Edwardsiella tarda OmpA Encapsulated in Chitosan Nanoparticles Shows Superior Protection over Inactivated Whole Cell Vaccine in Orally Vaccinated Fringed-Lipped Peninsula Carp (Labeo fimbriatus)
Saurabh Dubey,
Kiran Avadhani,
Srinivas Mutalik,
Sangeetha Madambithara Sivadasan,
Biswajit Maiti,
Shivani Kallappa Girisha,
Moleyur Nagarajappa Venugopal,
Stephen Mutoloki,
Øystein Evensen,
Indrani Karunasagar,
Hetron Mweemba Munang′andu
Affiliations
Saurabh Dubey
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India
Kiran Avadhani
Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, India
Srinivas Mutalik
Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, India
Sangeetha Madambithara Sivadasan
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India
Biswajit Maiti
UNESCO MIRCEN for Marine Biotechnology, Nitte University Centre for Science Education and Research, Paneer Campus, Deralakatte, Mangalore 575018, India
Shivani Kallappa Girisha
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India
Moleyur Nagarajappa Venugopal
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India
Stephen Mutoloki
Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Department of Basic Sciences and Aquatic Medicine, Section of Aquatic Medicine and Nutrition, Adamstuen Campus, Ullevålseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway
Øystein Evensen
Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Department of Basic Sciences and Aquatic Medicine, Section of Aquatic Medicine and Nutrition, Adamstuen Campus, Ullevålseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway
Indrani Karunasagar
UNESCO MIRCEN for Marine Biotechnology, Nitte University Centre for Science Education and Research, Paneer Campus, Deralakatte, Mangalore 575018, India
Hetron Mweemba Munang′andu
Norwegian University of Life Sciences, Faculty of Veterinary Medicine, Department of Basic Sciences and Aquatic Medicine, Section of Aquatic Medicine and Nutrition, Adamstuen Campus, Ullevålseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway
The use of oral vaccination in finfish has lagged behind injectable vaccines for a long time as oral vaccines fall short of injection vaccines in conferring protective immunity. Biodegradable polymeric nanoparticles (NPs) have shown potential to serve as antigen delivery systems for oral vaccines. In this study the recombinant outer membrane protein A (rOmpA) of Edwardsiella tarda was encapsulated in chitosan NPs (NP-rOmpA) and used for oral vaccination of Labeo fimbriatus. The rOmpA purity was 85%, nanodiameter <500 nm, encapsulation efficiency 60.6%, zeta potential +19.05 mV, and there was an in vitro release of 49% of encapsulated antigen within 48 h post incubation in phosphate-buffered saline. Empty NPs and a non-formulated, inactivated whole cell E. tarda (IWC-ET) vaccine were used as controls. Post-vaccination antibody levels were significantly (p = 0.0458) higher in the NP-rOmpA vaccinated fish (Mean OD450 = 2.430) than in fish vaccinated with inactivated whole cell E. tarda (IWC-ET) vaccine (Mean OD450 = 1.735), which corresponded with post-challenge survival proportions (PCSP) of 73.3% and 48.28% for the NP-rOmpA and IWC-ET groups, respectively. Serum samples from NP-rOmpA-vaccinated fish had a higher inhibition rate for E. tarda growth on tryptic soy agar (TSA) than the IWC-ET group. There was no significant difference (p = 0.989) in PCSPs between fish vaccinated with empty NPs and the unvaccinated control fish, while serum from both groups showed no detectable antibodies against E. tarda. Overall, these data show that the NP-rOmpA vaccine produced higher antibody levels and had superior protection over the IWC-ET vaccine, showing that encapsulating OmpA in chitosan NPs confer improved protection against E. tarda mortality in L. fimbriatus. There is a need to elucidate the possible adjuvant effects of chitosan NPs and the immunological mechanisms of protective immunity induced by OMPs administered orally to fish.
