Background: To accomplish successful vaccination, it is essential to design new strategies to produce vaccines that can effectively penetrate the cells particularly when the designed vaccine can be co-localized in an Antigen-Presenting Cell (APC) and produce more specific immune responses for antigen. Hence it is important to use vectors which can co-deliver antigen and adjuvant to APC and help increasing their absorption. Toll like receptors (TLRs) agonists are promising vaccine adjuvants which enhance and modulate innate as well as adaptive immune responses in great potentials.The use of nonviral vectors as delivery carriers for oligonucleotides and antigen, enhance vaccination responses. An effective way for co-delivery of antigen and CpG oligodeoxynucleotides (CpG ODN) as TLR9 agonist is to encapsulate both in one carrier to ensure that they both enter one cell.Methods:In this study, OVA protein as antigen was encapsulated in PLGA (poly-lactic-co-glycolic acid) which was covalently conjugated using amide chemistry to the surface of 10% covered polyethylenimine (PEI) followed by addition of CpG ODN which is a 22 mer oligonucleotide in order to produce a nanoparticulate vector for vaccine delivery .Results:The resulting complex was characterized in terms of size, zeta potential and the structure was confirmed by FT-IR spectroscopy. The vaccine delivery potentials of the resulting complex are under investigation.Conclusion: It was found that OVA protein encapsulated in PLGA covalently conjugated with PEI and followed by addition of CpG ODN non-covalently, could ideally be utilized as a nano-vector to sucessfully deliver vaccine into the desired cells

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