ABSTRACT
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-1ß) Q19A and R140A, which exhibited significantly increased in vivo biological activity compared with wild-type ChIL-1ß. 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-1ß, 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.
