Live micro-encapsulated Brucella abortus vaccine strains offer enhanced protection and sustained immune response in BALB/c mice Mukherjee F.1,**, Prasad A.2,**, Rajendra L.3, Bahekar V.S.1, Ramalakhsmi B.4, Nagmani K.4, Rana S.K.1, Sharma G.K.5, Srinivasan V. A.6,* 1Research and Development Laboratory, National Dairy Development Board, Gachibowli, Hyderabad, 500032, Telangana, India 2Department of Bio-Technology, Jawaharlal Nehru Technological University; Research and Development Centre, Indian Immunological Limited, Gachibowli, Hyderabad, 500032, Telangana, India 3Plot No. 68. Flat No. 4A, Challa Pushpa Doyen Dacha Apartments, Shri Nagar Colony, Hyderabad, 500073 4Research and Development Centre, Indian Immunological Limited, Gachibowli, Hyderabad, 500032, Telangana, India 5National Dairy Development Board, Anand, 388001, Gujarat, India 6National Dairy Development Board, 33, Telecom Nagar, Gachibowli, Hyderabad, 500032, Telangana, India *For Correspondence-srinivasanva1948@gmail.com
**Authors contributed equally
Online published on 16 December, 2015. Abstract Two sustained release vaccine delivery formulations, micro-encapsulated live Brucella abortus vaccine strains S19 and RB51 in alginate microspheres, were analyzed for entrapment efficacy and in-vitro release kinetic studies. The level of protection offered to female BALB/c mice after sub-cutaneous (S/C) immunization with both encapsulated vaccine formulations 15 days after intra-peritoneal (I/P) challenge on 30th days post immunization (DPI) with wild type B. abortus 544 strain was significantly higher (P<0.01) compared to nonencapsulated live versions. In addition, the protection offered by the encapsulated RB51 formulation was superior (P<0.01) compared to encapsulated S19. The mean number of colony forming units (log10 CFU) persisting in spleen in all four experimental groups of immunized mice at 15 day post challenge (DPC) did not differ significantly. Subtle differences in the antibody isotype and cytokine response pattern were observed during the pre and the post challenge stage indifferent groups of mice immunized with encapsulated S19, encapsulated RB51, nonencapsulated S19 and RB51. Compared to nonencapsulated version and saline inoculated controls, the enhanced protection exhibited by micro-encapsulated vaccines was reflected in significantly different (P <0.01) IgG1, IgG2b, IgG3 titers in mice immunized with encapsulated RB51, but not with encapsulated S19 at 15 DPC; however, encapsulated S19 immunized group showed significantly different (P<0.01) IgG2a titers. Although, both the mice groups immunized with encapsulated S19 and RB51 elicited significantly higher (P<0.01) IFN-γ response compared to S19 and RB51 non-encapsulates and controls at 15 DPC, the difference (P<0.05) in IL-2 response could be observed in encapsulated RB51 immunized group but not in encapsulated S19. The salient features of prechallenge immune response in mice immunized with encapsulated S19 smooth strain were characterized by significantly elevated IgG1, IgG2a, IgG2b, IgG3 titers (P<0.05; P<0.05; P<0.01; P<0.01 respectively) at 30 DPI, also, IgG2a (P<0.05) and IgG2b (P<0.01) titers differed significantly as early as 7 DPI, accompanied by elevated IL-2 (P<0.05) at 21 DPI; while the encapsulated RB51 rough strain elicited enhanced IgG1 (P<0.05, P<0.05 and P<0.01) at 14, 21 and 30 DPI and IgG2b (P<0.01) response at 30 DPI. Overall comparison indicated that RB51 micro-encapsulated vaccine formulation is probably a potential candidate as it offered the best level of protection upon challenge and elicited most appropriate immune response. Top Keywords Brucella abortus, microencapsulation, vaccine, cytokines, antibody. Top |