A novel chitosan CpG nanoparticle regulates cellular and humoral immunity of mice.
OBJECTIVE
To develop a safe and novel immunoadjuvant to enhance the immunity and resistance of animals against E. coli infection.


METHODS
An 88-base immunostimulatory oligodeoxynuleotide containing eleven CpG motifs (CpG ODN) was synthesized and amplified by PCR. The chitosan nanoparticle (CNP) was prepared by ion linking method to entrap the CpG ODN that significantly promotes the proliferation of lymphocytes of pig in vitro. Then the CpG-CNP was inoculated into 21-day old Kunming mice, which were orally challenged with virulent K88/K99 E. Coli 35 days after inoculation. Blood was collected from the tail vein of mice on days 0, 7, 14, 21, 28, 35, 42, and 49 after inoculation to detect the changes and content of immunoglobulins, cytokines and immune cells by ELISA, such as IgG, IgA, IgM, IL-2, IL-4, and IL-6.


RESULTS
The CpG provoked remarkable proliferation of lymphocytes of pig in vitro in comparison with that of control group (P < 0.05). The inoculation with CpG-CNP significantly raised the content of IgG, IgM, and IgA in the sera of immunized mice (P < 0.05). The levels of IL-2, IL-4, and IL-6 in the mice significantly increased in comparison with those in controls (P < 0.05), so was the number of white blood cells and lymphocytes in immunized mice. The humoral and cellular immunities were significantly enhanced in immunized mice, which resisted the infection of E. coli and survived, while the control mice manifested evident symptoms and lesions of infection.


CONCLUSIONS
CpG-CNP can significantly promote cellular and humoral immunity and resistance of mice against E. coil infection, and can be utilized as an effective adjuvant to improve the immunoprotection and resistance of porcine against infectious disease.
Wu
Kai-Yuan
KY
Key Labortory for Bio-Resource and Eco-Environment of Education Ministry, Life Science College, Sichuan University, Chengdu 610064, Sichuan, China.
Wu
Mei
M
Fu
Man-Liang
ML
Li
Hui
H
Yang
Yi
Y
Zhang
Huan
H
Cheng
Chi
C
Wang
Ze-Zhou
ZZ
Wang
Xiu-Ying
XY
Lü
Xue-Bing
XB
Liu
Di-Guang
DG
Li
Hua
H
Gao
Rong
R
D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood*; D001672:Biocompatible Materials / Q000008:administration & dosage; D048271:Chitosan / Q000008:administration & dosage*; D018899:CpG Islands; D004926:Escherichia coli / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D005260:Female; D007111:Immunity, Cellular; D007378:Interleukins / Q000096:biosynthesis; D008213:Lymphocyte Activation; D051379:Mice; D053758:Nanoparticles; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage*; D013552:Swine; D014611:Vaccination
D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D001672:Biocompatible Materials; C408982:CPG-oligonucleotide; D007378:Interleukins; D009838:Oligodeoxyribonucleotides; D048271:Chitosan