Antiviral and immunomodulatory effects of Siji antiviral mixture against H9N2 avian influenza virus infection in chickens.

The H9N2 subtype avian influenza virus (AIV) is common in poultry and poses significant risks to both the poultry industry and public health. Current control strategies for H9N2 AIV predominantly rely on vaccination; however, these approaches are often undermined by the continuous antigenic drift of hemagglutinin under the pressure of antibodies. This study evaluated the antiviral efficacy of Siji Antiviral Mixture (SAM) against H9N2 infection in specific pathogen-free chickens. Compared with the infected control group, SAM significantly reduced viral loads in multiple tissues, including liver, spleen, lung, kidney, brain, and trachea, demonstrating its direct antiviral activity. Further analysis revealed that SAM modulated H9N2-induced inflammation by downregulating excessive innate immune responses. Specifically, SAM significantly enhanced the expression of antiviral effectors (OASL and MX-1) in the lungs during the early stages of viral infection, while attenuating the production of inflammatory cytokines (IL-6, IL-10) in the later stages. Additionally, SAM regulated the expression levels of pattern recognition receptors (MDA5, TLR3, and TLR7), thereby preventing excessive immune responses. These findings indicate that SAM possesses both antiviral and immunoregulatory effects, highlighting its potential as an effective anti-AIV agent for the management of H9N2 AIV infection.