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<p>Infectious hematopoietic necrosis (IHN) represents a significant threat to the rainbow trout aquaculture industry, and vaccination constitutes an effective strategy for prevention and control. To elucidate the immunoprotective efficacy of the recombinant IHNV-G protein vaccine in rainbow trout and its regulatory effects on intestinal mucosal immunity and microbiota composition, this study developed the vaccine and performed experimental evaluations using rainbow trout as a model organism. Following a 30-day immunization period, fish were challenged with 5.25 × 10⁶ PFU of IHNV. First, the immunoprotective efficacy of the vaccine was assessed through a challenge experiment. Subsequently, by integrating histopathological examination of intestinal tissues, detection of serum antibodies, analysis of intestinal immunity-related gene expression, and 16S rDNA sequencing of the gut microbiota, the impact of the vaccine on intestinal mucosal immunity and microbial composition was systematically investigated. The results demonstrate that the vaccine achieves a relative protection rate of 63%. Following immunization, serum antibody levels increase significantly, reaching a peak at 28 days post-vaccination. In the vaccine group, intestinal mucosal damage is significantly alleviated, and the structure of the intestinal villi is largely preserved. The expression of genes associated with intestinal immunity (e.g., <i>Muc2</i>, <i>IgT</i>, <i>CD4</i>, <i>MHC II</i>, <i>IFN-γ</i>, and <i>TNF-α</i>) is significantly upregulated. Following challenge, the vaccine group effectively mitigated the decline in intestinal microbial diversity. The abundance of beneficial bacterial taxa, such as Firmicutes and Bacteroidota, was significantly increased, whereas that of opportunistic pathogens, including Spirochaetota and <i>Brevinema</i>, was markedly suppressed (the abundance of <i>Brevinema</i> was only 0.01%, substantially lower than the 85.75% observed in the control group). The above results indicate that the recombinant IHNV-G protein vaccine significantly enhances resistance to IHNV in rainbow trout by stimulating systemic and mucosal immune responses, alleviating intestinal pathological damage, and modulating gut microbial composition. This finding provides an experimental foundation for the development of highly effective IHN vaccines targeting intestinal immunity and microecological regulation.</p>

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Effects of a recombinant IHNV glycoprotein vaccine on intestinal mucosal immunity and microbiota structure in rainbow trout (Oncorhynchus mykiss)

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • Yanyan Luo,
  • Jianfu Wang,
  • Yu Ning,
  • Hao Liu,
  • Zhiyuan Luo,
  • Jie Li,
  • Mingzhou Zhang,
  • Wenwen Zhang,
  • Lining Ren

摘要

Infectious hematopoietic necrosis (IHN) represents a significant threat to the rainbow trout aquaculture industry, and vaccination constitutes an effective strategy for prevention and control. To elucidate the immunoprotective efficacy of the recombinant IHNV-G protein vaccine in rainbow trout and its regulatory effects on intestinal mucosal immunity and microbiota composition, this study developed the vaccine and performed experimental evaluations using rainbow trout as a model organism. Following a 30-day immunization period, fish were challenged with 5.25 × 10⁶ PFU of IHNV. First, the immunoprotective efficacy of the vaccine was assessed through a challenge experiment. Subsequently, by integrating histopathological examination of intestinal tissues, detection of serum antibodies, analysis of intestinal immunity-related gene expression, and 16S rDNA sequencing of the gut microbiota, the impact of the vaccine on intestinal mucosal immunity and microbial composition was systematically investigated. The results demonstrate that the vaccine achieves a relative protection rate of 63%. Following immunization, serum antibody levels increase significantly, reaching a peak at 28 days post-vaccination. In the vaccine group, intestinal mucosal damage is significantly alleviated, and the structure of the intestinal villi is largely preserved. The expression of genes associated with intestinal immunity (e.g., Muc2, IgT, CD4, MHC II, IFN-γ, and TNF-α) is significantly upregulated. Following challenge, the vaccine group effectively mitigated the decline in intestinal microbial diversity. The abundance of beneficial bacterial taxa, such as Firmicutes and Bacteroidota, was significantly increased, whereas that of opportunistic pathogens, including Spirochaetota and Brevinema, was markedly suppressed (the abundance of Brevinema was only 0.01%, substantially lower than the 85.75% observed in the control group). The above results indicate that the recombinant IHNV-G protein vaccine significantly enhances resistance to IHNV in rainbow trout by stimulating systemic and mucosal immune responses, alleviating intestinal pathological damage, and modulating gut microbial composition. This finding provides an experimental foundation for the development of highly effective IHN vaccines targeting intestinal immunity and microecological regulation.