Endoplasmic reticulum: a focal point of Zika virus infection.

Zika virus (ZIKV) belongs to the Flavivirus genus of the Flaviviridae family. It is an arbovirus that can cause congenital abnormalities and is sexually transmissible. A series of outbreaks accompanied by unexpected severe clinical complications have captured medical attention to further characterize the clinical features of congenital ZIKV syndrome and its underlying pathophysiological mechanisms. Endoplasmic reticulum (ER) and ER-related proteins are essential in ZIKV genome replication. This review highlights the subcellular localization of ZIKV to the ER and ZIKV modulation on the architecture of the ER. This review also discusses ZIKV interaction with ER proteins such as signal peptidase complex subunit 1 (SPCS1), ER membrane complex (EMC) subunits, and ER translocon for viral replication. Furthermore, the review covers several important resulting effects of ZIKV infection to the ER and cellular processes including ER stress, reticulophagy, and paraptosis-like death. Pharmacological targeting of ZIKV-affected ER-resident proteins and ER-associated components demonstrate promising signs of combating ZIKV infection and rescuing host organisms from severe neurologic sequelae.

Carnosine exhibits significant antiviral activity against Dengue and Zika virus.

Dengue virus (DENV) and Zika virus (ZIKV) are flaviviruses transmitted to humans by their common vector, Aedes mosquitoes. DENV infection represents one of the most widely spread mosquito-borne diseases whereas ZIKV infection occasionally re-emerged in the past causing outbreaks. Although there have been considerable advances in understanding the pathophysiology of these viruses, no effective vaccines or antiviral drugs are currently available. In this study, we evaluated the antiviral activity of carnosine, an endogenous dipeptide (ß-alanyl-l-histidine), against DENV serotype 2 (DENV2) and ZIKV infection in human liver cells (Huh7). Computational studies were performed to predict the potential interactions between carnosine and viral proteins. Biochemical and cell-based assays were performed to validate the computational results. Mode-of-inhibition, plaque reduction, and immunostaining assays were performed to determine the antiviral activity of carnosine. Exogenous carnosine showed minimal cytotoxicity in Huh7 cells and rescued the viability of infected cells with EC50 values of 52.3 and 59.5 µM for DENV2 and ZIKV infection, respectively. Based on the mode-of-inhibition assays, carnosine inhibited DENV2 mainly by inhibiting viral genome replication and interfering with virus entry. Carnosine antiviral activity was verified with immunostaining assay where carnosine treatment diminished viral fluorescence signal. In conclusion, carnosine exhibited significant inhibitory effects against DENV2 and ZIKV replication in human liver cells and could be utilized as a lead peptide for the development of effective and safe antiviral agents against DENV and ZIKV.

Computational-aided design: minimal peptide sequence to block dengue virus transmission into cells.

Dengue virus (DV) infection is one of the main public health concerns, affecting approximately 390 million people worldwide, as reported by the World Health Organization. Yet, there is no antiviral treatment for DV infection. Therefore, the development of potent and nontoxic anti-DV, as a complement for the existing treatment strategies, is urgently needed. Herein, we investigate a series of small peptides inhibitors of DV antiviral activity targeting the entry process as the promising strategy to block DV infection. The peptides were designed based on our previously reported peptide sequence, DN58opt (TWWCFYFCRRHHPFWFFYRHN), to identify minimal effective inhibitory sequence through molecular docking and dynamics studies. The in silico designed peptides were synthesized using conventional Fmoc solid-phase peptide synthesis chemistry, purified by RP-HPLC and characterized using LCMS. Later, they were screened for their antiviral activity. One of the peptides, AC 001, was able to reduce about 40% of DV plaque formation. This observation correlates well with the molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) analysis - AC 001 showed the most favorable binding affinity through 60 ns simulations. Pairwise residue decomposition analysis has revealed four key residues that contributed to the binding of these peptides into the DV2 E protein pocket. This work identifies the minimal peptide sequence required to inhibit DV replication and explains the behavior observed on an atomic level using computational study.Communicated by Ramaswamy H. Sarma.