Improvement of the immunity of pig to Hog cholera vaccine by recombinant plasmid with porcine interleukin-6 gene and CpG motifs
Introduction
Classical swine fever (CSF) or hog cholera is one of the most devastating porcine haemorrhagic viral diseases. Outbreaks of CSF usually lead to significant losses in many countries worldwide [1]. CSF virus (CSFV) mainly infects endothelial cells and macrophages and at the same time promotes bystander apoptosis of the surrounding T cells, causing strong immune suppression and high mortality rates [2], [3], [4], [5]. Presently, novel vaccine and adjuvant is critical for enhancing immunity and resistance of pig against various infections. Vaccinations are frequently compromised due to rapid mutation of virus and bacteria.
Nowadays adjuvant is still important for boosting immunity and improving resistance in animals. Traditional adjuvants are mainly consisting of chemical molecule and microbial components, such as Al (OH)3, BCG and incomplete Freund's adjuvant, derived bacteria and plant components [6]. Recently cytokines had been utilized as new effective adjuvants [7], [8]. Moreover, pig Interleukin (IL-6) gene was ever proved to be able to enhance the immune responses of animal [9], which was one of key cytokines balancing between inflammation and the immune responses during the infection or injury process [10]. CpG motifs were also reported to represent another emerging adjuvant to strengthen the innate immunity of animal. The unique unmethylated CpG motifs could activate B cells, dendritic cells (DCs), NK T cells and monocytes and play an important role in infection and vaccination [11], [12]. Clinical studies demonstrate that CpG could be applied in therapy against infectious diseases, cancer, asthma and allergy [13]. The adjuvant activity of CpG ODN was demonstrated in humans and numerous animal species [14], [15], [16]. But they are usually not safe or effective enough to provoke strong and persistent immunoprotection in animals against most infectious diseases, especially immune defective diseases. There is pressing need to develop novel strong adjuvant to improve immunity and enhance protection against infectious diseases.
Until now, there are few reports about synergetic effects between IL-6 and CpG motifs, which were once employed to enhance immune responses of mice in vivo in our lab [17], [18]. Therefore, the present experiment was firstly carried out to detect the modulation of pig IL-6 and CpG motifs on the immune responses of pig to swine fever vaccine for the sake of developing a safer and more effective adjuvant to enhance immunity to conventional vaccines and facilitating the control of infectious diseases of animals.
Section snippets
Hog cholera vaccine
The vaccine is rabbit-attenuated Swine fever virus (provided by Chengdu Medicine and Appliances Factory, China), and employed in this experiment as conventional vaccine, which are extensively utilized to intramuscularly immunize swine in China to prevent Hog cholera.
VPIL6C (VR1020-PIL6-CpG)
Plasmid VR1020, provided by Vical Company of America, is used as the eukaryotic expression vector. Pig interleukin-6 gene (PIL-6) and CpG motifs were cloned and inserted into the VR1020; the recombined plasmid was named as VPIL6C in
Identification of VPIL6C-CNP
Observation by transmission electron microscopy elucidates that most of VPIL6C-CNP is spherical. Analysis by Zetasizer 3000 HS/IHPL shows that the average diameter of granule is 155 nm. Ranged from 132 to 230 nm, the dispersion rate is 0.22; zeta potential +17.6 mV, suggesting that the CNPs are positively charged, and the package rate of plasmids by CNP is over 98%.
Amount of specific antibody
14 days post inoculation, the amount of antibody to rabbit-attenuated swine fever virus significantly increased in the sera of the
Discussion
Classical swine fever (CSF) is a highly contagious disease of swine caused by CSFV, an enveloped positive sense, single-strand RNA Pestivirus in the flaviviridae family [22]. Most piglets suffer acute infection to die or survive by producing specific antibody to CSFV. In order to avoid or reduce the economic loss, effective vaccination and strict sanitation measures are critical for the control of outbreak of classical swine fever. There is a clear demand to construct safe and efficient novel
Acknowledgements
This research was supported by the grants from National Natural Science Foundation of China (grant no. 30170703 and 30571359), Outstanding Scholar and Key project of Science and Technology of Sichuan Province. We thank Dr. Guang-De Feng and Kai-YuanWu for their technical assistance.
References (33)
- et al.
Clinical signs and epidemiology of classical swine fever: a review of new knowledge
Vet J
(2003) - et al.
Virus antigen expression and alterations in peripheral blood mononuclear cell subpopulations after classical swine fever virus infection
Vet Microbiol
(1999) - et al.
Adjutants-a classification and review of their modes of action
Vaccine
(1997) - et al.
New approaches in vaccine development
Immunol Today
(1998) - et al.
Regulating effect of pig interleukin-6 gene and CpG motifs on immune responses to pig trivalent vaccines in mice
Res Vet Sci
(2004) - et al.
Cytokines chaos and complexity
Immunity
(1999) - et al.
CpG-containing oligodeoxynucleotides, in combination with conventional adjuvants, enhance the magnitude and change the bias of the immune responses to aherpesvirus glycoprotein
Vaccine
(2002) - et al.
CpG motifs as immune adjuvants
Vaccine
(1999) - et al.
Promotion of immunity of mice to Pasteurella multocida and hog cholera vaccine by pig interleukin-6 gene and CpG motifs
Comp Immunol Microbiol Infect Dis
(2009) - et al.
Porcine interleukin-2 gene encapsulated in chitosan nanoparticles enhances immune response of mice to piglet paratyphoid vaccine
Comp Immunol Microbiol Infect Dis
(2007)
Evaluation of the bacterial endotoxin test for quantification of endotoxin contamination of porcine vaccines
Biologicals
Genetic typing of classical swine fever virus
Vet Microbiol
Interleukin-6 in biology and medicine
Adv Immunol
CpG-containing oligodeoxynucleotides augment and switch the immune responses of cattle to bovine herpesvirus-1 glycoprotein D
Vaccine
Chitosan–DNA nanoparticles as gene carriers: Synthesis, characterization and transfection efficiency
J Control Release
Mesenchymal stem cells, MG63 and HEK293 transfection using chitosan-DNA nanoparticles
Biomaterials
Cited by (11)
Chitosan-based nanoparticles: An overview of biomedical applications and its preparation
2019, Journal of Drug Delivery Science and TechnologyCitation Excerpt :Attempts have been made to form new therapeutic approach that can restore immunocompetence in cancer patients. VPIL6C plasmids encoding porcine IL-6 and CpG are packaged into chitosan NPs to enhance humoral and cellular immunities [244]. CSNPs have been developed to deliver bovine herpesvirus and to enhance cellular immunity [245].
Polysaccharides as vaccine adjuvants
2018, VaccineCitation Excerpt :Chitosan NPs can effectively encapsulate antigen and enhance the activation of macrophages and dendritic cells (DCs), and antigen encapsulated in the chitosan NPs is superior to soluble antigen in inducing humoral and cell-mediated antigen-specific immune responses [27,28]. VPIL6C plasmids encoding porcine IL-6 and CpG are packaged into chitosan NPs to enhance humoral and cellular immunities [29]. Chitosan NPs are prepared to perform mucosal delivery of bovine herpesvirus and enhance cellular immunity [30].
Enhancement of immune response of piglets to PCV-2 vaccine by porcine IL-2 and fusion IL-4/6 gene entrapped in chitosan nanoparticles
2018, Research in Veterinary ScienceCitation Excerpt :IL-4 can influence humoral and cellular immune responses, such as the production, class switching and secretion of immunoglobulin (Pasquini et al., 1997; Paul, 2015); IL-6 has been shown to promote interleukin gene expression, B cell differentiation, T cell activation, and to play an important role in acute phase responses (Kishimoto, 2010; Kopf et al., 1994). We have previously demonstrated that pig IL-2 or IL-6 with CpG immunostimulatory sequences shuffled gene (Li et al., 2011; Yang et al., 2010), could effectively enhance animal resistance against pathogen infection. Moreover, the fusion protein of pig IL-4 and IL-6 can induce stronger proliferation of pig lymphoblasts than IL-4 and IL-6 individually (Yang et al., 2013; Zhang et al., 2007).
Interleukin-6: A promising cytokine to support liver regeneration and adaptive immunity in liver pathologies
2018, Cytokine and Growth Factor ReviewsCitation Excerpt :Mice infected with influenza virus exhibited an enhanced protective response when immunized with influenza virus DNA vaccine in combination with IL-6 as a molecular adjuvant compared to a DNA vaccine alone [129]. Similarly, in a porcine model of swine flu, the titres of IgG and IgA, levels of IFN-γ and magnitude of CD8T cell responses were significantly increased in peripheral blood when the vaccine was combined with IL-6 [130]. Recently a study demonstrated that mice administered a single intramuscular dose of recombinant rabies virus expressing canine IL-6 generated higher titres of anti-rabies virus antibodies compared to the parent strain of virus [131].
Expression of interleukin-6 by a recombinant rabies virus enhances its immunogenicity as a potential vaccine
2017, VaccineCitation Excerpt :It was also confirmed that antibodies against porcine circovirus type 2 (PCV2) and percentages of CD3+CD8+ peripheral blood T lymphocytes were significantly higher in mice immunized with a PCV2 DNA vaccine and IL6 than in animals that did not receive IL6 [17]. Furthermore, levels of antibodies against classical swine fever virus, IgG, IgA, IFN-γ, and CD8+ T cells in peripheral blood were higher if the vaccine used to immunize piglets was combined with IL6 [18]. Previous research implied that IL6 might also fulfil its function in heterologous tissues and animals of other species [14,15].
The porcine innate immune system: An update
2014, Developmental and Comparative Immunology
- 1
These authors contribute equally to the research.
- 2
Biology group of North Sichuan Medical College, Nan Chong 637007, Sichuan, China.
- 3
Bioengineering Department of Sichuan University of Science & Engineering, Zigong 643000, China.
- 4
Animal Academy of Sichuan province, Chengdu 610035, China.