China Animal Husbandry and Veterinary Medicine ›› 2023, Vol. 50 ›› Issue (1): 26-36.doi: 10.16431/j.cnki.1671-7236.2023.01.003

• Biotechnology • Previous Articles     Next Articles

Construction of Deletion Strain of Brucella BPE159 Gene and Effect of BPE159 Protein on Expression of Cellular Autophagy Factors

WEI Chunyan1, GUO Jia1, ZHU Dexin1, ZHANG Wei1, ZHU Jiale1, DEN Xingmei1, JIA Sifeng2, LIU Liangbo1, ZHANG Hui1   

  1. 1. Key Laboratory of Prevention and Control of Animal Disease, Xinjiang Production & Construction Corps, College of Animal Science and Technology, Shihezi University, Shihezi 832000, China;
    2. Qilu Animal Health Products Company, Jinan 250100, China
  • Received:2022-08-05 Online:2023-01-05 Published:2023-01-04

Abstract: 【Objective】 This study was aimed to construct Brucella BPE159 gene deletion strain, and study the in vitro growth characteristics and survival ability of the deletion strains in host cells and explore the effect of the secreted protein BPE159 on autophagy factor expression during Brucella infection.【Method】 The recombinant plasmid of Brucella BPE159 gene was constructed by homologous recombination.The Brucella BPE159 gene deletion strain S2308ΔBPE159 was constructed by electrotransformation of recombinant plasmid into Brucella S2308 competent cells.Specific primers were used to amplify the BPE159 gene, ligated and transformed to construct the pBBR1MCS-4-BPE159 vector, and the plasmid was extracted and electroporated to construct the BPE159 gene complement strain S2308ΔBPE159-C.Genetic stability of deletion and complement strains was determined by agarose gel electrophoresis.The Brucella-infected mouse macrophage RAW264.7 model was constructed, and the expression levels of autophagy cytokines ATG5, Beclin1, LC3a and LC3b genes after Brucella infection were detected by Real-time PCR.Mouse macrophages were infected with S2308, S2308ΔBPE159 and S2308ΔBPE159-C strains, and total RNA was collected.The effect of BPE159 gene deletion on the expression levels of autophagy cytokines after Brucella infection was detected by Real-time PCR.S2308, S2308ΔBPE159 and S2308ΔBPE159-C strains were cultured at the same initial concentration, and the trend of growth changes was observed, and the survival and reproduction ability of S2308ΔBPE159 at different time points was evaluated.【Result】 The BPE159 gene deletion strain S2308ΔBPE159 and the complement strain S2308ΔBPE159-C were successfully constructed, and they were stably inherited for 10 generations.The results of Real-time PCR showed that after 24 h infection of Brucella, compared with PBS, autophagy factor ATG5 gene was significantly decreased (P<0.05), Beclin1, LC3a and LC3b genes were extremely significantly decreased (P<0.01).Compared with S2308 group, the expression levels of autophagic factors Beclin1 and LC3a genes were significantly increased (P<0.05), and the expression levels of ATG5 and LC3b genes were extremely significantly increased (P<0.01) in S2308ΔBPE159 group.The growth curve results showed that, under the same culture conditions, S2308ΔBPE159 and S2308ΔBPE159-C had similar growth trends to S2308.The results of intracellular survival showed that, 8 h after infection, the number of S2308ΔBPE159 in cells was extremely significantly lower than that of parental strain S2308 (P<0.01), and the viability at 12 and 24 h was significantly lower than that of S2308 (P<0.05).【Conclusion】 In this study, we successfully constructed and obtained BPE159 gene deletion strain and complement strain of Brucella with good genetic stability.S2308ΔBPE159 had a similar growth trend as S2308, but its viability and reproduction ability was obviously reduced.After BPE159 gene deletion, Brucella could promote the expression of autophagic factors.The results of this study laid a foundation for studying the biological function and regulatory mechanism of secreted proteins of Brucella.

Key words: Brucella; BPE159 gene; gene deletion; autophagy

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