Edwardsiella tarda OmpA Encapsulated in Chitosan Nanoparticles Shows Superior Protection over Inactivated Whole Cell Vaccine in Orally Vaccinated Fringed-Lipped Peninsula Carp (Labeo fimbriatus).
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) ofEdwardsiella tardawas encapsulated in chitosan NPs (NP-rOmpA) and used for oral vaccination ofLabeo 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 cellE. 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 cellE. 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 forE. tardagrowth 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 againstE. 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 againstE. tardamortality inL. 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.
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. saurabh.dubey@nmbu.no.|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. saurabh.dubey@nmbu.no.
Saurabh
S
Dubey
Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, India. kirankle84@gmail.com.
Kiran
K
Avadhani
Department of Pharmaceutics, Manipal College of Pharmaceutical Sciences, Manipal University, Manipal 576104, Karnataka State, India. ssmutalik@yahoo.com.
Srinivas
S
Mutalik
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. sangeethasivadas888@gmail.com.
Sangeetha Madambithara
SM
Sivadasan
UNESCO MIRCEN for Marine Biotechnology, Nitte University Centre for Science Education and Research, Paneer Campus, Deralakatte, Mangalore 575018, India. maiti.b@nitte.edu.in.
Biswajit
B
Maiti
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. skgirisha@gmail.com.
Shivani Kallappa
SK
Girisha
Department of Fisheries Microbiology, Karnataka Veterinary, Animal & Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. mnvenu@rediffmail.com.
Moleyur Nagarajappa
MN
Venugopal
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. stephen.mutoloki@nmbu.no.
Stephen
S
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. oystein.evensen@nmbu.no.
Øystein
Ø
Evensen
UNESCO MIRCEN for Marine Biotechnology, Nitte University Centre for Science Education and Research, Paneer Campus, Deralakatte, Mangalore 575018, India. indrani.karunasagar@nitte.edu.in.
Indrani
I
Karunasagar
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. hetroney.mweemba.munangandu@nmbu.no.
Hetron Mweemba
HM
Munang’andu
carp; chitosan; nanoparticle; oral; outer membrane protein; vaccination