Human Cathelicidin, LL-37 a potential antiviral therapeutic for Rift Valley Fever Virus in Egypt.

Rift Valley Fever Virus (RVFV) is an arbovirus that circulates among animals and can be transmitted to humans. Mosquitoes are the primary vectors that allow RVFV to spread vertically and horizontally. Egypt was exposed to frequent outbreaks with devastating economic consequences. RVFV has a high incidence of worldwide dissemination and no specific vaccine or therapy. Linear Human Cathelicidin (LL-37), is a natural antimicrobial peptide with antiviral activity against numerous viruses. In addition to immunomodulatory effects, LL-37 directly influences viral encapsulation. This study aimed to evaluate the antiviral activity of LL-37 against RVFV in vitro. The post-entry and pre-incubation of LL-37 within Vero cells were assessed in the absence and presence of RVFV. LL-37 activity was assessed using a TCID50 endpoint test, qRT-PCR, and a western blot. When genomic RVFV was quantified, it resulted in a 48% direct inactivation of the viral envelope and a 36% reduction when the virus was pre-incubated with LL-37 before infection. LL-37 decreased viral infection by 75% and protected Vero cells against RVFV infection by 47% at a 1.25 µg/ml dosage. These findings imply that LL-37 exerts antiviral efficacy against RVFV by restricting virus entrance through direct disruption of the virus envelope and indirectly by triggering an immunological response. The effect of LL-37 is time-dependent. As a result, LL-37 may provide rapid and affordable therapies for RVFV infection in Egypt, both during outbreaks and as a preventive strategy.

Antiviral and protective effect of small interfering RNAs against rift valley fever virus in vitro.

BACKGROUND: Rift Valley Fever Virus (RVFV) is an arbovirus, a zoonotic disease that resurfaces as a potential hazard beyond geographic boundaries. Fever that can proceed to encephalitis, retinitis, hemorrhagic fever, and death is the main manifestation observed in human infections. RVFV has no authorized medication. The RNA interference (RNAi) gene silencing pathway is extremely well conserved. By targeting specific genes, small interfering RNA (siRNA) can be used to suppress viral replication. The aim of this study was to design specific siRNAs against RVFV and evaluate their prophylactic and antiviral effects on the Vero cells. METHODS AND RESULTS: Various siRNAs were designed using different bioinformatics tools. Three unique candidates were tested against an Egyptian sheep cell culture-adapted strain BSL-2 that suppressed RVFV N mRNA expression. SiRNAs were transfected a day before RVFV infection (pre-transfection), and 1 h after the viral infection (post-transfection), and were evaluated to detect the silencing activity and gene expression decrease using real-time PCR and a TCID50 endpoint test. The degree of N protein expression was determined by western blot 48 h after viral infection. D2 which targets the (488-506 nucleotides), the middle region of RVFV N mRNA was the most effective siRNA at 30 nM concentration, it almost eliminates N mRNA expression when utilized as antiviral or preventive therapy. siRNAs had a stronger antiviral silencing impact when they were post-transfected into Vero cells. CONCLUSION: Pre and post-transfection of siRNAs significantly reduced RVFV titer in cell lines, offering novel and potentially effective anti-RVFV epidemics and epizootics therapy.