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Mucosal application of cationic poly(d,l-lactide-co-glycolide) microparticles as carriers of DNA vaccine and adjuvants to protect chickens against infectious bursal disease

Negash, Tamiru, Liman, Martin, Rautenschlein, Silke
Vaccine 2013 v.31 no.36 pp. 3656-3662
Infectious bursal disease virus, T-lymphocytes, adsorption, antigens, application methods, bursa of Fabricius, chickens, eyes, gene expression, histopathology, infectious bursal disease, interferon-alpha, interleukin-2, interleukin-4, messenger RNA, mouth, neutralizing antibodies, oligodeoxyribonucleotides, plasmids, recombinant vaccines, specific pathogen-free animals, vaccine adjuvants, viruses
Infectious bursal disease virus (IBDV) is an immunosuppressive virus of chickens. The virus protein (VP) 2 induces neutralizing antibodies, which protect chickens against the disease. The aim of this study was to develop a cationic poly(d,l-lactide-co-glycolide) (PLGA) microparticle (MP) based IBDV-VP2 DNA vaccine (MP-IBDV-DNA) for chickens to be delivered orally and by eye drop route. The tested IBDV-VP2 DNA vaccines were immunogenic for specific-pathogen-free chickens and induced an antibody response after intramuscular application. Co-inoculation with a plasmid encoding chicken IL-2 (chIL-2) or CpG-ODN did not significantly improve protection against IBDV challenge. However, the application of a MP-IBDV-DNA vaccine alone or in combination with a delayed oral and eye drop application of cationic MP loaded with CpG-ODN or chIL-2 improved protection against challenge. The MP-IBDV-DNA-vaccinated chickens showed less pathological and histopathological bursal lesions, a reduced IBDV antigen load as well as T-cell influx into the bursa of Fabricius (BF) compared to the other groups (p<0.05). The addition of chIL-2 loaded MP improved challenge virus clearance from the BF as demonstrated by lower neutralizing antibody titers and reduced IL-4 and IFN-α mRNA expression in the bursa at 7 days postchallenge compared to the other challenged groups. Overall, the efficacy of the IBDV-DNA vaccine was improved by adsorption of the DNA vaccine onto cationic PLGA-MP, which also allowed mucosal application of the DNA vaccine.