Mechanism of enhancement of the antiviral action of interferon against herpes simplex virus-1 by chloroquine

COVID-19 Pandemic: Outbreak, Potential Vaccines And Medications

The outbreak of the current global pandemic caused by the spread of a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed an unprecedented threat to global health and economy across the whole world. As of today, the number of cases diagnosed with SARS-CoV-2 is exceeding 271 million with over 5.32 million deaths globally. Despite the high throughput technology and considerable advances in sciences, the outbreaks of the COVID-19 pandemic present a colossal challenge to scientific community. Scientists and clinicians all over the world are putting tremendous efforts to develop effective treatments to combat this deadly pathogen, at least to contain it momentarily until an adequate treatment regimen is available. Conventionally, vaccines have been developed as one of the therapeutic strategies to restrict infectious diseases. Although several vaccines are in the pipeline, evaluation of efficacy in animals’ studies and human are time-consuming. On the other hand, several drugs already in clinical use are being employed to test their efficacy against SARS-CoV-2. Some of these drugs have been already used as anti-viral drugs and others have been used for different therapeutic purposes. In this review, we summarize the ongoing efforts to control the dissemination of SARS-CoV-2 and highlight the potential prophylactic and therapeutic measures including the recently developed vaccines in the foreseeable future. Moreover, we emphasize an importance of having a customized strategy that can be easily and quickly employed to overcome possible future outbreaks.

Broad spectrum anti-coronavirus activity of a series of anti-malaria quinoline analogues

In this study, a series of 10 quinoline analogues was evaluated for their in vitro antiviral activity against a panel of alpha- and beta-coronaviruses, including the severe acute respiratory syndrome coronaviruses 1 and 2 (SARS-CoV-1 and SARS-CoV-2), as well as the human coronaviruses (HCoV) 229E and OC43. Chloroquine and hydroxychloroquine were the most potent with antiviral EC₅₀ values in the range of 0.12-12 μM. Chloroquine displayed the most favorable selectivity index (i.e. ratio cytotoxic versus antiviral concentration), being 165 for HCoV-OC43 in HEL cells. Potent anti-coronavirus activity was also observed with amodiaquine, ferroquine and mefloquine, although this was associated with substantial cytotoxicity for mefloquine. Primaquine, quinidine, quinine and tafenoquine only blocked coronavirus replication at higher concentrations, while piperaquine completely lacked antiviral and cytotoxic effects. A time-of-addition experiment in HCoV-229E-infected HEL cells revealed that chloroquine interferes with viral entry at a post-attachment stage. Using confocal microscopy, no viral RNA synthesis could be detected upon treatment of SARS-CoV-2-infected cells with chloroquine. The inhibition of SARS-CoV-2 replication by chloroquine and hydroxychloroquine coincided with an inhibitory effect on the autophagy pathway as visualized by a dose-dependent increase in LC3-positive puncta. The latter effect was less pronounced or even absent with the other quinolines. In summary, we showed that several quinoline analogues, including chloroquine, hydroxychloroquine, amodiaquine, ferroquine and mefloquine, exhibit broad anti-coronavirus activity in vitro.

Chloroquine commonly induces hormetic dose responses

The use of chloroquine in the treatment of COVID-19 has received considerable attention. The recent intense focus on this application of chloroquine stimulated an investigation into the effects of chloroquine at low doses on highly biologically-diverse models and whether it may induce hormetic-biphasic dose response effects. The assessment revealed that hormetic effects have been commonly induced by chloroquine, affecting numerous cell types, including tumor cell lines (e.g. human breast and colon) and non-tumor cell lines, enhancing viral replication, sperm motility, various behavioral endpoints as well as decreasing risks of convulsions, and enhancing a spectrum of neuroprotective responses within a preconditioning experimental framework. These diverse and complex findings indicate that hormetic dose responses commonly occur with chloroquine treatment with a range of biological models and endpoints. These findings have implications concerning study design features including the number and spacing of doses, and suggest a range of possible clinical concerns and opportunities depending on the endpoint considered.

Antimalarials as Antivirals for COVID-19: Believe it or Not!

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus responsible for the coronavirus disease -19 (COVID-19). Since December 2019, SARS-CoV-2 has infected millions of people worldwide, leaving hundreds of thousands dead. Chloroquine (CQ) and Hydroxychloroquine (HCQ) are antimalarial medications that have been found to have in vitro efficacy against SARS-CoV-2. Several small prospective studies have shown positive outcomes. However, this result has not been universal, and concerns have been raised regarding the indiscriminate use and potential side effects. The clinicians are conflicted regarding the usage of these medications. Appropriate dose and duration of therapy are unknown. Here, we will discuss the pharmacokinetic and pharmacodynamic properties of CQ and HCQ, as well as review the antiviral properties. The manuscript will also examine the available data from recent clinical and preclinical trials in order to shed light on the apparent inconsistencies.

Improving Encapsulation of Hydrophilic Chloroquine Diphosphate into Biodegradable Nanoparticles: A Promising Approach against Herpes Virus Simplex-1 Infection

Chloroquine diphosphate (CQ) is a hydrophilic drug with low entrapment efficiency in hydrophobic nanoparticles (NP). Herpes simplex virus type 1 (HSV-1) is an enveloped double-stranded DNA virus worldwide known as a common human pathogen. This study aims to develop chloroquine-loaded poly(lactic acid) (PLA) nanoparticles (CQ-NP) to improve the chloroquine anti- HSV-1 efficacy. CQ-NP were successfully prepared using a modified emulsification-solvent evaporation method. Physicochemical properties of the NP were monitored using dynamic light scattering, atomic force microscopy, drug loading efficiency, and drug release studies. Spherical nanoparticles were produced with modal diameter of <300 nm, zeta potential of −20 mv and encapsulation efficiency of 64.1%. In vitro assays of CQ-NP performed in Vero E6 cells, using the MTT-assay, revealed different cytotoxicity levels. Blank nanoparticles (B-NP) were biocompatible. Finally, the antiviral activity tested by the plaque reduction assay revealed greater efficacy for CQ-NP compared to CQ at concentrations equal to or lower than 20 µg mL⁻¹ (p < 0.001). On the other hand, the B-NP had no antiviral activity. The CQ-NP has shown feasible properties and great potential to improve the antiviral activity of drugs.

Synthesis of 4-aminoquinoline-pyrimidine hybrids as potent antimalarials and their mode of action studies

One of the most viable options to tackle the growing resistance to the antimalarial drugs such as artemisinin is to resort to synthetic drugs. The multi-target strategy involving the use of hybrid drugs has shown promise. In line with this, new hybrids of quinoline with pyrimidine have been synthesized and evaluated for their antiplasmodial activity against both CQ(S) and CQ(R) strains of Plasmodium falciparum. These depicted activity in nanomolar range and were found to bind to heme as well as AT rich pUC18 DNA.

H-ras localizes to cell nuclei and varies with the cell cycle

H-Ras functions as a signal switch molecule in numerous signaling pathways in the cytoplasm, requiring H-Ras localization to the inner surface of the cytoplasmic membrane, and H-Ras is considered to be a cytoplasmic protein. Immunoblot studies of cells transformed by overexpression of c-H-ras indicated that H-Ras protein was present in both cytoplasmic and nuclear extracts, suggesting a possible correlation of nuclear H-Ras and cellular transformation. Unexpectedly, additional studies revealed that H-Ras protein was also present in the nuclei of nontransformed and primary mouse cells, which do not overexpress H-Ras. Mouse fibroblast NIH 3T3 cells, L cells, and a primary fibroblast line all had H-Ras present in both cytoplasmic and nuclear extracts. Nuclear extracts of cells synchronized by growth without serum displayed an increasing amount of H-Ras and cyclin D1 as cells grew after serum addition. Treatment with farnesyltransferase inhibitor caused loss of H-Ras from the nucleus. Immunofluorescence in situ studies of nuclei from synchronized cultures showed that H-Ras protein appeared in and disappeared from the nuclei as the cells moved through the growth cycle. This cycling occurred in both nontransformed and ras-transformed cells. Flow cytometry measurements on parallel cultures revealed that the time point at which the greatest percentage of cells were in S phase, for each line, corresponded to appearance of a noticeably stronger in situ signal for H-Ras. H-Ras may participate in nuclear signaling pathways associated with replication in addition to its cytoplasmic signaling functions.

Antiviral activity of chloroquine against human coronavirus OC43 infection in newborn mice

Until recently, human coronaviruses (HCoVs), such as HCoV strain OC43 (HCoV-OC43), were mainly known to cause 15 to 30% of mild upper respiratory tract infections. In recent years, the identification of new HCoVs, including severe acute respiratory syndrome coronavirus, revealed that HCoVs can be highly pathogenic and can cause more severe upper and lower respiratory tract infections, including bronchiolitis and pneumonia. To date, no specific antiviral drugs to prevent or treat HCoV infections are available. We demonstrate that chloroquine, a widely used drug with well-known antimalarial effects, inhibits HCoV-OC43 replication in HRT-18 cells, with a 50% effective concentration (+/- standard deviation) of 0.306 +/- 0.0091 microM and a 50% cytotoxic concentration (+/- standard deviation) of 419 +/- 192.5 microM, resulting in a selectivity index of 1,369. Further, we investigated whether chloroquine could prevent HCoV-OC43-induced death in newborn mice. Our results show that a lethal HCoV-OC43 infection in newborn C57BL/6 mice can be treated with chloroquine acquired transplacentally or via maternal milk. The highest survival rate (98.6%) of the pups was found when mother mice were treated daily with a concentration of 15 mg of chloroquine per kg of body weight. Survival rates declined in a dose-dependent manner, with 88% survival when treated with 5 mg/kg chloroquine and 13% survival when treated with 1 mg/kg chloroquine. Our results show that chloroquine can be highly effective against HCoV-OC43 infection in newborn mice and may be considered as a future drug against HCoVs.

Recycling of chloroquine and its hydroxyl analogue to face bacterial, fungal and viral infections in the 21st century

Chloroquine (CQ) and its hydroxyl analogue hydroxychloroquine (HCQ) are weak bases with a half-century long use as antimalarial agents. Apart from this antimalarial activity, CQ and HCQ have gained interest in the field of other infectious diseases. One of the most interesting mechanisms of action is that CQ leads to alkalinisation of acid vesicles that inhibit the growth of several intracellular bacteria and fungi. The proof of concept of this effect was first used to restore intracellular pH allowing antibiotic efficacy for Coxiella burnetii, the agent of Q fever, and doxycycline plus HCQ is now the reference treatment for chronic Q fever. There is also strong evidence of a similar effect in vitro against Tropheryma whipplei, the agent of Whipple's disease, and a clinical trial is in progress. Other bacteria and fungi multiply in an acidic environment and encouraging in vitro data suggest that this concept may be generalised for all intracellular organisms that multiply in an acidic environment. For viruses, CQ led to inhibition of uncoating and/or alteration of post-translational modifications of newly synthesised proteins, especially inhibition of glycosylation. These effects have been well described in vitro for many viruses, with human immunodeficiency virus (HIV) being the most studied. Preliminary in vivo clinical trials suggest that CQ alone or in combination with antiretroviral drugs might represent an interesting way to treat HIV infection. In conclusion, our review re-emphasises the paradigm that activities mediated by lysosomotropic agents may offer an interesting weapon to face present and future infectious diseases worldwide.

In vitro inhibition of severe acute respiratory syndrome coronavirus by chloroquine

We report on chloroquine, a 4-amino-quinoline, as an effective inhibitor of the replication of the severe acute respiratory syndrome coronavirus (SARS-CoV) in vitro. Chloroquine is a clinically approved drug effective against malaria. We tested chloroquine phosphate for its antiviral potential against SARS-CoV-induced cytopathicity in Vero E6 cell culture. Results indicate that the IC50 of chloroquine for antiviral activity (8.8 +/- 1.2 microM) was significantly lower than its cytostatic activity; CC50 (261.3 +/- 14.5 microM), yielding a selectivity index of 30. The IC50 of chloroquine for inhibition of SARS-CoV in vitro approximates the plasma concentrations of chloroquine reached during treatment of acute malaria. Addition of chloroquine to infected cultures could be delayed for up to 5h postinfection, without an important drop in antiviral activity. Chloroquine, an old antimalarial drug, may be considered for immediate use in the prevention and treatment of SARS-CoV infections.

Role of vacuolar H(+)-ATPase in interferon-induced inhibition of viral glycoprotein transport

We have shown previously that interferon-beta (IFN-beta) induces the alkalinization of trans-Golgi network (TGN) and inhibits the transport of G protein of vesicular stomatitis virus (VSV) in L(B) cells and gD protein of herpes simplex virus (HSV-1) in LMtk- cells transfected with gD cDNA. The vacuolar H(+)-ATPase (V-ATPase) is responsible for maintaining pH in TGN, and V-ATPase-mediated acidification is required for normal transport of proteins. To examine whether alkalinization caused by IFN is mediated through V-ATPase, the activity of V-ATPase was determined in IFN-treated cells by coupling ATP hydrolysis to NADH oxidation. Bafilomycin (Baf) was used as positive control, as it specifically inhibits V-ATPase. The activity of V-ATPase was reduced in IFN-treated or Baf-treated cells compared with untreated cells. Doses of IFN-beta or Baf that neither alter pHi nor inhibit the transport of viral glycoproteins concomitantly inhibited the transport of G and gD proteins in TGN, as demonstrated by indirect immunofluorescence studies, and raised the pH of TGN as demonstrated by a decrease in the uptake of DAMP. Further, the effect of Baf on IFN-induced antiviral activity against VSV was examined to correlate the biologic significance of these findings. Data showed that Baf significantly enhances (5-50-fold) the IFN-induced antiviral activity as demonstrated by viral titers from supernatants. These findings suggest that the inhibition of transport of G and gD proteins by IFN-beta, may be related to the inhibition of V-ATPase-mediated acidification of TGN.

Type I consensus IFN (IFN-con1) gene transfer into KSHV/HHV-8-infected BCBL-1 cells causes inhibition of viral lytic cycle activation via induction of apoptosis and abrogates tumorigenicity in sCID mice

In this study, we investigated the effects of human type I consensus interferon (IFN-con1) (Amgen) gene transfer into body cavity-based lymphomas (BCBL)-1 cells, which are latently infected with Kaposi's sarcoma-associated herpesvirus (KSHV) human herpesvirus-8 (HHV-8). Both the basal and 12-O-tetradecanoyl phorbol-13-acetate (TPA)-stimulated production of KSHV/HHV-8 mature virions was strongly inhibited in genetically modified IFN-producing BCBL-1 cells as compared with parental or control transduced counterparts. A similar inhibition was obtained on treatment of parental BCBL-1 cells with exogenous IFN-con1. The reduction in KSHV/HHV-8 production was associated with a decrease in the basal and TPA-stimulated intracellular amount of the linear form of the viral genome. Interestingly, 25%40% of the IFN-producing BCBL-1 cell population underwent spontaneous apoptosis in vitro. TPA treatment, which did not significantly affect the viability of the parental and control BCBL-1 cells, resulted in the apoptotic death of up to 70% of the IFN-producing cell population. Addition of exogenous IFN-con1 to parental BCBL-1 cells produced similar effects, although less intense. Injection of either parental or control-transduced BCBL-1 cells into SCID mice resulted in progressively growing tumors characterized by an unusually high level of tumor angiogenesis. In contrast, complete tumor regression was observed in all the mice injected either subcutaneously (s.c.) or intraperitoneally (i.p.) with the IFN-producing BCBL-1 cells. These results represent the first evidence that type I IFN can counteract the activation of a productive herpesvirus infection in latently infected tumor cells by the induction of apoptosis, providing an interesting link between the antiviral and antitumor activities of this cytokine. These data suggest the possible advantages of strategies of type I IFN gene transfer (with respect to the use of the exogenous cytokine) for the treatment of patients with some HHV-8-induced malignancies.

The comparative anti-herpes simplex virus effects of human interferons

The mechanism(s) of anti-herpes simplex virus (HSV) activity of interferons (IFNs) have not been clearly identified. We have tested natural and recombinant human IFN-alpha, IFN-beta, and IFN-gamma preparations for their relative anti-HSV activity in human corneal and Vero monkey kidney cells. The relative anti-HSV activities in corneal cells were IFN-beta > rIFN-gamma > IFN-alpha (lymphoblastoid) > rIFN-beta2a = rIFN-alphaA/D. IFN-beta at 100 IU/ml reduced virus yield by 59+/-24%. The relative anti-HSV activity in Vero cells was rIFN-gamma > IFN-beta = IFN-alpha (lymphoblastoid) > rIFN-alphaA/D > rIFN-alpha2a. IFN-gamma at 100 IU/ml reduced virus yields by 90+/-4%. Reducing the multiplicity of infection significantly increased the apparent antiviral activity of all IFNs. The antiviral activity of IFNs could be detected by 4 h after treatment of Vero cells but not until 8 h in corneal cells. Western blot analysis showed that none of the IFNs detectably reduced the levels of immediate-early HSV protein, ICP4, but some reduced ICP0 levels early during infection, the extent and duration of the reduction varying with both IFN and cell type. The greatest effects on viral protein levels were detected in IFN-y-treated Vero cells. These data indicated that the targets of the anti-HSV activities of IFNs can vary with both IFN and cell type.