Abstract:[Objectives] Ferritin exists widely in organisms, which can maintain a relatively stable iron content in cells and also participate in body’s immune response. In recent years, due to bacterial infection, the population of Rana amurensis has shown a downward trend. This study explores the expression pattern of ferritin H genes in bacteria-infected R. amurensis, hoping to provide a reference for the study of the mechanism of R. amurensis resistance to bacterial infection. [Methods] In this study, PCR was used to amplify the coding region of ferritin H(ferH) gene of R. amurensis and analyze its bioinformatics. Quantitative Real-time PCR (RT-qPCR) was used to detect the transcriptional changes of ferH gene in the liver, spleen, kidney, skin, and muscle tissue of R. amurensis after Aeromonas hydrophila (Ah) infection. The transcription level of ferHgene relative to the reference gene was calculated by 2﹣ΔΔCT using EXCEL 2019. Finally, immunofluorescence detection technology was used to analyze the expression of ferH protein of R. amurensis after Ah infection. Three positive regions were selected for each sample to take photos, and Image J software was used to analyze the relative average optical density. The above results were expressed as Mean ± SD. SPSS 26.0 was used for statistical analysis. One-way ANOVA was used to compare the difference between the treatment group and the control group, and the statistical significance was P < 0.05. GraphPad Prism 8 software was used for mapping. [Results] The results showed that the encoding region of ferHgene was 534 bp, encoding 177 amino acids (Fig. 1). The amino acid sequence analysis of this gene showed that it had the highest homology with R. temporaria, reaching 98.37% (Fig. 2). The results of RT-qPCR showed that ferHgene was widely transcribed in R. amurensis tissues (Fig. 3), and the transcription level of ferHgene was significantly up-regulated in liver, spleen, kidney, skin, and muscle tissues after Ah infection (P < 0.01). ferHgene in liver, skin and muscle tissues reached the peak of transcription 6 h after infection, which was 11.95, 24.31, and 24.72 times higher than that in the control group (P < 0.01). The peak transcription in spleen and kidney tissues was 18.22 and 18.19 times higher than that in the control group at 24 h after infection (P < 0.01) (Fig. 4). In addition, immunofluorescence assay results showed that the protein was expressed in the cytoplasm of the liver and muscle tissue of R. amurensis to varying degrees after infection with Ah. ferH protein expression was highest in liver and muscle tissue after Ah 6 h infection, 11.63 and 4.82 times higher than in control group, respectively (P < 0.01) (Fig. 5). [Conclusion] In conclusion, the ferHgene of R. amurensis is up-regulated in response to bacterial infection, suggesting that the gene is involved in bacterial immune response.