Combination Regimens of Favipiravir Plus Interferon Alpha Inhibit Chikungunya Virus Replication in Clinically Relevant Human Cell Lines

Abstract

Chikungunya virus (CHIKV) is an alphavirus associated with a broad tissue tropism for which no antivirals or vaccines are approved. This study evaluated the antiviral potential of favipiravir (FAV), interferon-alpha (IFN), and ribavirin (RBV) against CHIKV as mono- and combination-therapy in cell lines that are clinically relevant to human infection. Cells derived from human connective tissue (HT-1080), neurons (SK-N-MC), and skin (HFF-1) were infected with CHIKV and treated with different concentrations of FAV, IFN, or RBV. Viral supernatant was sampled daily and the burden was quantified by plaque assay on Vero cells. FAV and IFN were the most effective against CHIKV on various cell lines, suppressing the viral burden at clinically achievable concentrations; although the degree of antiviral activity was heavily influenced by cell type. RBV was not effective and demonstrated substantial toxicity, indicating that it is not a feasible candidate for CHIKV. The combination of FAV and IFN was then assessed on all cell lines. Combination therapy enhanced antiviral activity in HT-1080 and SK-N-MC cells, but not in HFF-1 cells. We developed a pharmacokinetic/pharmacodynamic model that described the viral burden and inhibitory antiviral effect. Simulations from this model predicted clinically relevant concentrations of FAV plus IFN completely suppressed CHIKV replication in HT-1080 cells, and considerably slowed down the rate of viral replication in SK-N-MC cells. The model predicted substantial inhibition of viral replication by clinical IFN regimens in HFF-1 cells. Our results highlight the antiviral potential of FAV and IFN combination regimens against CHIKV in clinically relevant cell types.

Combination Therapy with UV-4B and Molnupiravir Enhances SARS-CoV-2 Suppression

“…First, we believed that evaluations of the EIDD-1931 antiviral effect would be most generalizable to humans if preclinical evaluations were carried out using human-derived tissues. Our previous work with nucleoside analogues has shown that antiviral activity for these agents is heavily influenced by the cell type selected for antiviral evaluations, specifically the tissue and species from which the cells are derived [ 52 , 53 ]. This specific activity is most likely due to differences in drug uptake and metabolism into the active triphosphate form, as phosphorylation kinetics of nucleoside polymerase inhibitors vary between cell types [ 52 , 53 , 54 , 55 ].…”

“…Our previous work with nucleoside analogues has shown that antiviral activity for these agents is heavily influenced by the cell type selected for antiviral evaluations, specifically the tissue and species from which the cells are derived [ 52 , 53 ]. This specific activity is most likely due to differences in drug uptake and metabolism into the active triphosphate form, as phosphorylation kinetics of nucleoside polymerase inhibitors vary between cell types [ 52 , 53 , 54 , 55 ]. Second, in vitro evaluations of combination therapy are an ideal first step in both identifying and narrowing down to the most promising combinations and exposures of each drug in the combination prior to animal experimentation.…”

Antiviral Evaluation of UV-4B and Interferon-Alpha Combination Regimens against Dengue Virus

“…Since FAV is administered as a prodrug whose effectiveness is linked to efficient drug uptake and activation by the host cell, it is possible tissue dependent variability in these processes impacted drug effect. These considerations explain the absence of activity in HFF-1 cells, as work done in our laboratory evaluating intracellular concentrations of FAV and FAV-RTP demonstrate FAV does not effectively penetrate HFF-1 cell membranes [ 30 ], but they do not adequately explain lack of effect in HUH-7 and SK-N-MC cells. Studies investigating FAV’s antiviral potential against Zika virus (ZIKV) conducted in our lab have shown robust inhibition of ZIKV in both cell lines [ 21 ] indicating FAV uptake and activation is efficient in these cells.…”

“…Previous anti-DENV assays with the above-mentioned agents were conducted using Vero cells, which are often considered to be the gold standard for viral research due to their high permissivity to viral infection. Vero cells, however, are derived from the kidneys of non-human primates and may not reflect the antiviral effect that would be achieved in man, as we have previously shown that viral susceptibility to antiviral therapy is highly variable based on the host cell line employed for the investigations [ 29 , 30 ]. Here, we evaluated the antiviral candidates against DENV in multiple cell lines derived from human tissue in an attempt to maximize translation to man.…”

Understanding the Biology and Immune Pathogenesis of Chikungunya Virus Infection for Diagnostic and Vaccine Development

“…It has been shown that CHIKV infection triggers the induction of type I IFNs (IFN-α and IFN-β) and IFN-γ [ 74 , 77 ]. In several cell lines infected with CHIKV, including Vero, HFF-1, HT-1080, and SK-N-MC cell lines, IFN-α dose-dependently inhibited CHIKV replication [ 78 , 79 ]. However, although IFN-α and IFN-β share an identical receptor, they have distinct mechanisms for protecting against severe CHIKV diseases [ 73 ].…”