胸腺五肽和法氏囊活性五肽的融合表达及其对禽流感灭活疫苗的佐剂效应

Expression and adjuvant effects of the fusion peptide TBP5

摘要:

胸腺五肽 (Thymopentin，TP5) 和法氏囊活性五肽 (Bursopentin，BP5) 均具有重要的免疫学功能，但二者在基因水平上的联合应用尚未见报道。为研究TP5和BP5形成的重组融合肽TP5-BP5 (TBP5) 是否具有免疫佐剂活性，根据大肠杆菌偏嗜密码子设计并合成重组融合肽TBP5编码序列，将其克隆至pET-32a表达载体中，重组表达载体在大肠杆菌BL21中诱导表达，并采用MTT法检测其表达产物的体外活性。同时以TBP5联合H9N2型禽流感病毒 (Avian influenza virus，AIV) 灭活疫苗免疫小鼠，检测免疫后小鼠的HI抗体、HA抗体效价和细胞因子 (IL-4和IFN-γ) 的分泌水平，并通过动物免疫保护试验来评价其对小鼠的免疫保护作用。结果显示，TBP5在大肠杆菌中获得表达；TBP5能显著促进小鼠胸腺T淋巴细胞和脾脏B淋巴细胞的增殖，并能增强机体免疫后HI抗体和HA抗体效价、提高细胞因子IL-4和IFN-γ的分泌水平，表明TBP5既能增强机体体液免疫应答，又能增强细胞免疫应答。动物免疫保护试验结果显示TBP5有助于小鼠肺脏中H9N2型AIV病毒的清除。结果表明，重组融合肽TBP5具有良好的免疫佐剂的潜能，为进一步研究开发新型疫苗佐剂奠定了基础。

Abstract:

Thymopentin (TP5) and bursopentin (BP5) are both immunopotentiators. To explore whether the TP5-BP5 fusion peptide (TBP5) has adjuvant activity or not, we cloned the TBP5 gene and confirmed that the TBP5 gene in a recombinant prokaryotic expression plasmid was successfully expressed in Escherichia coli BL21. TBP5 significantly promoted the proliferation of thymic and splenic lymphocytes of mice. The potential adjuvant activity of the TBP5 was examined in mice by coinjecting TBP5 and H9N2 avian influenza virus (AIV) inactivated vaccine. HI antibody titers, HA antibodies and cytokines levels (IL-4 and IFN-γ) were determined. We found that TBP5 markedly elevated serum HI titers and HA antibody levels, induced the secretion of both IL-4 and IFN-γ cytokines. Furthermore, virus challenge experiments confirmed that TBP5 contributed to inhibition replication of the virus [H9N2 AIV (A/chicken/Jiangsu/NJ07/05)] from mouse lungs. Altogether, these findings suggest that TBP5 may be an effective adjuvant for avian vaccine and that this study provides a reference for further research on new vaccine adjuvants.