title: Isolation and characterization of niphatevirin, a human-immunodeficiency-virus-inhibitory glycoprotein from the marine sponge Niphates erecta.
abstract: Anti-human immunodeficiency virus (HIV)-bioassay-guided fractionation of aqueous extracts of the Caribbean sponge Niphates erecta led to isolation of a novel anti-HIV protein, named niphatevirin. The protein was purified to homogeneity by ethanol precipitation, ammonium sulfate precipitation, gel-permeation chromatography and concanavalin-A-Sepharose affinity chromatography. Niphatevirin potently inhibited the cytopathic effects of HIV-1 infection in cultured human lymphoblastoid (CEM-SS) cells; the effective concentration of drug that results in 50% protection of the cells through inhibition of cell lethality, cell-cell fusion and syncytium formation was approximately 10 nM. Delay of addition of niphatevirin to infected cultures by two hours markedly decreased (approximately 50%) cytoprotection; delay of addition by eight hours resulted in no antiviral activity. Niphatevirin bound to CD4 in a manner that prevented the binding of gp120, but did not directly bind gp120. Niphatevirin (6.5 microM) was inactive in both hemagglutination and hemolysis assays. Niphatevirin had a molecular mass of about 19 kDa by matrix-assisted laser-desorption ionization-time of flight (MALDI-TOF) mass spectrometry, and a native molecular mass of approximately 18 kDa by gel-filtration chromatography. The protein had an acidic isoelectric point of 4.2-4.6, and was shown by periodate acid Schiff's staining to be glycosylated.
authors.affiliation: Laboratory of Drug Discovery Research and Development, Frederick Cancer Research and Development Center, Maryland, USA.
authors.forename: B R
authors.initials: BR
authors.lastname: O'Keefe
authors.forename: J A
authors.initials: JA
authors.lastname: Beutler
authors.forename: J H
authors.initials: JH
authors.lastname: Cardellina
authors.forename: R J
authors.initials: RJ
authors.lastname: Gulakowski
authors.forename: B L
authors.initials: BL
authors.lastname: Krepps
authors.forename: J B
authors.initials: JB
authors.lastname: McMahon
authors.forename: R C
authors.initials: RC
authors.lastname: Sowder
authors.forename: L E
authors.initials: LE
authors.lastname: Henderson
authors.forename: L K
authors.initials: LK
authors.lastname: Pannell
authors.forename: S A
authors.initials: SA
authors.lastname: Pomponi
authors.forename: M R
authors.initials: MR
authors.lastname: Boyd
mesh_terms: D000372:Agglutination Tests; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D019380:Anti-HIV Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D000998:Antiviral Agents / Q000737:chemistry; D015704:CD4 Antigens / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D002460:Cell Line; D004229:Dithiothreitol / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D015726:Giant Cells / Q000187:drug effects; D005990:Glycerol / Q000494:pharmacology; D006023:Glycoproteins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D015497:HIV-1 / Q000187:drug effects* / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007369:Interferon Inducers / Q000737:chemistry; D037102:Lectins / Q000737:chemistry; D037121:Plant Lectins; D011161:Porifera / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013696:Temperature
chemical_list: D000596:Amino Acids; D019380:Anti-HIV Agents; D000998:Antiviral Agents; D015704:CD4 Antigens; D002352:Carrier Proteins; D006023:Glycoproteins; D015699:HIV Envelope Protein gp120; D007369:Interferon Inducers; D037102:Lectins; D037121:Plant Lectins; C043696:jacalin; D004492:Edetic Acid; D005990:Glycerol; D004229:Dithiothreitol