Salmonella Enteritidis (SE) is a highly adapted pathogen causing severe economic losses in the poultry industry worldwide. Chickens infected by SE are a major source of human food poisoning. Vaccination is an effective approach to control SE infections. This study evaluated the immunogenicity and protective efficacy of a SE sptP deletion mutant (C50336ΔsptP) as a live attenuated vaccine (LAV) candidate in chickens. 14 day-old specific pathogen-free (SPF) chickens were intramuscularly immunized with various doses of C50336ΔsptP. Several groups of chickens were challenged with the virulent wild-type SE strain Z-11 via the same route at 14 days post vaccination. Compared to the control group, the groups vaccinated with 1 × 10⁶, 1 × 10⁷ and 1 × 10⁸ colony-forming units (CFU) of C50336ΔsptP exhibited no clinical symptoms after immunization. Only slight pathological changes occurred in the organs of the 1 × 10⁹ CFU vaccinated group. C50336ΔsptP bacteria were cleared from the organs of immunized chickens within 14 days after vaccination. Lymphocyte proliferation and serum cytokine analyses indicated that significant cellular immune responses were induced after the vaccination of C50336ΔsptP. Compared to the control group, specific IgG antibody levels increased significantly in vaccinated chickens, and the levels increased markedly after the challenge. The 1 × 10⁷, 1 × 10⁸, and 1 × 10⁹ CFU vaccinated chickens groups showed no clinical symptoms or pathological changes, and no death after the lethal challenge. Whereas severe clinical signs of disease and pathological changes were observed in the control group chickens after the challenge. These results suggest that a single dose of C50336ΔsptP could be an effective LAV candidate to against SE infection in chickens.

肠炎沙门氏菌（SE）是高度适应的病原体，在全世界的家禽业中造成严重的经济损失。被SE感染的鸡是人类食物中毒的主要来源。接种疫苗是控制SE感染的有效方法。这项研究评估了SE sptP缺失突变体（C50336ΔsptP）作为鸡减毒活疫苗（LAV）候选者的免疫原性和保护功效。14天老无特定病原（SPF）鸡肌内用不同剂量C50336Δ的免疫SPTP。疫苗接种后第14天，几组鸡通过相同途径用有毒力的野生型SE株Z-11攻击。与对照组相比，接种了1×10 ⁶疫苗的组，1×10 ⁷和1×10 ⁸ C50336Δ的菌落形成单位（CFU）SPTP表现出免疫后没有临床症状。1×10 ⁹ CFU疫苗接种组的器官仅发生了轻微的病理变化。C50336Δ SPTP细菌从免疫鸡的器官在接种后14天清除。淋巴细胞增殖和细胞因子的血清分析表明显著细胞免疫应答C50336Δ的疫苗接种后诱导的SPTP。与对照组相比，接种疫苗的鸡的特异性IgG抗体水平显着增加，并且在攻击后显着增加。1×10 ^7，1 ×10⁸和1×10 ⁹ CFU疫苗接种的鸡组未显示任何临床症状或病理变化，并且在致死性攻击后也没有死亡。攻击后对照组鸡中观察到严重的疾病和病理变化的临床症状。这些结果表明，C50336Δ单剂量SPTP可能是一种有效的LAV候选人对SE感染鸡。