A DNA Prime-Inactivated Boost Regimen Enhances Immunogenicity Against Pigeon Newcastle Disease: A Comparative Study and Analysis of Synergistic Effects

Pigeon Newcastle disease poses a persistent threat to the global pigeon industry, underscoring the need for effective vaccination strategies. While both inactivated and DNA vaccines offer distinct advantages, the immunogenicity of a combined heterologous regimen remains underexplored. This study evaluated and compared three immunization strategies in pigeons: a DNA vaccine encoding the NDV F protein fused with chicken IL-18, an inactivated vaccine from a local virulent strain, and a DNA prime-inactivated boost regimen. The preparation workflows for both vaccine platforms are described in detail to provide methodological context for the immunological comparison. Critically, the prime–boost regimen elicited significantly higher hemagglutination inhibition (HI) antibody titers than either vaccine administered alone, demonstrating a clear synergistic effect. These findings highlight the complementary roles of the two platforms and provide a strong immunological rationale for further evaluation of this sequential strategy. Future studies incorporating viral challenge experiments and long-term immune monitoring are needed to determine whether the enhanced HI antibody response translates into protective efficacy under field conditions.