Protective Immunity against <i>Vibrio harveyi</i> in Grouper Induced by Single Vaccination with Poly (Lactide-co-glycolide) Microparticles Releasing Pleurocidin Peptide and Recombinant Glyceraldehyde-3-phosphate Dehydrogenase

• Main Authors: Shang-Pin Liu, Shu-Chun Chuang, Chung-Da Yang
• Format: Article
• Language: English
• Published: MDPI AG 2020-01-01
• Series: Vaccines
• Subjects: <i>vibrio harveyi</i> (<i>v. harveyi</i>); single-dose vaccine; pleurocidin (ple); recombinant glyceraldehyde-3-phosphate dehydrogenase (rgapdh); poly(lactide-co-glycolide) (plg); plg-encapsulated ple plus rgapdh microparticles (plg-ple/rgapdh mps)
• Online Access: https://www.mdpi.com/2076-393X/8/1/33

The peptide adjuvant, pleurocidin (PLE), and the <i>Vibrio harvey</i>i antigen, recombinant glyceraldehyde-3-phosphate dehydrogenase (rGAPDH) protein, were encapsulated with poly (lactide-co-glycolide) (PLG) polymers in our previous study to produce PLG-encapsulated PLE plus rGAPDH microparticles (PLG-PLE/rGAPDH MPs) that sustained stable release of both PLE and rGAPDH as well as, after two-time vaccination with MPs, generated long-term protective immunity against <i>V. harveyi</i> in grouper. Stable controlled-release of PLE plus rGAPDH from PLG-PLE/rGAPDH MPs is an attractive feature for developing an effective single-dose vaccine. In the present study, therefore, we aim to evaluate whether single administration with PLG-PLE/rGAPDH MPs in grouper would result in protective immunity against <i>V. harveyi</i>. Peritoneal vaccination of grouper with one dose of PLG-PLE/rGAPDH MPs raised serum titers over a long 12-week period. Moreover, twelve weeks after vaccination, significant lymphocyte proliferation and maximum TNF-&#945; production were found in grouper immunized with a single dose of PLG-PLE/rGAPDH MPs. More importantly, immune responses elicited by single vaccination with PLG-PLE/rGAPDH MPs protected 80% of fish against a lethal peritoneal challenge of the highly virulent <i>V. harveyi</i> (Vh MML-1). In conclusion, our data truly reveal the feasibility of the development of a single-dose vaccine against <i>V. harveyi</i> based on PLG-PLE/rGAPDH MPs.