title: Parenteral immunization of PLA/PLGA nanoparticle encapsulating outer membrane protein (Omp) from Aeromonas hydrophila: Evaluation of immunostimulatory action in Labeo rohita (rohu).
abstract: Advanced vaccine research approaches needs to explore on biodegradable nanoparticles (NPs) based vaccine carrier that can serve as antigen delivery systems as well as immuno-stimulatory action to induce both innate and adaptive immune response in fish. Immunogenicity of PLA and PLGA NPs encapsulating outer membrane protein (Omp) antigen of Aeromonas hydrophila were evaluated through intra-peritoneal injection in fish, Labeo rohita. Antigen loaded PLA-Omp (223.5 ± 13.19 nm) and PLGA-Omp (166.4 ± 21.23 nm) NPs were prepared using double emulsion method by efficiently encapsulating the antigen reaching the encapsulation efficiency 44 ± 4.58% and 59.33 ± 5.13% respectively. Our formulated PLA Omp and PLGA-Omp NPs were in nanometer range (<500 nm) and could be successfully endocyted in the body. Despite low antigen loading in PLA-Omp, it showed considerably slower antigen release in vitro than PLGA-Omp NPs. Other physical properties like zetapotential values and poly dispersity index (PDI) confirmed the stability as well as monodisperse nature of the formulated nanoparticles. The spherical and isolated nature of PLA-Omp and PLGA-Omp NPs were revealed by SEM analysis. Upon immunization of all antigenic formulations (PLA-Omp NP, PLGA-Omp NP, FIA-Omp, PLA NP, PLGA NP, PBS as control), significant higher bacterial agglutination titre and haemolytic activity were observed in case of PLA-Omp and PLGA-Omp immunized groups than rest groups at both 21 days and 42 days. The specific antibody response was significantly increased and persisted up to 42 days of post immunization by PLA-Omp, PLGA-Omp, FIA-Omp. PLA-Omp NPs showed better immune response (higher bacterial agglutination titre, haemolytic activity, specific antibody titre, higher percent survival upon A. hydrophila challenge) than PLGA-Omp in L. rohita confirming its better efficacy. Comparable antibody response of PLA-Omp and PLGA-Omp with FIA-Omp treated groups suggested that PLA and PLGA could be replacement for Freund's adjuvant (for stimulating antibody response) to overcome many side effects offering long lasting immunity. Our encouraging results suggest that PLA/PLGA nanoparticles based delivery system could be a novel antigen carrier for parenteral immunization in fish.
authors.affiliation: Immunology and Molecular Medicine Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Odisha 769008, India.
authors.forename: Pradipta Ranjan
authors.initials: PR
authors.lastname: Rauta
authors.affiliation: Immunology and Molecular Medicine Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Odisha 769008, India. Electronic address: nayakb@nitrkl.ac.in.
authors.forename: Bismita
authors.initials: B
authors.lastname: Nayak
mesh_terms: D016980:Aeromonas hydrophila; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000942:Antigens, Bacterial / Q000008:administration & dosage* / Q000276:immunology; D001425:Bacterial Outer Membrane Proteins / Q000008:administration & dosage* / Q000276:immunology; D003530:Cyprinidae / Q000097:blood / Q000276:immunology*; D005393:Fish Diseases / Q000276:immunology; D016905:Gram-Negative Bacterial Infections / Q000276:immunology / Q000662:veterinary*; D007114:Immunization; D019344:Lactic Acid / Q000008:administration & dosage*; D008855:Microscopy, Electron, Scanning; D053758:Nanoparticles / Q000008:administration & dosage* / Q000648:ultrastructure; D011100:Polyglycolic Acid / Q000008:administration & dosage*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid
keywords: Fish Immune response; Nanoparticles; Omp; PLA; PLGA