguyen, Nguyen, Wang et al., ; Nguyen, Nguyen, Tsai et al., ; Zhang et al., ). In our study, the immunization of groupers with V. harveyi rOMPs vaccines generated high levels of antibodies (IgM) against V. harveyi, with a salient increase observed in the rOmpK‐OmpU treatment group.…”

“…Additionally, Vibrio parahaemolyticus (Li et al., ; Najiah, Lee, Mohd Daud, Mohamed Din, & Mohd Lila, ) and Vibrio alginolyticus (Lee, ; Li et al., ) also infect this fish and have been documented in a number of studies. The application of antibiotics for controlling vibriosis is not in the purview of aquaculture because of serious drawbacks such as drug accumulation in the fish flesh and development of drug resistance in pathogens (Chuang, Huang, Kau, Yang, & Yang, ). Alternatively, vaccination is a safer strategy and has been proven to be an effective means of disease prevention.…”

“…drawbacks such as drug accumulation in the fish flesh and development of drug resistance in pathogens (Chuang, Huang, Kau, Yang, & Yang, 2014). Alternatively, vaccination is a safer strategy and has been proven to be an effective means of disease prevention.…”

Anti-Idiotype Vaccine Provides Protective Immunity Against Vibrio Harveyi in Grouper (Epinephelus Coioides)

“…The virulence of Vh MML-1 and BCRC13812 strains were, respectively, determined to be a highly virulent strain and a lowly virulent strain ( Figure S1). Bacteria were grown in tryptic soy broth (TSB, Difco) with 2% NaCl at 25 • C for 18 h to mid-logarithmic phase [21].…”

“…The bacterial lysate used in the present study was prepared from the highly virulent Vh MML-1 strain of V. harveyi, as described previously [21], with minor modifications. Briefly, V. harveyi (Vh MML-1) was cultured in 50 ml of TSB with 2% NaCl at 25 • C to an OD 600 of 1.…”