Platycodin D Improves the Immunogenicity of Newcastle Disease Virus‐Based Recombinant Avian Influenza Vaccine in Mice

Abstract

The development of an effective influenza vaccine is urgently important for controlling outbreaks of the highly pathogenic avian influenza virus (HPAIV) and reducing the impact of pandemics. The use of an adjuvant in such a vaccine can significantly contribute to improve the immunogenicity. To explore a novel and safe adjuvant for improving the potency of influenza vaccines, platycodin D (1), a saponin from the root of Platycodon grandiflorum, was evaluated for the adjuvant potentials on the specific cellular and humoral immune responses to Newcastle disease virus-based recombinant avian influenza vaccine (rL-H5) in mice. Compound 1 significantly promoted the concanavalin A (Con A)-, the lipopolysaccharide (LPS)-, and the antigen-induced splenocyte proliferation and enhanced the serum antigen-specific IgG, IgG1, IgG2a, and IgG2b antibody titers (P<0.05, P<0.01, or P<0.001) in mice immunized with rL-H5. The mRNA expressions of Th1/Th2 cytokines (IFN-gamma and IL-10) and transcription factors (T-bet and GATA-3) in splenocytes were also markedly up-regulated by 1, compared with the control group immunized with rL-H5 alone (P<0.01 or P<0.001). In addition, 1 remarkably increased the killing activities of natural killer (NK) cells from splenocytes in the immunized mice (P<0.05), which may have important implications for the vaccination against the avian influenza virus. We concluded that 1 could improve the immunogenicity of the rL-H5 vaccine by enhancing both humoral and cellular immune responses in mice, and that 1 is a promising adjuvant for influenza vaccines.

Structure–function relationship of the saponins from the roots of Platycodon grandiflorum for hemolytic and adjuvant activity

“…The splenocytes prepared as previously described [37] were seeded into four wells of a 96-well flat-bottom microtiter plate at 5 × 10 6 cells/ml in 100 μl complete medium, thereafter Con A (final 1:1 2:1 5: …”

“…The activity of NK cells in splenocytes in the immunized mice was measured as previously described [37]. K562 cells were used as target cells and seeded in 96-well U-bottom microtiter plate at 2 × 10 4 cells/ well in RPMI 1640 complete medium.…”

“…H5Ag-specific IgG, IgG1, IgG2a, and IgG2b antibodies in sera were detected by an indirect ELISA as previously described [37]. In brief, microtiter plate wells were coated with 100 μl H5Ag solution (1 HAU/ml in 50 mM carbonate-bicarbonate buffer, pH 9.6) for 24 h at 4°C.…”

Vaccine Technologies Against Avian Influenza: Current Approaches and New Directions

“…183 184 Platycodin D, another saponin derived from Platycodon grandiflorum, has shown adjuvant potential with recombinantly produced H5. 185 Recent advances in molecular and structural biology have led to targeted approaches to stimulate innate immune cells through pattern recognition receptors (PRRs) such as toll-like receptors (TLRs), RIG-1-like receptors (RLRs), NOD-like receptors (NLRs), and C-type lectin receptors (CLRs). 186 187 Stimulating PRRs with ligands in conjunction with immunogen delivery provides a mechanism to enhance the resulting immune response.…”

The Effects of Platycodin D, a Saponin Purified from Platycodi Radix, on Collagen‐Induced DBA/1J Mouse Rheumatoid Arthritis

“…In China and Korea, the fresh roots of P. grandiflorum have been eaten as pickles for preventing obesity [13]. Platycodin D is a major pharmacological constituent of Platycodi Radix [14], and it has been showen the antidiabetic [14–16], anti-inflammatory [17–19], anticancer [20, 21], antinociceptive [22, 23], and immunomodulatory [24, 25] activities.…”