[Objective]We studied the inhibition of infectious bursal disease virus ( IBDV ) replication in chicken embryos by recombinant avian adeno-associated virus (AAAV)-delivered VP1- and VP2-specific microRNAs (miRNAs).[Methods and Results]We co-transfected AAV-293 cells with the VP1- or VP2 gene-specific miRNA expression vector pAITR-RFPmiVP1 or AITR-RFPmiVP2E, AAAV packaging vector pcDNA-ARC and adenovirus helper vector pHelper, resulting in recombinant virus rAAAV-RFPmiVP1 or rAAAV-RFPmiVP2E.We also generated the recombinant viruses rAAAV-RFP (without miRNA expression cassette) and rAAAV-RFPmiVP2con ( expressing control miRNA ) using the same method as the control purpose.Electron microscopy showed that the recombinant viruses had a typical morphology of AAV.We confirmed the presence of miRNA expression cassette in the recombinant viral genomes by using PCR.Our poly (A)-tailed RT-PCR showed correct expression of the miRNAs in the rAAAV-transduced DF-1 cells.We inoculated the recombinant viruses individually into 8-day-old SPF chicken embryos and then challenged them using Lukert strain IBDV on day 2 after inoculation.Our IBDV titration assay showed that the 50％ tissue culture infectious dose ( TCID50) of rAAAV-RFP- or rAAAV-RFPmiVP2con-inoculated group was 8.0 log10, whereas the TCID50 of rAAAV-RFPmiVP1-inoculated group decreased to 1.0 and 0.8 log10 on day 3 and 6 after challenge, respectively.Similarly, the TCID50 of rAAAV-RFPmiVP2E-inoculated group decreased to 1.5 and 2.0 log10, respectively.[Conclusion]These data suggest that rAAAV can transduce efficiently chicken embryos and the expressed VP1- and VP2-specific miRNAs can inhibit the replication of IBDV efficiently.%[目的]在鸡胚水平上探索VP1和VP2基因特异miRNA抑制传染性法氏囊病病毒(infectious bursaldisease virus,IBDV)复制的可行性.[方法与结果]将表达VP1基因特异miRNA重组载体pAITR-RFPmiVP1或VP2基因特异miRNA重组载体pAITR-RFPmiVP2E与禽腺联病毒(avian adeno-associated virus,AAAV)包装载体pcDNA-ARC和腺病毒辅助载体pHelper共转染AAV-293细胞,获得重组病毒rAAAV-RFPmiVP1和rAAAV-RFPmiVP2E,用同样方法获得不表达miRNA的rAAAV-RFP和表达对照miRNA的rAAAV-RFPmiVP2con.电镜观察显示重组病毒具有典型的AAAV颗粒形态;PCR检测结果表明其基因组中含miRNA表达盒;经poly(A)加尾RT-PCR检测证明重组病毒感染细胞能表达基因特异的miRNA.分别将重组病毒经卵黄囊途径接种8日龄SPF鸡胚,然后经绒毛尿囊膜途径用Lukert株IBDV攻毒,收获鸡胚进行IBDV组织细胞半数感染剂量(TCID<,50>)测定.结果在攻毒后第3天,rAAAV-RFP和rAAAV-RFPmiVP2con接种组的IBDV TCID<,50>为8.0 log10,rAAAV-RFPmiVP1和rAAAV-RFPmiVP2E接种组的IBDV TCID<,50>分别下降到1.0和1.5 log10;在攻毒后第6天,rAAAV-RFP和rAAAV-RFPmiVP2con接种组的IBDV TCID<,50>仍为8.0 log10,rAAAV-RFPmiVP1和rAAAV-RFPmiVP2E接种组的TCID<,50>分别下降到0.8和2.0 log10.[结论]rAAAV是有效的miRNA鸡胚导入载体,表达的VP1和VP2基因特异miRNA能有效阻断IBDV复制.
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