Scaleable manufacture of HIV-1 entry inhibitor griffithsin and validation of its safety and efficacy as a topical microbicide component
- Barry R. O'Keefea,
- Fakhrieh Vojdanib,
- Viviana Buffac,
- Robin J. Shattockc,
- David C. Montefiorid,
- James Bakkee,
- Jon Mirsalise,
- Anna-Lisa d'Andreae,
- Steven D. Humef,
- Barry Bratcherf,
- Carrie J. Saucedoa,g,
- James B. McMahona,
- Gregory P. Pogueb and
- Kenneth E. Palmerb,h,1
- aMolecular Targets Development Program, National Cancer Institute at Frederick, Frederick, MD 21702;
- bIntrucept Biomedicine, Owensboro, KY 42301;
- cSaint George's Hospital Medical School, University of London, London SW17 0RE, United Kingdom;
- dDepartment of Surgery, Duke University School of Medicine, Durham, NC 27708;
- eSRI International, Menlo Park, CA 94025;
- fKentucky Bioprocessing, Owensboro, KY 42301;
- gSAIC-Frederick, Frederick, MD 21702; and
- hDepartment of Pharmacology and Toxicology and James Graham Brown Cancer Center, University of Louisville School of Medicine, Louisville, KY 40292
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Communicated by Charles J. Arntzen, Arizona State University, Tempe, AZ, February 12, 2009 (received for review November 1, 2008)
Abstract
To prevent sexually transmitted HIV, the most desirable active ingredients of microbicides are antiretrovirals (ARVs) that directly target viral entry and avert infection at mucosal surfaces. However, most promising ARV entry inhibitors are biologicals, which are costly to manufacture and deliver to resource-poor areas where effective microbicides are urgently needed. Here, we report a manufacturing breakthrough for griffithsin (GRFT), one of the most potent HIV entry inhibitors. This red algal protein was produced in multigram quantities after extraction from Nicotiana benthamiana plants transduced with a tobacco mosaic virus vector expressing GRFT. Plant-produced GRFT (GRFT-P) was shown as active against HIV at picomolar concentrations, directly virucidal via binding to HIV envelope glycoproteins, and capable of blocking cell-to-cell HIV transmission. GRFT-P has broad-spectrum activity against HIV clades A, B, and C, with utility as a microbicide component for HIV prevention in established epidemics in sub-Saharan Africa, South Asia, China, and the industrialized West. Cognizant of the imperative that microbicides not induce epithelial damage or inflammatory responses, we also show that GRFT-P is nonirritating and noninflammatory in human cervical explants and in vivo in the rabbit vaginal irritation model. Moreover, GRFT-P is potently active in preventing infection of cervical explants by HIV-1 and has no mitogenic activity on cultured human lymphocytes.
Footnotes
- 1To whom correspondence should be addressed. E-mail: kepalm02{at}gwise.louisville.edu
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Author contributions: B.R.O., F.V., V.B., R.J.S., D.C.M., J.M., A.-L.d., B.B., J.B.M., G.P.P., and K.E.P. designed research; B.R.O., F.V., V.B., D.C.M., J.B., A.-L.d., S.D.H., C.J.S., and K.E.P. performed research; B.R.O., G.P.P., and K.E.P. contributed new reagents/analytic tools; B.R.O., F.V., V.B., R.J.S., D.C.M., J.B., J.M., A.-L.d., S.D.H., and K.E.P. analyzed data; and B.R.O. and K.E.P. wrote the paper.
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Conflict of interest: F.V., G.P.P., and K.E.P. are members of Intrucept Biomedicine, which is commercializing plant-expressed GRFT. B.R.O. and J.B.M. are listed as inventors on patent applications related to GRFT.
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See Commentary on page 6029.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0901506106/DCSupplemental.
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Freely available online through the PNAS open access option.
