No abstract

Background: In recent decades RNAi has become a novel and effective tool to silence gene expression. The expression of shRNAs against target genes has now become a standard and powerful strategy for antiviral therapeutic approaches. Infectious bovine rhinotracheitis (IBR) is a domestic and wild ruminant viral disease that caused by bovine herpesvirus-1. Occasionally, its entry into the herd may cause vigorous economic damage due to losing weight, reduced output and limitation on livestock international trade. Vaccines against the disease are not fully effective and the need for an effective therapeutic approach is highly felt. In the present study an RNAi- based gene therapy was designed and implemented. Due to the essential role of UL25 gene for BHV-1 replication.Method: the sequence of UL25 gene was purposed for designing shRNA molecules. The UL25 gene sequence was extracted from the NCBI database and suitable shRNA molecules were purposed by using online soft wares. Three recombinant lentiviral vectors expressing short hairpin RNAs (shRNAs) versus the UL25 gene of IBRV were constructed and co-transfected into HEK 293T cells. The effectiveness of designed shRNA molecules was assayed by calculating TCID50 titers and observation of BHV-1 cytopathic effects. Results: The final calculations showed that all shRNAs had antiviral effects. In the TCID50 test, the shRNAs 1, 2 and 3 sufficiently decreased BHV1 output in comparison with the control groups (almost 98.22%, 99.63% and 99.54%, respectively than cells with IBRV inoculation and nearly 90.84%, 97.9% and 96.84%, respectively than cells with ORFV and scrambled vector inoculation). ShRNA-2 achieved maximal inhibition of viral replication. Conclusion: The results indicated that shRNAs targeting the UL25 gene showed considerable antiviral attributes and reduced IBRV multiplication in MDBK cells. In conclusion; RNA interference can be used as a gene therapy instrument against BHV-1 virus.