Croyle, Maria A., Ph.D.
Biochemical Modification of Viruses to Evade the Immune Response
Recombinant viruses were originally thought to be perfect 'Trojan horses' for gene therapy due to their inherent ability to efficiently transduce cellular targets to support their own replication. Their use is limited, however, by the fact that they are rapidly cleared from the circulation by the immune system preventing them from reaching their target and reducing transduction efficiency if a second dose is needed. This fostered a decade of research devoted to genetic and molecular manipulation of the virus genome and capsid proteins. Animals treated with these modified viruses, however, still experience acute toxicity initiated by the innate immune response against capsid proteins.
PEGylation, a method for the modification of virus proteins by covalent attachment of polyethylene glycol (PEG) and originally pioneered to reduce the immune response generated against therapeutic proteins, does not significantly compromise virus activity and extends the half-life of the virus in the systemic circulation. This method also significantly reduces inflammatory cytokines and cytotoxic T cells during the innate immune response and protects vectors from inactivation by complement, neutralizing antibodies and degradation in the gastrointestinal tract. Current research in the laboratory focuses on characterization of viruses modified by polymers with properties similar to PEG. Other work in this area focuses on embedding recombinant viruses in complex polymer matricies to protect the virus from harsh physiological environments and the immune system as well as maintain continuous delivery of virus over extended periods of time without developing tolerance to the vector or the transgene product.
Project Funding: Past and Present
Southwest National Primate Research Center (SNPRC) Pilot Project Grant
UT Undergraduate Research Fellowships
Le, H. T., Yu, Q. C., Wilson, J. M. and Croyle, M. A. Utility of PEGylated Recombinant Adeno-Associated Viruses for Gene Transfer. J. Control. Rel. 2005 108(1):161-177.
Croyle, M. A., Le, H., Linse, K., Ming, X., Toietta, G., Beaudet, A. and Pastore, L. PEGylated Helper-Dependent Adenoviral Vectors: Highly Efficient Vectors with an Enhanced Safety Profile. Gene Ther. 2005 12(7):579-588.
Croyle, M. A. Callahan, S. M., Auricchio, A., Schumer, G., Wilson, J. M., Linse, K., Brunner, L. J. and Kobinger, G. P. PEGylation of a Vesicular Stomatitis Virus G Pseudotyped Lentiviral Vector Prevents Inactivation in Serum. J. Virol. 2004 78(2):912-921.
Cheng, X., Ming, X. and Croyle, M. A. PEGylated Adenoviruses Enhance Gene Delivery to the Intestinal Epithelium by the Oral Route. Pharm. Res. 2003 20(9):1444-1451.
Croyle, M. A., Chirmule, N., Zhang, Y. and James M. Wilson. PEGylation of E-1 Deleted Adenovirus Vectors Allows Significant Gene Expression upon Re-administration to Liver. Hum. Gene Ther. 2002 13(15):1887-1900.
Croyle, M. A., Chirmule, N., Zhang, Y. and Wilson, J. M. "Stealth" Adenoviruses Blunt Cell Mediated and Humoral Immune Responses Against the Virus and Allow for Significant Gene Expression upon Re-administration for Gene Therapy to the Lung. J. Virol. (2001) 75(10):4792-4801.
Croyle, M. A., Yu, Q. C. and Wilson, J. M. Development of a Rapid Method for the PEGylation of Adenoviruses with Enhanced Transduction and Improved Stability Under Harsh Storage Conditions. Human Gene Therapy. (2000) 11:1713-1722.
Wonganan, P., and Croyle, M.A. PEGylated Adenoviruses: From Mice to Monkeys. 2010 Viruses. 2(2): 468-502.
Wonganan, P., Clemens, C.C., Brasky, K., Pastore, L., and Croyle, M. A. 2011 Species Differences in the Pharmacology and Toxicology of PEGylated Helper-Dependent Adenovirus. Molec. Pharm. 8 (1):78-92
Recent Presentations at National and International Meetings
BioKorea 2007 International Biotechnology Conference. September 12-14, 2007. Maria A. Croyle, invited speaker. Talk title: "Pharmacology and Toxicology of Modified Recombinant Viruses for Vaccine and Gene Transfer".
Tenth Annual Meeting American Association Of Gene Therapy, Seattle, W.A. May 30-June 3, 2006.
Fifteenth Annual Meeting of the American Association of Pharmaceutical Scientists. San Antonio, TX. October 29 to November 2, 2006.
College of Pharmacy
The University of Texas
2409 University Ave.
Austin, TX, USA
Email Address: pharmacy
Dr. Bill Williams has been named editor-in-chief of AAPS PharmSciTech, the online research journal of the American Association of Pharmaceutical Scientists.