CpG oligodeoxynucleotide synergizes innate defense regulator peptide for enhancing the systemic and mucosal immune responses to pseudorabies attenuated virus vaccine in piglets in vivo.

Oligonucleotides containing CpG motifs (CpG ODN) are strong adjuvants for humoral and cellular immune responses in mice, and innate defense-regulator peptides (IDRs) are known to facilitate the uptake of antigens into antigen presenting cells (APCs), but data on synergistic effects of CpG and IDRs in piglets are scarce. In this report, the combination of porcine-specific CpG ODN and HH2 (a kind of IDR which was selected for its better synergy with CpG ODN) was used as immunoadjuvant to enhance the immune responses of the newborn piglets to Pseudorabies attenuated virus (PRV) vaccine. The titers of specific antibodies and serum IgG1/IgG2 subtypes to PRV vaccine, interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), IL-12 and IL-4 were examined to identify the immune responses of the newborn piglets. The results showed that piglets immunized intranasally (IN) and subcutaneously (SC) with PRV vaccine and CpG-HH2 complex both presented high titers of PRV-specific antibodies and IgG2 isotype, a Th1-dominated (IFN-γ and IL-12) cytokine profiles, high levels of IgA in saliva, broncheoalveolar lavage (BAL) and intestinal washings. The results suggested that, CpG-HH2 complex augmented systemic (IgG in serum) and mucosal (IgA in saliva, BAL and intestinal washings) immune responses against antigen. CpG-HH2 complex stimulated both T-helper type1 (Th1) (IgG2) and Th2 (IgA) responses when delivered IN, and IN route could induce stronger mucosal immune responses than SC route. All these data indicate that CpG-HH2 complex is a potential effective adjuvant for the PRV vaccine in newborn piglets.

CpG oligodeoxynucleotide promotes protective immunity in the enteric mucosa and suppresses enterotoxigenic E. coli in the weaning piglets.

CpG oligodeoxynucleotide (CpG ODN) has been described as an effective activator of the innate immune system, with potential to protect against infection caused by a range of pathogens in a non-specific manner. We therefore investigated if intranasal (IN), oral (OR)-mucosal, and intramuscular (IM)-systemic administrations of CpG ODN without antigen codelivery could all enhance innate immunity in the enteric mucosa and control the extent of enterotoxigenic Escherichia coli (ETEC) infection in weaning piglets. Here our data showed that CpG ODN dosed by IN, OR or IM routes protected weaning piglets against a subsequent challenge with ETEC. The level of protection was greater when CpG ODN was administered IN and OR than IM, demonstrating a clear relationship between the route of CpG dosing and protection. IN and OR treatments with CpG ODN reduced bacterial load in the phases at days 3-5 post challenge. The CXC chemokine (CXCL10 and CXCL11) and CC chemokine (CCL4 and CCL5) mRNA expressions were elevated in the intestinal tissues from animals treated IN or OR with CpG ODN compared to untreated controls. Significantly enhanced mRNA expressions for cathelicidins (PR-39 and protegrin-1), but moderately for ß-defensin (pBD1 and pBD2), were observed in IN or OR CpG-treatments. Also, significant production of cytokines (IL-12, IFN-γ, and MCP-1) and F4-specific antibodies (IgG/IgA) was detected in intestinal washings following IN and OR CpG-treatments. In contrast, IM delivery induced marked production of sera F4-specific antibodies. It was possible that these chemokines, cytokines, cathelicidins and antibodies played a role in the clearance of ETEC. These findings suggested that IN or OR administration of CpG ODN without antigen codelivery might represent a valuable strategy for induction of innate immunity against ETEC infection.

Synthetic innate defence regulator peptide enhances in vivo immunostimulatory effects of CpG-ODN in newborn piglets.

The in vivo immunoadjuvant effects of CpG oligodeoxynucleotides (CpG-ODN) have been studied extensively in mice and relatively fewer studies have been done in piglets. But so far, the innate immunostimulatory effects of CpG-ODN combination with innate defense-regulator peptides (IDRs) have not been demonstrated. The purpose of this study is to determine the potential effects of CpG-ODN with IDR in newborn piglets. The immunostimulatory abilities of four selected IDRs were compared, among them HH2 showed best immunostimulatory effects in newborn piglets. Hereafter, the abilities of CpG-ODN combined with HH2 to enhance innate immune responses were examined in newborn piglets. The complex of HH2 and CpG-ODN could induce much stronger Th1 cytokine and chemokine responses than HH2 or CpG-ODN alone. HH2-CpG-ODN immunized piglets showed higher B cell percentage in PBMCs than CpG-ODN alone. These in vivo data demonstrated for the first time that subcutaneously (SC) administration of CpG-ODN combined with HH2 is efficient to stimulate innate immune system in newborn piglets.