Aeromonas hydrophila OmpW PLGA Nanoparticle Oral Vaccine Shows a Dose-Dependent Protective Immunity in Rohu (Labeo rohita).
Aeromonas hydrophila is a Gram-negative bacterium that causes high mortality in different fish species and at different growth stages. Although vaccination has significantly contributed to the decline of disease outbreaks in aquaculture, the use of oral vaccines has lagged behind the injectable vaccines due to lack of proven efficacy, that being from primary immunization or by use of boost protocols. In this study, the outer membrane protein W (OmpW) of A. hydrophila was cloned, purified, and encapsulated in poly d,l-lactide-co-glycolic acid (PLGA) nanoparticles (NPs) for oral vaccination of rohu (Labeo rohita Hamilton). The physical properties of PLGA NPs encapsulating the recombinant OmpW (rOmpW) was characterized as having a diameter of 370-375 nm, encapsulation efficiency of 53% and -19.3 mV zeta potential. In vitro release of rOmpW was estimated at 34% within 48 h of incubation in phosphate-buffered saline. To evaluate the efficacy of the NP-rOmpW oral vaccine, two antigen doses were orally administered in rohu with a high antigen (HiAg) dose that had twice the amount of antigens compared to the low antigen (LoAg) dose. Antibody levels obtained after vaccination showed an antigen dose dependency in which fish from the HiAg group had higher antibody levels than those from the LoAg group. The antibody levels corresponded with post challenge survival proportions (PCSPs) and relative percent survival (RPS) in which the HiAg group had a higher PCSP and RPS than the LoAg group. Likewise, the ability to inhibit A. hydrophila growth on trypticase soy agar (TSA) by sera obtained from the HiAg group was higher than that from the LoAg group. Overall, data presented here shows that OmpW orally administered using PLGA NPs is protective against A. hydrophila infection with the level of protective immunity induced by oral vaccination being antigen dose-dependent. Future studies should seek to optimize the antigen dose and duration of oral immunization in rohu in order to induce the highest protection in vaccinated fish.
Department of Fisheries Microbiology, Karnataka Veterinary, Animal &amp; Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. saurabh.dubey@nmbu.no.|Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Adamstuen Campus, Ullev&#229;lseveien 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 &amp; Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. sangeethasivadas888@gmail.com.
Sangeetha Madambithara
SM
Sivadasan
UNESCO MIRCEN for Medical and MarineBiotechnology, Nitte University Centre for Science Education and Research, Nitte University, Deralakatte, Mangalore 575018, India. maitibiswajit@yahoo.com.
Biswajit
B
Maiti
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Adamstuen Campus, Ullev&#229;lseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway. joydeb.paul@nmbu.no.
Joydeb
J
Paul
Department of Fisheries Microbiology, Karnataka Veterinary, Animal &amp; Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. skgirisha@gmail.com.
Shivani Kallappa
SK
Girisha
Department of Fisheries Microbiology, Karnataka Veterinary, Animal &amp; Fisheries Sciences University, College of Fisheries, Mangalore 575002, India. mnvenu@rediffmail.com.
Moleyur Nagarajappa
MN
Venugopal
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Adamstuen Campus, Ullev&#229;lseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway. stephen.mutoloki@nmbu.no.
Stephen
S
Mutoloki
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Adamstuen Campus, Ullev&#229;lseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway. oystein.evensen@nmbu.no.
Øystein
Ø
Evensen
UNESCO MIRCEN for Medical and MarineBiotechnology, Nitte University Centre for Science Education and Research, Nitte University, Deralakatte, Mangalore 575018, India. karuna8sagar@yahoo.com.
Indrani
I
Karunasagar
Section of Aquatic Medicine and Nutrition, Department of Basic Sciences and Aquatic Medicine, Faculty of Veterinary Medicine, Norwegian University of Life Sciences, Adamstuen Campus, Ullev&#229;lseveien 72, P.O. Box 8146, NO-0033 Dep, Oslo 0454, Norway. hetroney.mweemba.munangandu@nmbu.no.
Hetron Mweemba
HM
Munang'andu
Aeromonas hydrophila; PLGA; nanoparticle; oral; outer membrane protein; rohu