*Corresponding author: asoebandrio@gmail.com

This study aimed to analyze the efficacy of NanB sialidase from Pasteurella multocida in suppressing Influenza A H9N2 infection both in vitro and in vivo. NanB sialidase experiments for viral suppression were carried out in vitro on MDCK cells at dosages of 0, 32, 64, 129, and 258 mU/mL. On the other hand, 14-day-old commercial laying hens were split up into five groups for the in vivo test: virus control (KV), negative control (KNV), and groups that received sialidase once (P1), twice (P2), and three times (P3) on various days at a concentration of 129 mU/mL intranasally. After the H9N2 virus was administered to groups KV, P1, P2, and P3 on day 4, the blood samples were collected to measure antibody titters against the virus. Clinical symptoms, body weight, antibody titters, the amount of viral replication in the lungs, and Toll-like receptor gene expression were all observed after the infection. NanB sialidase has proven effective in inhibiting H9N2 viruses, with an optimal dose of 129 mU/mL in vitro. P3, which was administered once daily for three consecutive days, was the group that performed best in terms of NanB sialidase's ability to inhibit AI H9N2 virus infection. The anti-avian influenza efficacy of NanB sialidase was also seen from its effect on TLR7 expression in the P3 treatment group, which was not significantly different compared to the KNV group. The results indicated that NanB sialidase, with the appropriate dosage and frequency, can effectively suppress avian influenza virus infection.

To Cite This Article: Putra MA, Poetri ON, Wibawan WT, Indrawati A, Silaen OSM, Kurnia RS, Nugroho CMH, Krisnamurti DGB and Soebandrio A, 2025. the efficacy of bacterial sialidase Pasteurella multocida against influenza a subtype H9N2 virus in-vitro and in-vivo. Pak Vet J. http://dx.doi.org/10.29261/pakvetj/2025.285