Chicken interleukin-1β mutants are effective single-dose vaccine adjuvants that enhance mucosal immune response

The use of cytokines as adjuvants in poultry is promising because they may enhance immune responses to antigens. In this study, we created two mutants, chicken interleukin-1 beta (ChIL-1β) Q19A and R140A, which exhibited significantly increased in vivo biological activity compared with wild-type ChIL-1β. The potential mucosal adjuvant activity of the mutants Q19A and R140A was evaluated in chickens through the intranasal coadministration of a single dose of the Newcastle disease virus (NDV) vaccine with Q19A or R140A. Compared with chickens vaccinated with only the NDV vaccine or the NDV vaccine plus wild-type recombinant ChIL-1β, chickens vaccinated with Q19A or R140A had significantly increased serum hemagglutination-inhibition antibody titers and anti-NDV-specific IgA antibody levels 1 week later, a high amount of interferon-γ secretion from splenocytes, and increased secretory IgA accumulated in nasal tissues. In addition, molecular dynamics simulations of the mutant R140A bound to its receptor (IL-1RI) and receptor accessory protein (IL-1RAcP) were more energetically favorable than the analogous wild-type ternary complex resulting in a decreased energy, which may stabilize the R140A/IL-1RI/IL-1RAcP complex. In conclusion, the mutants Q19A and R140A are effective adjuvants that accelerate and enhance chicken mucosal immunity when co-administered with one dose of the NDV vaccine.