Effects of suramin on in vitro HBsAg production by PLC/PRF/5 cells and hepatitis B virus DNA polymerase activity

Suramin is a potent inhibitor of Chikungunya and Ebola virus cell entry

BACKGROUND

Chikungunya virus (CHIKV) is a mosquito-transmitted alphavirus that causes high fever, rash, and recurrent arthritis in humans. It has efficiently adapted to Aedes albopictus, which also inhabits temperate regions and currently causes large outbreaks in the Caribbean and Latin America. Ebola virus (EBOV) is a member of the filovirus family. It causes the Ebola virus disease (EDV), formerly known as Ebola hemorrhagic fever in humans and has a mortality rate of up to 70 %. The last outbreak in Western Africa was the largest in history and has caused approximately 25,000 cases and 10,000 deaths. For both viral infections no specific treatment or licensed vaccine is currently available. The bis-hexasulfonated naphthylurea, suramin, is used as a treatment for trypanosome-caused African river blindness. As a competitive inhibitor of heparin, suramin has been described to have anti-viral activity.

METHODS

We tested the activity of suramin during CHIKV or Ebola virus infection, using CHIKV and Ebola envelope glycoprotein pseudotyped lentiviral vectors and wild-type CHIKV and Ebola virus.

RESULTS

Suramin efficiently inhibited CHIKV and Ebola envelope-mediated gene transfer while vesicular stomatitis virus G protein pseudotyped vectors were only marginally affected. In addition, suramin was able to inhibit wild-type CHIKV and Ebola virus replication in vitro. Inhibition occurred at early time points during CHIKV infection.

CONCLUSION

Suramin, also known as Germanin or Bayer-205, is a market-authorized drug, however shows significant side effects, which probably prevents its use as a CHIKV drug, but due to the high lethality of Ebola virus infections, suramin might be valuable against Ebola infections.

Suramin Inhibits Chikungunya Virus Entry and Transmission

The mosquito-borne Chikungunya virus (CHIKV) is a profound global threat due to its high rate of contagion and the lack of vaccine or effective treatment. Suramin is a symmetric polyanionic naphthylurea that is widely used in the clinical treatment of parasite infections. Numerous studies have reported the broad antiviral activities of suramin; however, inhibition effects against CHIKV have not yet been demonstrated. The aim of this study was thus to investigate the antiviral effect of suramin on CHIKV infection and to elucidate the molecular mechanism underlying inhibition using plaque reduction assay, RT-qPCR, western blot analysis, and plaque assay. Microneutralization assay was used to determine the EC₅₀ of suramin in the CHIKV-S27 strain as well as in three other clinical strains (0611aTw, 0810bTw and 0706aTw). Time-of-addition was used to reveal the anti-CHIKV mechanism of suramin. We also evaluated anti-CHIKV activity with regard to viral entry, virus release, and cell-to-cell transmission. Cytopathic effect, viral RNA, viral protein, and the virus yield of CHIKV infection were shown to diminish in the presence of suramin in a dose-dependent manner. Suramin was also shown the inhibitory activities of the three clinical isolates. Suramin inhibited the early progression of CHIKV infection, due perhaps to interference with virus fusion and binding, which subsequently prevented viral entry. Results of a molecular docking simulation indicate that suramin may embed within the cavity of the E1/E2 heterodimer to interfere with their function. Suramin was also shown to reduce viral release and cell-to-cell transmission of CHIKV. In conclusion, Suramin shows considerable potential as a novel anti-CHIKV agent targeting viral entry, extracellular transmission, and cell-to-cell transmission.

Suramin exerts in vivo cytokine modulatory properties on splenocytes from experimental allergic encephalomyelitis-induced SJL mice: implications for autoimmune disease therapy

The present study sought to examine the immunopharmacologic effects of suramin on splenocytes from experimental allergic encephalomyelitis (EAE)-induced mice, taken in line with a previous observed action of suramin in ameliorating EAE. Suramin, a polysulfonated napthylurea, decreased the proliferation of T cells, in the presence of various stimuli, such as guinea pig myelin basic protein (MBP), mouse spinal cord homogenate (MSCH), bovine proteolipid protein (PLP), P1 (synthetic peptide 139-151 of PLP), and Mycobacterium tuberculosis (MTB). Suramin inhibited T cell proliferation in a dose-dependent manner. However, cytokine assays revealed that suramin increased antigen-induced levels of IL-4, whilst IFN-gamma levels were decreased. Using various doses of suramin (25, 15, and 5 micrograms/g), its cytokine modulatory effect displayed a consistent dose-dependent activity in vivo. This cytokine modulation commenced on week 2 after immunization and persisted all throughout the drug administration period, up to the 4th week. These results indicate that the prospects of using suramin in the treatment of multiple sclerosis may be feasible.

Inhibition of growth of HIV by human natural interferon in vitro

The effect of human natural interferons (IFN) alpha, beta, and gamma on the replication of human immunodeficiency virus (HIV) strain LAV in T cell lines TALL-1 and CCRF-CEM and peripheral blood lymphocytes (PBL) was studied. The growth of TALL-1 was moderately sensitive to these IFN, whereas that of CCRF-CEM was resistant to them. The progeny virus yield of LAV in TALL-1 at the time of its peak was reduced to 10% of the control level at IFN-alpha, beta, and gamma concentrations of 3, 11, and 23 IU/ml, respectively. These concentrations of IFN-alpha, beta, and gamma did not affect the cell growth. In CCRF-CEM, IFN-alpha, beta, and gamma at the concentration of 50, 60, and 76 IU/ml reduced the progeny virus to 10% of the control level. The virus growth in PBL was more sensitive to IFN than that in CCRF-CEM. The progeny virus yield was reduced to 10% of the control level by IFN-alpha and beta concentrations of 5 IU/ml and less than 5 IU/ml, respectively.