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Isolation and characterization of a novel class of potent anti‐HIV proteins from an Australian soft coral (975.6)
Author(s) -
Ramessar Koreen,
Xiong Chang,
Krumpe Lauren,
Buckheit Robert,
Wilson Jennifer,
McMahon James,
O'Keefe Barry
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.975.6
Subject(s) - glycoprotein , gp41 , biology , biochemistry , virus , entry inhibitor , viral entry , virology , chemistry , viral replication , antibody , immunology , epitope
An estimated 34 million people are living with the human immunodeficiency virus (HIV) worldwide. Increasing resistance to antiretrovirals (ARVs) challenges current therapies and it is critical to identify novel non‐ARV anti‐HIV agents to prevent infection. Here we report the isolation of a novel class of proteins, called Cnidarins, from the soft coral Synthecium sp. (phylum Cnidaria). The proteins were purified by sequential ethanol and ammonium sulphate precipitation followed by hydrophobic interaction chromatography. The purified proteins, CNID‐1, CNID‐2 and CNID‐3, were monomers of ~170 amino acids with molecular weights of ~18 kDa. CNID‐1 and CNID‐3 (fully sequenced) showed no significant homology (>25%) to any known protein. All three cnidarins showed picomolar to low‐nanomolar activity against laboratory strains and primary isolates of HIV‐1. They inhibited viral fusion in a concentration‐dependant manner but not viral attachment, indicating the proteins’ antiviral effects occur after initial virus‐to‐cell attachment but prior to viral entry. CNID‐1 was the most potent (EC 50 of 85 pM) and bound to viral glycoproteins gp120 and gp41 equally in a concentration‐dependant manner, but not to other glycoproteins or soluble CD4. Pre‐treatment with CNID‐1 did not block sCD4 binding to gp120 and vice versa and its gp120 binding was independent of glycosylation. Pre‐treatment with other potent antiviral proteins, cyanovirin and scytovirin, did not affect CNID‐1 binding to gp120 and gp41, and seemed to promote slightly better binding of CNID‐1, while griffithsin pre‐treatment reduced CNID‐1 binding but not completely. Recombinant production in E.coli resulted in C‐terminal truncated forms of CNID‐1 (14‐16kDa, EC 50 of 45‐150nM). Ongoing work includes optimizing expression conditions to produce fully active rCNID‐1. Cnidarins represent a novel class of proteins that target viral fusion and inhibit HIV infection in a manner different from any currently identified anti‐HIV agent. Grant Funding Source : Supported by the Intramural Research Program, National Cancer Institute