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Objective To study the regulating effects of a novel CpG oligodeoxynuleotide and the synergistic effect of chitosan-nanoparticles (CNP) with CpG on immune responses of mice, which were used to develop a novel immunoadjuvant to boost immune response to conventional vaccines. Methods A novel CpG ODN containing 11 CpG motifs was synthesized and its bioactivities to stimulate the proliferation of lymphocytes of pig in vitro were detected. Then it was entrapped with CNP prepared in our laboratory by the method of ionic cross linkage, and immunized Kunming mice were co-inoculated with paratyphoid vaccine. The peripheral blood was collected weekly from the tail vein of inoculated mice to detect the contents of IgG, IgA, IgM, and specific antibody against salmonella as well as the levels of interleukin-2 (IL2), IL-4, and IL-6 by SABC-ELISA assay. The numbers of leucocytes, monocytes, granuloytes, and lymphocytes were calculated separately using the routine method. The experimental mice were orally challenged with virulent salmonella 35 days after inoculation. Results This CpG ODN could remarkably provoke the proliferation of lymphocytes of pig in Vitro in contrast with the control (P<0.05). Compared with those of the control, immunoglobulins, including IgG, IgA, IgM, and specific antibodies to paratyphoid vaccine, increased significantly in sera from the CpG or CpG-CNP-vaccinated mice (P<0.05). IL-2, IL-4, and IL-6 increased remarkably in sera from immunized mice (P<0.05). The leucocytes, monocytes, granuloytes, and lymphocytes of the mice immunized with CpG or CpG-CNP were also increased in number (P<0.05). After the challenge, these immunity values were elevated in the mice vaccinated with CpG or CpG-CNP. The immunized mice all survived, while the control mice fell ill with evident lesions with diffuse hemorrhage in stomach, small intestine, and peritoneum. Conclusions CpG ODN entrapped with CNP is a promising effective immunoadjuvant for vaccination, which promotes humoral and cellular immune responses, enhances immunity and resistance against salmonella by co-administration with paratyphoid vaccine. [ABSTRACT FROM AUTHOR]

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. coli infection, and can be utilized as an effective adjuvant to improve the immunoprotection and resistance of porcine against infectious disease. [ABSTRACT FROM AUTHOR]