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

## TL;DR

A DNA vaccine followed by an inactivated vaccine boosts immune response in pigeons against Newcastle disease more effectively than either vaccine alone.

## Contribution

The study introduces a DNA prime-inactivated boost regimen that synergistically enhances immunogenicity against pigeon Newcastle disease.

## Key findings

- The DNA prime-inactivated boost regimen significantly increased antibody levels compared to either vaccine alone.
- Both DNA and inactivated vaccines alone induced good immune responses in pigeons.
- The combination regimen demonstrated a clear synergistic effect in hemagglutination inhibition antibody titers.

## Abstract

This study compares the immunogenicity of two vaccine platforms—DNA vaccine and inactivated vaccine—when used alone or in a prime–boost regimen for protecting pigeons against Newcastle disease. The DNA vaccine was engineered to express the viral fusion protein fused to chicken IL-18 as an immunostimulant, whereas the inactivated vaccine was prepared from a local virulent strain. Detailed preparation protocols for both vaccines are provided. Researchers tested four groups of pigeons: one received the DNA vaccine, one received the inactivated vaccine, one received both in a prime–boost strategy (DNA first, then inactivated), and one was a control group. Results showed that both vaccines alone induced good immune responses, but the combination of DNA prime and inactivated boost produced significantly higher antibody levels than either vaccine alone. The study emphasizes the combined strengths of both platforms and may provide a basis for future studies to improve vaccination strategies against pigeon Newcastle disease.

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.