A chemically synthesized peptide representing the C-terminal subunit (p13-C) of the p13 protein of GB virus B (GBV-B), the most closely related virus to hepatitis C virus (HCV) showed ion channel activity in artificial lipid bilayers. The channels had a variable conductance and were more permeable to potassium ions than to chloride ions. Amantadine but not hexam-ethylene amiloride (HMA) inhibited the ion channel function of p13-C in the lipid membranes. However, neither agent was able to inhibit the replication and secretion of GBV-B from virus-infected cultured marmoset hepatocytes, which were harvested from a marmoset that was infected in vivo or inhibit replication after in vitro infection of naive hepatocytes. These data suggest that the GBV-B ion channel, contrary to the data derived from the lipid membranes, is either resistant to amantadine or that virus replication and secretion are independent of ion channel function. As the p7 protein of HCV also has ion channel activity that is apparently resistant to amantadine in vivo, the former possibility is most likely. Ion channels are likely to have an important role in the life cycle of many viruses and compounds that block these channels may prove to be useful antiviral agents.
ErkerJ.C., DesaiS.M., LearyT.P., ChalmersM.L., MontesC., MushahwarI.K.Genomic analysis of two GB virus A variants isolated from captive monkeys.J Gen Virol1998; 79: 41–45.
3.
MuerhoffA.S., LearyT.P., SimonsJ.N.Genomic organization of GB viruses A and B: two new members of the Flaviviridae associated with GB agent hepatitis.J Virol1995; 69: 5621–5630.
4.
BrightH., CarrollA.R., WattsP.A., FentonR.J.Development of a GB virus B marmoset model and its validation with a novel series of hepatitis C virus NS3 protease inhibitors.J Virol2004; 78: 2062–2071.
5.
BeamesB., ChavezD., LanfordR.E.GB virus B as a model for hepatitis C virus.Ilar J2001; 42: 152–160.
6.
SbardellatiA., ScarselliE., VerschoorE., De TomassiA., LazzaroD., TraboniC.Generation of infectious and transmissible virions from a GB virus B full-length consensus clone in tamarins.J Gen Virol2001; 82: 2437–2448.
7.
BukhJ., ApgarC.L., GovindarajanS., PurcellR.H.Host range studies of GB virus-B -hepatitis agent, the closest relative of hepatitis C virus, in New World monkeys and chimpanzees.J Med Virol2001; 65: 694–697.
8.
BeamesB., ChavezD., GuerraB., NotvallL., BraskyK.M., LanfordR.E.Development of a primary tamarin hepatocyte culture system for GB virus-B: a surrogate model for hepatitis C virus.J Virol2000; 74: 11764–11772.
9.
DuffK.C., AshleyR.H.The transmembrane domain of influenza A M2 protein forms amantadine-sensitive proton channels in planar lipid bilayers.Virology1992; 190: 485–489.
10.
EwartG.D., SutherlandT., GageP.W., CoxG.B.The Vpu protein of human immunodeficiency virus type 1 forms cation-selective ion channels.J Virol1996; 70: 7108–7115.
11.
MeltonJ.V., EwartG.D., WeirR.C., BoardP.G., LeeE, GageP.W.Alphavirus 6K proteins form ion channels.J Biol Chem2002; 277: 46923–46931.
12.
PillerS.C., EwartG.D., PremkumarA., CoxG.B., GageP.W.Vpr protein of human immunodeficiency virus type 1 forms cation-selective channels in planar lipid bilayers.Proc Natl Acad Sci USA1996; 93: 111–115.
13.
PintoL.H., HolsingerL.J., LambR.A.Influenza virus M2 protein has ion channel activity.Cell1992; 69: 517–528.
14.
PremkumarA., WilsonL., EwartG.D., GageP.W.Cation-selective ion channels formed by p7 of hepatitis C virus are blocked by hexamethylene amiloride.FEBS Lett2004; 557: 99–103.
15.
SunstromN.A., PremkumarL.S., PremkumarA., EwartG., CoxG.B., GageP.W.Ion channels formed by NB, an influenza B virus protein.J Membr Biol1996; 150: 127–132.
16.
GonzalezM.E., CarrascoL.Viroporins.FEBS Lett, 2003; 552: 28–34.
17.
TostesonM.T., PintoL.H., HolsingerL.J., LambR.A.Reconstitution of the influenza virus M2 ion channel in lipid bilayers.J Membr Biol1994; 142: 117–126.
18.
FischerW.B., PitkeathlyM., SansomM.S.Amantadine blocks channel activity of the transmembrane segment of the NB protein from influenza B.Eur Biophys J, 2001; 30: 416–420.
19.
KatoN., EggersH.J.Inhibition of uncoating of fowl plague virus by l-adamantanamine hydrochloride.Virology1969; 37: 632–641.
20.
RuigrokR.W., HirstE.M., HayA.J.The specific inhibition of influenza A virus maturation by amantadine: an electron microscopic examination.J Gen Virol1991; 72: 191–194.
21.
GriffinS.D., BealesL.P., ClarkeD.S.The p7 protein of hepatitis C virus forms an ion channel that is blocked by the antiviral drug, Amantadine.FEBS Lett2003; 535: 34–38.
22.
PavlovicD., NevilleD.C., ArgaudO.The hepatitis C virus p7 protein forms an ion channel that is inhibited by long-alkyl-chain iminosugar derivatives.Proc Natl Acad Sci USA2003; 100: 6104–6108.
23.
SakaiA., ClaireM.S., FaulkK.The p7 polypeptide of hepatitis C virus is critical for infectivity and contains functionally important genotype-specific sequences.Proc Natl Acad Sci USA2003; 100: 11646–11651.
24.
GriffinD.C., HarveyR., ClarkeD.S., BarclayW.S., HarrisM., RowlandsD.J.A conserved basic loop in hepatitis C virus p7 protein is required for amantadine-sensitive ion channel activity in mammalian cells but is dispensible for localization to mitochondria.J Gen Virol2004; 85: 451–461.
25.
GhibaudoD., CohenL., PeninF., MartinA.Characterization of GB virus B polyprotein processing reveals the existence of a novel 13 kDa protein with partial homology to hepatitis C virus p7 protein.J Biol Chem2004; 279: 24965–24975.
26.
TakikawaS., EngleR.E., EmersonS.U., PurcellR.H., BukhJ.Only the C-terminal subunit of the GBV-B P13 protein is required for infectivity in tamarins: Generation of a recombinant GBV-B virus with a P7 protein.12th International Symposium on HCV and Related Viruses. 2–6 October 2005, Montreal, Canada. Abstract O-32.
27.
BukhJ., ApgarC.L., YanagiM.Toward a surrogate model for hepatitis C virus: An infectious molecular clone of the GB virus-B hepatitis agent.Virology1999; 262: 470–478.
28.
EwartG.D., MillsK., CoxG.B., GageP.W.Amiloride derivatives block ion channel activity and enhancement of virus-like particle budding caused by HIV-1 protein Vpu.Eur Biophys J2002; 31: 26–35.
29.
HaradaT., TautzN., ThielH.J.E2-p7 region of the bovine diarrhea virus polyprotein: processing and functional studies.J Virol2000; 74: 9498–9506.
30.
PremkumarA., HoranC.R., GageP.W.Dengue virus M protein C-terminal peptide (DVM-C) forms ion channels.J Membr Biol2005; 204: 33–38.
31.
TuluvathP.J., MaheshwariA., MehdiJ.Randomised, double blind, placebo controlled trial of interferon, ribavirin, and amantadine versus interferon, ribavirin, and placebo in treatment naive patients with chronic hepatitis C.Gut2003; 53: 130–135.
32.
SaunierB., TriyatniM., UlianichL., MaruvadaP., YenP., KohnL.D.Role of the asialoglycoprotein receptor in binding and entry of hepatitis C virus structural proteins in cultured human hepatocytes.J Virol2003; 77: 546–559.
