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.