Emulsified nanoparticles containing inactivated influenza virus and CpG oligodeoxynucleotides critically influences the host immune responses in mice.

• Published in: PLoS ONE
• Main Authors: Ming-Hsi Huang, Su-Chen Lin, Chia-Hsin Hsiao, Hsin-Ju Chao, Hung-Ren Yang, Chien-Chun Liao, Po-Wei Chuang, Huang-Pi Wu, Chiung-Yi Huang, Chih-Hsiang Leng, Shih-Jen Liu, Hsin-Wei Chen, Ai-Hsiang Chou, Alan Yung-Chih Hu, Pele Chong
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2010
• Subjects: Medicine; R; Science; Q; Whooper Swan
• Online Access: https://doi.org/10.1371/journal.pone.0012279; https://doaj.org/article/8af2a45793c74b95b348aab891684f90

Background Antigen sparing and cross-protective immunity are regarded as crucial in pandemic influenza vaccine development. Both targets can be achieved by adjuvantation strategy to elicit a robust and broadened immune response. We assessed the immunogenicity of an inactivated H5N1 whole-virion vaccine (A/Vietnam/1194/2004 NIBRG-14, clade 1) formulated with emulsified nanoparticles and investigated whether it can induce cross-clade protecting immunity. Methodology/principal findings After formulation with PELC, a proprietary water-in-oil-in-water nanoemulsion comprising of bioresorbable polymer/Span(R)85/squalene, inactivated virus was intramuscularly administered to mice in either one-dose or two-dose schedule. We found that the antigen-specific serum antibody responses elicited after two doses of non-adjuvanted vaccine were lower than those observed after a single dose of adjuvanted vaccine, PELC and the conventional alum adjuvant as well. Moreover, 5 microg HA of PELC-formulated inactivated virus were capable of inducing higher antibodies than those obtained from alum-adjuvanted vaccine. In single-dose study, we found that encapsulating inactivated virus into emulsified PELC nanoparticles could induce better antibody responses than those formulated with PELC-adsorbed vaccine. However, the potency was rather reduced when the inactivated virus and CpG (an immunostimulatory oligodeoxynucleotide containing unmethylated cytosine-guanosine motifs) were co-encapsulated within the emulsion. Finally, the mice who received PELC/CpG(adsorption)-vaccine could easily and quickly reach 100% of seroprotection against a homologous virus strain and effective cross-protection against a heterologous virus strain (A/Whooper swan/Mongolia/244/2005, clade 2.2). Conclusions/significance Encapsulating inactivated H5N1 influenza virus and CpG into emulsified nanoparticles critically influences the humoral responses against pandemic influenza. These results demonstrated that the use of PELC could be as antigen-sparing in preparation ...