Table 1.
Summary of polymers for vaccine carriers and adjuvants.
| Polymers | Compounds | Virus | Animal model | Effect | Advantage | References |
|---|---|---|---|---|---|---|
| PLGA | CpG ODN 2007 | Infectious bronchitis virus (IBV) | Chickens | Improved innate and long-term immunostimulatory effects in vivo and in vitro | Degradability, renewable, non-toxic, and completely biodegradable and recognized by the Food and Drug Administration (FDA) | [67] |
| PLGA | STING agonists | Middle East respiratory syndrome coronavirus (MERS-CoV) | C57BL/6 mice | Coordinated delivery of antigen and adjuvant in vitro and in vivo; significantly enhances antigen-specific humoral and cellular responses | [68] | |
| DSPE-PEG-maleimide | MERS-CoV RBD | |||||
| PLGA | PEDV killed vaccine antigens (KAg) | Porcine epidemic diarrhea virus (PEDV) | Pregnant sows and suckling piglets | Induced systemic and mucosal immunity; efficiently protected suckling piglets against challenge with PEDV | [69] | |
| PLGA | Inactivated PRRSV vaccine (NP-KAg) | Porcine reproductive and respiratory syndrome virus (PRRSV) | Piglets | Reduce greatly the required vaccine dose; the entrapped antigen was released at a much slower rate and triggers a robust effect and memory immune response | [70] | |
| PLGA | DNA vaccines | Newcastle disease virus (NDV) | Chickens | Induces stronger immune responses, and achieve sustained release | [71] | |
| PLGA | Killed PRRSV vaccine (Nano-KAg) | PRRSV | Pigs | The potential to generate anti-PRRSV immune response and in better clearance of viremia | [72] | |
| PEG-PLGA | Diphyllin | Feline coronaviruses (FCoVs) | Mice | Higher safety and increased inhibitory activity against FIPV | [73] | |
| O-2′-HACC | Live Newcastle disease vaccine | NDV | Chickens | Long release, low toxicity, high safety | High antimicrobial activity, low toxicity, and a high safety level | [74] |
| N-2-HACC-CMC | NDV/La Sota + IBV/H120 | NDV and IBV | Chickens | Induces greater IgG and IgA antibody potency; significantly promotes lymphocyte proliferation and induces higher levels of cytokines | N-2-HACC was more cost-effective than O-2′-HACC, and N-2-HACC has superior water solubility and more suitable size than chitosan and O-2′-HACC | [75] |
| NDV F gene plasmid DNA with C3d6 molecular adjuvant | NDV | Chickens | Increased production of anti-NDV IgG and IgA antibodies; significantly stimulated lymphocyte proliferation, triggering higher levels of IL-2, IL-4, and IFN-γ | [76] | ||
| HACC and SCS | As vaccine adjuvants to prepare NDV-loaded nanoparticles | NDV | Chickens | Qualified levels of humoral immunity (HI > 5) and higher levels of cellular immunity compared with the commercial oil emulsion vaccine; these nanoparticles provide 100% protection against virulent NDV | SCS nanoparticles were not active as CS and HACC nanoparticles for the adjuvant effect of NDV | [77] |
| Chitosan | Inactivated NDV vaccine | NDV | Chickens | Adjuvant effects of Chitosan, CS particles efficiently changed mucosal and humoral immunity and protective activity | Chitosan has superior biocompatibility and biodegradability and can bind to negatively charged proteins or DNA plasmids through the electrostatic interaction, forming polymer composites to protect proteins and DNA from degradation | [78] |
| Live NDV vaccine | NDV | Chickens | Induced greater protection of immunized specific pathogen | [79] | ||
| NDV F gene deoxyribonucleic acid (DNA) vaccine | NDV | Pathogen-free chickens | Induced significantly higher mucosal and humoral immune responses; protect the plasmid DNA from degradation and help the expression of the plasmid DNA encapsulated | [80] | ||
| NDV vaccines | NDV | Chickens | Produce higher mucosal immunity titers by taking vaccine orally; meanwhile, it can induce humoral and cell-mediated immune response and mucosal immunity strongly | [81] | ||
| Chitosan (CS)-coated poly(lactic-co-glycolic) acid (PLGA) | DNA (the F gene) of NDV | NDV | Chickens | The immunogenicity and protective immunity can be improved | CS reduces burst release of encapsulated proteins or DNA; increases the stability of biomolecules; enhances zeta potential reversal and promotes cell adhesion and retention of the delivery system at the target site; provides the possibility of conjugating targeting ligands to free amino acids on the surface | [82] |
| Polyethylenimine (PEI) | SARS DNA vaccine | Severe acute respiratory syndrome (SARS-CoV) | BALB/c mice | PEI/pci-S nanoparticles induce antigen-specific humoral and cellular immune responses | High transfection efficiency and buffering capacity; PEI is a very effective gene delivery vehicle for lung transfection producing high antibody titers against the encoded protein | [83] |
| pci-S/PEI | SARS DNA vaccine | SARS-CoV | BALB/c mice | Induce antigen-specific humoral and cellular immune responses | [84] |