Newcastle disease vaccine delivered through PLG microspheres induced protective immune responses in broiler chickens

S. Dandapat, Rajan, Debashish Banerjee, J.M. Kataria*, B. B. Dash* and G.C. Ram
Immunology Section *Division of Avian Diseases
Indian Veterinary Research Institute, Izatnagar-243122 (U.P.)
Email: [email protected]

The vaccine strain of Ranikhet ( Newcastle ) disease virus (RDF) was encapsulated in biodegradable poly-lactide-co-glycolide (PLG) microspheres by double emulsion solvent evaporation technique. Scanning electron microscopy revealed that the size of virus entrapped microparticles ranged from 1-10 m m and majority were of less than 2 m m. A single intranasal dose of the experimental microsphere vaccine containing 75 m g of viral antigen was able to induce both humoral as well as cell mediated immunity in poultry. The serum samples of the immunized chicks showed significantly higher levels of circulating IgG and HI-antibodies against the viral antigens as compared to unvaccinated control chicks up to 6-week post immunization with the peak HI-titre of (log 2) 6.0 and virus specific IgG level of (log 10) 3.84 at 3 rd wk PI. In serum neutralization test (SNT), protective levels of neutralizing antibodies (log 10 NI > 2.0) were detected up to 6-wk PI, which were comparable to that obtained with the conventional RDF vaccine. The intranasal delivery of microsphere vaccine formulation could also induce cell-mediated immunity showing the peak blastogenic response of peripheral blood lymphocytes with mean stimulation index (S.I.) value of (1.416 ± 0.034) at 3 rd wk PI, which was significantly (p<0.05) higher than that of the control group. In challenge studies, it was found that the single dose of ND vaccine delivered through PLG microspheres afforded protection up to 70% against the challenge infection with virulent RD virus (10 5.5 EID 50/0.2 ml), at 6 th wk post immunization, which was comparable to the conventional RDF vaccine.

Source : IPSACON-2005

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