PLGA encapsulated inactivated-viral vaccine: Formulation and evaluation of its protective efficacy against viral haemorrhagic septicaemia virus (VHSV) infection in olive flounder (Paralichthys olivaceus) vaccinated by mucosal delivery routes

• Published in: Vaccine Vol. 37; no. 7; pp. 973 - 983
• Main Authors: Kole, Sajal, Qadiri, Syed Shariq Nazir, Shin, Su-Mi, Kim, Wi-Sik, Lee, Jehee, Jung, Sung-Ju
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 08.02.2019; Elsevier Limited
• Subjects: Antigens; Deoxyribonucleic acid; DNA; Drug delivery systems; Economic impact; Encapsulation; Etiology; Fish; Fish feeds; Fishing; Flounder; Gene expression; Glycolic acid; Hemorrhagic septicemia; Homogenization; Immersion; Immune response; Immune system; Immunity; Immunization; Immunoglobulin M; Infections; Injection; Intestine; Kidneys; Major histocompatibility complex; Marine fish; Mucosal immunity; Mucus; Nanoencapsulation; Nanoparticles; Organs; Paralichthys olivaceus; PLGA; Polylactide-co-glycolide; Skin; Squalene; Submerging; Vaccination; Vaccines; VHSV; Viruses; Water temperature; γ-Interferon; United States > US; PLGA; Mucosal immunity; Nanoencapsulation; VHSV; Paralichthys olivaceus
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2018.12.063

•Encapsulation of inactivated VHSV in PLGA NPs for preparation of PNPs-IV vaccine.•Olive flounder fingerlings immunized with PNPs-IV through immersion and oral routes.•PNPs-IV vaccinated fish exhibited high RPS (60–73.3%) post VHSV challenged.•PNPs-IV immunized group showed higher specific antibody response in sera and mucus.•Immune genes were significantly upregulated in immunized fish. Viral haemorrhagic septicaemia virus (VHSV), an OIE listed viral pathogen, is the etiological agent of a contagious disease, causing huge economic losses in farmed olive flounder (Paralichthys olivaceus) and significant mortalities among several other marine fish species in Korea, Japan, and China. In continuation with our previous work, where injection vaccination with inactivated VHSV mixed with squalene (as adjuvant) conferred higher protective immunity to olive flounder, the present study focused on replacing the injection route of vaccine delivery by immersion/oral route to overcome the limitations of the parenteral immunization method. Here, we encapsulated the inactivated VHSV vaccine with PLGA (poly lactic-co-glycolic acid) nanoparticles (PNPs-IV) and evaluated its ability to induce protective immunity in olive flounder (12.5 ± 1.5 g) by initially immunizing the fishes by immersion route followed by a booster with the same dose two weeks later with half of the fish through immersion route and other half through oral route (incorporated into fish feed). Cumulative mortalities post-challenge (1 × 106 TCID50 virus/fish) with virulent VHSV-isolate, were lower in vaccinated fish and RPS of 60% and 73.3% were obtained for PNPs-IV (immersion/immersion) and PNPs-IV (immersion/oral) groups, respectively. In addition, specific (anti-VHSV) antibody titre in the fish sera, skin mucus and intestinal mucus of the immunized groups were significantly (p < 0.05) enhanced following vaccination. Furthermore, PNPs-IV immunized fish showed significant (p < 0.05) upregulation of different immune gene transcripts (IgM, IgT, pIgR, MHC-I, MHC-II, IFN-γ, and Caspase3) compared to controls, in both the systemic (kidney) and mucosal (skin and intestine) immune compartment of the host post immunization as well as post challenge. Thus it can be inferred that the adopted immunization strategy efficiently protected and transported the inactivated viral antigen to target immune organs and positively stimulated the protective immune response against VHSV in olive flounder.