Abstract
The protection of current influenza vaccines is limited due to the viral antigenic shifts and antigenic drifts. The universal influenza vaccine is a new hotspot in vaccine research that aims to overcome these problems. Polydopamine (PDA), a versatile biomaterial, has the advantages of an excellent biocompatibility, controllable particle size, and distinctive drug loading approach in drug delivery systems. To enhance the immunogenicities and delivery efficiencies of H9N2 avian influenza virus (AIV) epitope peptide vaccines, PDA nanoparticles conjugated with the BPP-V and BP-IV epitope peptides were used to prepare the nano BPP-V and BP-IV epitope peptide vaccines, respectively. The characteristics of the newly developed epitope peptide vaccines were then evaluated, revealing particle sizes ranging from approximately 240 to 290 nm (PDI<0.3), indicating that the synthesized nanoparticles were stable. Simultaneously, the immunoprotective effects of nano BPP-V and BP-IV epitope peptide vaccines were assessed. The nano BPP-V and BP-IV epitope vaccines, especially nano BP-IV epitope vaccine, quickly induced anti-hemagglutinin (HA) antibody production and a sustained immune response, significantly promoted humoral and cellular immune responses, reduced viral lung damage and provided effective protection against AIV viral infection. Together, these results reveal that PDA, as a delivery carrier, can improve the immunogenicities and delivery efficiencies of H9N2 AIV nano epitope vaccines, thereby providing a theoretical basis for the design and development of PDA as a carrier of new universal influenza vaccines.
Highlights
H9N2 avian influenza virus (AIV), is a low-pathogenicity virus that has attracted substantial attention due to its wide host range [1], high level of genetic diversity due to reassortment [2] and avian-to-human transmission [3], is a serious threat to the poultry industry and human health [4]
PDA was formed into a black organic biopolymer by dopamine oxidation and self-polymerization under basic oxygen conditions as determined by transmission electron microscopy (TEM)
PDA nanoparticles were bound to the H9N2 AIV epitope peptide coupled with BPP-V or BP-IV to form the nano BPP-V and BPIV epitope vaccines, which exhibited spherical organic polymers (Figures 3A–D)
Summary
H9N2 avian influenza virus (AIV), is a low-pathogenicity virus that has attracted substantial attention due to its wide host range [1], high level of genetic diversity due to reassortment [2] and avian-to-human transmission [3], is a serious threat to the poultry industry and human health [4]. Vaccination is the most effective measure to prevent influenza virus infections [5]. Antigenic drifts and shifts allow viruses to evade the immune systems to their hosts, resulting in mismatches and low vaccine effectiveness [6], and a universal influenza vaccine is needed. A previous study has shown that conserved epitopes in different influenza virus strains are very promising as vaccine immunogens [7]. The immune responses induced by conserved antigens are usually weak, and adjuvants are needed to enhance their potency. Delivery of protein antigens is challenging due to their fast degradation and diffusion [8]
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