Hydroxychloroquine (HCQ) is an antimalarial drug also used in treating autoimmune diseases. Its antiviral activity was demonstrated in restricting HIV infection in vitro; however, the clinical implications remain controversial. Infection with dengue virus (DENV) is a global public health problem, and we lack an antiviral drug for DENV. Here, we evaluated the anti-DENV potential of treatment with HCQ. Immunofluorescence assays demonstrated that HCQ could inhibit DENV serotype 1–4 infection in vitro. RT-qPCR analysis of HCQ-treated cells showed induced expression of interferon (IFN)-related antiviral proteins and certain inflammatory cytokines. Mechanistic study suggested that HCQ activated the innate immune signaling pathways of IFN-β, AP-1, and NFκB. Knocking down mitochondrial antiviral signaling protein (MAVS), inhibiting TANK binding kinase 1 (TBK1)/inhibitor-κB kinase ɛ (IKKɛ), and blocking type I IFN receptor reduced the efficiency of HCQ against DENV-2 infection. Furthermore, HCQ significantly induced cellular production of reactive oxygen species (ROS), which was involved in the host defense system. Suppression of ROS production attenuated the innate immune activation and anti-DENV-2 effect of HCQ. In summary, HCQ triggers the host defense machinery by inducing ROS- and MAVS-mediated innate immune activation against DENV infection and may be a candidate drug for DENV infection.
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In our study, HCQ greatly inhibited viral replication in cells treated with HCQ before but not after DENV-2 infection. Thus, the cellular environment change with HCQ treatment may be crucial to restrict DENV-2 infection, whereas the late stage of interference in virion maturation might not be the major mechanism of HCQ anti-DENV-2 activity. Thus, HCQ preventive treatment in the area or season of a dengue pandemic might be a feasible strategy to reduce the severity and spread of DENV outbreak. Moreover, results from clinical trials showed that patients receiving HCQ combined with other antiviral drugs, hydroyurea and didanosine, showed significantly reduced HIV viral load and increased CD4 count (Paton and Aboulhab 2005). Therefore, combined therapy with HCQ and other antiviral drugs could be considered in DENV infection control. For example, an anti-DENV-2 iminosugar derivative (Wu and others 2002) may be used with HCQ to prevent DENV infection.
In conclusion, we demonstrated that HCQ could restrict DENV infection by activating ROS and a MAVS-mediated host IFN antiviral pathway. HCQ is a marketed drug that may be developed for clinical therapy of DENV infection.
