IL-15基因对犬细小病毒VP2 DNA疫苗的免疫增强作用

IL-15 gene promotes immunogenic properties of VP2 DNA vaccine of canine parvovirus

为弄清犬白介素-15(cIL-15)能否增强犬细小病毒VP2DNA疫苗的免疫原性,本研究首先通过RT-PCR方法从犬脾脏淋巴细胞中扩增全长cIL-15cDNA基因,并构建其与Myc-His-tag融合和非融合的表达载体:pcDNA-cIL-15/MH和pcDNA-cIL-15。将pcDNA-cIL-15/MH载体转染HEK293T细胞,确定构建的表达载体能否介导cIL-15进行分泌表达。利用过去构建的VP2表达载体和pcDNA-cIL-15载体共免疫小鼠,用ELISA检测免疫后小鼠血清中的抗体滴度,并用MTT检测小鼠淋巴细胞的增殖活性和用ELISA测定淋巴细胞干扰素-γ和IL-4的表达。结果显示,构建的cIL-15表达载体能够介导cIL-15在真核细胞中的分泌表达。用VP2和cIL-15表达载体共免疫小鼠,抗体水平明显高于VP2载体单免疫组(P<0.01)。当免疫35d时,共免疫组淋巴细胞的刺激指数、干扰素-γ和IL-4的表达水平均明显高于VP2载体单免疫组(P<0.05)。结果表明,cIL-15可明显增强VP2DNA疫苗的免疫原性。

To investigate whether canine interleukin-15（cIL-15）gene enhances VP2 DNA vaccine immunogenicity of canine parvovirus（CPV）,the canine IL-15 cDNA was amplified from spleen lymphocytes by RT-PCR and its Myc/His-tag-fused（pcDNA-cIL-15/MH）and nonfused（pcDNA-cIL-15）vectors were constructed.The pcDNA-cIL-15/MH was transfected into HEK293 Tcells to determine whether cIL-15 vector can mediate cIL-15 expression in a secretory manner.The mice were immunized with VP2vector（pcDNA-CD5-VP2,constructed previously）,coimmunized with VP2 and cIL-15vectors（pcDNA-CD5-VP2 and pcDNA-cIL-15）and control vector（pcDNA3.1A）,respectively.The serum CPV-specific antibody levels in immunized mice were measured by ELISA;the lymphocyte stimulation indices were measured by MTT;and interferon-γ and IL-4 expressions of the lymphocytes were determined byELISA.The results showed that the constructed cIL-15 vector could mediate cIL-15 secretory expression in eukaryotic cells.Antibody levels in the sera of VP2/cIL-15vectors-coimmunized mice were significantly increased compared with VP2vector-immunized mice（P〈0.01）.The stimulation index,interferon-γand IL-4productions of splenic lymphocytes from VP2/cIL-15vectors-coimmunized mice were significantly higher（P〈0.05）than those from VP2vector-immunized mice at 35 dafter immunization.In conclusion,cIL-15 could significantly enhance VP2 DNA vaccine immunogenicity.