Effect of adjuvant on pharmacokinetics, organ distribution and humoral immunity of hepatitis b surface antigen after intramuscular injection to rats

A Comprehensive review on Pharmacokinetic Studies of Vaccines: Impact of delivery route, carrier-and its modulation on immune response

The lack of knowledge about the absorption, distribution, metabolism, and excretion (ADME) of vaccines makes former biopharmaceutical optimization difficult. This was shown during the COVID-19 immunization campaign, where gradual booster doses were introduced.. Thus, understanding vaccine ADME and its effects on immunization effectiveness could result in a more logical vaccine design in terms of formulation, method of administration, and dosing regimens. Herein, we will cover the information available on vaccine pharmacokinetics, impacts of delivery routes and carriers on ADME, utilization and efficiency of nanoparticulate delivery vehicles, impact of dose level and dosing schedule on the therapeutic efficacy of vaccines, intracellular and endosomal trafficking and in vivo fate, perspective on DNA and mRNA vaccines, new generation sequencing and mathematical models to improve cancer vaccination and pharmacology, and the reported toxicological study of COVID-19 vaccines. Altogether, this review will enhance the reader's understanding of the pharmacokinetics of vaccines and methods that can be implied in delivery vehicle design to improve the absorption and distribution of immunizing agents and estimate the appropriate dose to achieve better immunogenic responses and prevent toxicities.

Conjugation of chitosan oligosaccharides via a carrier protein markedly improves immunogenicity of porcine circovirus vaccine

Porcine circovirus type 2 (PCV2)-associated diseases have led to huge economic losses in pig industry. Our laboratory previously found that conjugation of chitosan oligosaccharides (COS) enhanced the immunogenicity of PCV2 vaccine against infectious pathogens. In this study, an effective adjuvant system was developed by covalent conjugation of COS via a carrier protein (Ovalbumin, OVA) to further increase the immunogenicity of vaccine. Its effect on dendritic cells maturation was assessed in vitro and its immunogenicity was investigated in mice. The results indicated that, as compared to the PCV2 and COS-PCV2, COS-OVA-PCV2 stimulated dendritic cells to express higher maturation markers (CD80, CD86, CD40 and MHC class II) and remarkably promoted both humoral and cellular immunity against PCV2 by enhancing the lymphocyte proliferation and inducing a mixed Th1/Th2 response, including the increased production of PCV2-specific antibodies and raised levels of inflammatory cytokines. Furthermore, it displayed better immune-stimulating effects than the physical mixture of vaccine and ISA206 (a commercialized adjuvant). In conclusion, conjugation of COS via a carrier protein might be a promising strategy to enhance the immunogenicity of vaccines.

Vaccine adjuvant ginsenoside Rg1 enhances immune responses against hepatitis B surface antigen in mice

The adjuvant effect of ginsenoside Rg1 on immune responses against hepatitis B surface antigen (HBsAg) in mice was investigated. Female BALB/c mice were subcutaneously injected with saline or HBsAg antigen with or without Rg1 on days 7 and 21. Samples were collected 2 weeks after the boosting for the detection of anti-HBsAg immunoglobulin G (IgG) isotypes in sera and gamma interferon (IFN-γ) and interleukin-4 (IL-4) produced in splenocytes. The innate and adaptive immune responses were measured in mice immunized as described above. The results showed that ginsenoside Rg1 had adjuvant properties in stimulating IgG, splenocyte proliferation, and mRNA expression of cytokines IFN-γ and IL-4, as well as the expression of cell surface marker TLR4 in the HBsAg-immunized mice. These results indicate that Rg1 enhances both Th1 (IgG2b and IFN-γ) and Th2 (IgG1 and IL-4) responses. In addition, the TLR4 signaling pathway is involved in the adjuvant activities of ginsenoside Rg1.