Inhibition Of HBsAg Gene Expression By Plant-derived SiRNAs

Small interference RNAs(siRNAs)and microRNAs(miRNAs)are the two major small RNAs,which silence gene expression by mRNA destabilization and translational repression.These samll RNAs participate in a variety of biological processes including growth and development,cell proliferation and differentiation,cell apoptosis and stress response et al.Previously studies from our group made the discovery that some plant miRNAs derived from food or herbs accumulate in the serum of humans and regulate mammalian or influenza virus gene expression in a sequence-specific manner.Although the exact mechanims of how exogenous miRNAs are shutted into the mammalian cells are still unclear,these findings raise an appealing possiblity that food-derived miRNAs may offer a new stratagy to deliver small silencing RNAs as therapeutics to our bodies.In this study,we set up a plant-engineering system to express the potentially therapeutical articicial microRNA(amiRNA)sequences employing plant intrinsic miRNA biogenesis machinary.The detailed analyses showed two piece of siRNA sequences target to Hepatitis B Virus(HBV)surface antigene gene(HBsAg),named amiR516 and amiR467,are successfully generated in the plant.Feeding with the amiR516 or amiR467,the expression of HBsAg in the transgenic mouses is significantly downregulated.Moreover,the relieved liver lesion and autoimmunosuppression due to the persistent expression of HBsAg are observed.In summary,we successfully expressed the therapeutical siRNA sequences in the plant and proved they are functional to silence target genes.This work not only provide a new drug developmental method for HBV treatment treatment but also lay a strong foundation to build a plant engineering platform to produce safe and clinical gene therapy drugs.