A pH-Triggered self-releaseing humic acids hydrogels loaded with porcine interferon α/γ achieves anti-PRV effects by oral administration

Abstract Interferon α (IFNα) and interferon γ (IFNγ) are cytokines that mediate important biological functions, including antiviral activity and immune regulation. However, the function of monomer IFN was limited and the administration route completely depends on injection. To solve this problem, recombinant porcine IFN-α and IFN-γ fusion protein (rPoIFNα/γ) was expressed, purified, and used to develop an effective oral rPoIFNα/γ humic acid hydrogel delivery system triggered by pH to protect the IFNα/γ from gastric acid destruction. Neither the humic acid hydrogel nor rPoIFNα/γ showed cytotoxicity in vitro for porcine kidney-15 (PK-15) cells. rPoIFNα/γ inhibited the replication of vesicular stomatitis virus (VSV) and pseudorabies virus (PRV), with an antiviral activity of approximately 104 U/mL. Scanning electron microscopy revealed that the humic acid (HA) hydrogel had a loose and porous honeycomb structure. rPoIFNα/γ was adsorbed by the hydrogel (IFNα/γ@PAMgel) and measured using Fourier transform infrared spectroscopy, and the results indicated a good IFN-loading effect. In vitro experiments showed that IFNα/γ@PAMgel swelled and released the IFNα/γ rapidly at pH 7.4 but not at pH 1.2. Mice oral administered IFNα/γ@PAMgel had enhanced proliferation and differentiation of CD4+ and CD8+ cells, whereas mice infected with PRV and treated with IFNα/γ@PAMgel had increased interferon stimulating genes (ISGs) transcription levels in the serum, lower mortality, lower viral loads in different tissues, and lower levels of organ damage. Conclusively, this study demonstrates that oral administered IFNα/γ@PAMgel has antiviral and immunomodulatory effects and is a potential antiviral agent for PRV infection.