Novel Ionophores Active against La Crosse Virus Identified through Rapid Antiviral Screening

Abstract

Bunyaviruses are significant human pathogens, causing diseases ranging from hemorrhagic fevers to encephalitis. Among these viruses, La Crosse virus (LACV), a member of the California serogroup, circulates in the eastern and midwestern United States. While LACV infection is often asymptomatic, dozens of cases of encephalitis are reported yearly. Unfortunately, no antivirals have been approved to treat LACV infection. Here, we developed a method to rapidly test potential antivirals against LACV infection. From this screen, we identified several potential antiviral molecules, including known antivirals. Additionally, we identified many novel antivirals that exhibited antiviral activity without affecting cellular viability. Valinomycin, a potassium ionophore, was among our top targets. We found that valinomycin exhibited potent anti-LACV activity in multiple cell types in a dose-dependent manner. Valinomycin did not affect particle stability or infectivity, suggesting that it may preclude virus replication by altering cellular potassium ions, a known determinant of LACV entry. We extended these results to other ionophores and found that the antiviral activity of valinomycin extended to other viral families, including bunyaviruses (Rift Valley fever virus, Keystone virus), enteroviruses (coxsackievirus, rhinovirus), flavirivuses (Zika virus), and coronaviruses (human coronavirus 229E [HCoV-229E] and Middle East respiratory syndrome CoV [MERS-CoV]). In all viral infections, we observed significant reductions in virus titer in valinomycin-treated cells. In sum, we demonstrate the importance of potassium ions to virus infection, suggesting a potential therapeutic target to disrupt virus replication.

Valinomycin as a potential antiviral agent against coronaviruses: A review

“…At the same time, National Institute for Viral Disease Control and Prevention, China CDC, Beijing, China, also revealed that VAL inhibited the replication of MERS-CoV with an EC 50 value of 6.07 μM and CC 50 value of 5.88 μM using an experimental design of dose–response studies in vitro [ 70 ]. Recently, it demonstrated that VAL exhibited inhibitory activity with an IC 50 value of 0.005 μM [ 71 ].…”

“…During the rapid antiviral screening to identify potential antivirals against the La Crosse virus, the VAL active against HCoV-229E infection was reported by Sandler et al. [ 71 ]. VAL showed inhibitory activity with an IC 50 value of 0.067 μM and exhibited a potent inhibitory against the replication of HCoV-229E at the concentration of 10 μM.…”

“…Sandler et al. demonstrated that VAL exhibited inhibitory activity against CVB3 and HRV2 during culture tests on Huh7 cells with IC 50 values of 0.971 μM and 0.61 μM, respectively [ 71 ].…”

“…Sandler et al. established a rapid antiviral screening method to screen several potential antiviral molecules, including known and novel antivirals, which exhibited antiviral activity against LACV [ 71 ]. According to Mankouri et al.…”

“…reported that VAL does not reduce viral particle infectivity and the ability of virus binding to host cells, but may preclude virus replication by altering cellular K + gradient. In other words, VAL exerted antiviral activity at the entry stages of bunyaviruses infection within host cells [ 71 ]. VAL potently inhibited LACV replication with an IC 50 value of 0.588 μM and 0.898 μM during culture tests on Huh7 cells and Vero-E6 cells, respectively.…”