Inhibitory effects of shRNAs targeting genes encoding viral capsomeres VP1-VP4 on EV71 replication

Abstract

Objective To evaluate the inhibitory effects of shRNAs targeting genes encoding viral capsomeres VP1-VP4 on enterovirus 71 (EV71) replication when used alone or in combination.Methods Short hairpin RNAs (shRNAs) targeting genes encoding VP1-VP4 protein of EV71 were designed and then respectively inserted into lentiviral vector pLKD-CMV-GFP-U6 to construct the recombinant plasmids.The expression plasmids together with psPAX2 and pMD2.G were transfected into 293T cells to induce the expression of recombinant lentiviruses,which were collected on the third day after transfection.The titers of recombined lentiviruses were determined by real-time PCR.The effects of shRNAs used alone or in combination on the expression of EV71 at mRNA and protein levels were respectively detected by real-time PCR and Western blot.Results The inhibitory effects of shRNAs on EV71 replication showed no significant differences among various strains (isolated from fatal cases,severe cases,mild cases and FY0805) (P＞0.05).Their inhibition rates were 51.6％ (sh-VP1-1),85.1％ (sh-VP1-2),76.4％ (sh-VP1-3),57.5％ (sh-VP2-1),81.4％ (sh-VP2-2),79.5％ (sh-VP2-3),68.9％ (sh-VP3) and 56.7％ (sh-VP4) respectively,and they were in a dosage dependent manner.sh-VP1-2 in combination with sh-VP2-2 showed the highest inhibition rate reaching up to 96.6％.Moreover,shRNAs used in combination showed better effects than any one used alone even at double dosage.Conclusion All shRNAs targeting viral capsid VP1-VP4 genes showed inhibitory effects on EV71 replication with inhibition rates over 50％ and the effects could be strengthened when using shRNAs in combination. Key words: Lentivirus; Gene targeting; Hand-foot-and-mouth disease; EV71