Pediatrics

Research Overview

My lab works on the basic biology of parvovirus B19 and the development of parvovirus B19 as a gene therapy vector. Due to its inherent tropism for the erythroid progenitor cell population in the bone marrow, the only cells that support B19 replication, this virus is an attractive candidate for gene therapy of bone marrow-resident cells. In 1993 the primary receptor for parvovirus B19 binding to human cells was reported to be the blood group P antigen, and we identified a5B1 integrin as co-receptor for viral entry (see Blood 2003). We also showed that viral entry strictly depends on the functional activation of B1 integrins and demonstrated that cross-talk between B1 and B2/B3 integrins is involved in the functional recruitment of B1 integrins as co-receptors for B19 entry into human hematopoietic cells. Our current research focuses on two areas: the increase in packaging efficiency of recombinant parvovirus B19 vectors and the re-targeting of the vectors to non-erythroid cells in the human bone marrow.

Recombinant B19 vectors are generated by packaging AAV2 genomes (AAV2 ITR-promoter-gene of interest - AAV2 ITR) into parvovirus B19 capsids with the help of AAV2 Rep proteins. Since the mechanism of packaging has neither been fully resolved for AAV2 nor B19, we use structural analysis and mutation studies to generate chimeric AAV2-B19 capsids in order to identify components of the AAV2 capsids that are required for AAV Rep protein binding and packaging of AAV2 DNA into B19 capsids. We recently successfully swapped the AAV2 5-fold channel on B19 capsids and, although we observed only a slight increase in DNA insertion, surprisingly, the chimeric vectors showed substantially improved capsid stability and transduction efficiency. We currently investigate the underlying mechanism(s) and evaluate additional swaps of AAV2 capsid components onto B19 capsids.

Our second focus, the re-targeting of B19 to non-erythroid bone marrow cells, has led us to generate parvovirus B19 vectors which lack the P antigen binding site and have instead a HER2/neu-interacting peptide inserted into the surface-exposed loop of viral capsid protein VP2. These novel vectors proved to target HER2/neu-positive cells specifically and we are now in the process to determine their targeting capability in vivo using HER2/neu-positive bone marrow-resident cancer cells as a model. Besides being amplified in breast cancer cells, HER2/neu, has been demonstrated to be expressed on ~40% of childhood medulloblastomas whereas it is undetectable in normal cerebellum and other brain tissue. We will evaluate our novel HER2/neu-targeting B19 vectors in a murine medulloblastoma model with the goal to target medulloblastoma metastases in pediatric patients.

About

Dr. Weigel-Van Aken received her M.D. degree from the University of Heidelberg in Germany and underwent clinical training and performed a post-doctoral research fellowship in Molecular Cardiology at the University of Muenster, Germany. She received a Post-doctoral Research Fellowship from the primary German Government Research Funding Agency 'Deutsche Forschungsgemeinschaft' and moved to the US to perform post-doctoral research at the Krannert Institute of Cardiology, in the Department of Microbiology and Immunology and at the Walther Oncology Center at Indiana University. In 2004 she joined the University of Florida as an Assistant Professor. Dr. Weigel-Van Aken’s research has received an IRG Junior Investigator Award from the American Cancer Society and a New Investigator Research Grant from the Florida Department of Health Bankhead-Coley Cancer Research Program.

Key Publications

Additional publications can be found in PubMed.

1. Zhong L, Li B, Mah CS, Govindasamy L, Agbandje-McKenna M, Cooper M, Herzog RW, Zolotukhin I, Warrington KH Jr, Weigel-Van Aken AK, Hobbs JA, Zolotukhin S, Muzcyzka N, Srivastava A. Next generation of adeno-associated virus 2 vectors: point mutations in tyrosines lead to high-efficiency transduction at lower doses. Proc Natl Acad Sci USA 105: 7827-7832, 2008.
2. Weigel-Kelley KA., Yoder MC, Chen L, Srivastava A. Role of integrin cross-regulation in parvovirus B19 targeting. Hum Gene Ther, 17: 909-20, 2006.
3. Weigel-Kelley KA, Yoder MC, Srivastava A. a5B1 integrin as a cellular co-receptor for human parvovirus B19: Requirement of functional activation of B1 integrin for viral entry. Blood 102: 3729-33, 2003.
4. Weigel-Kelley KA, Srivastava A. Recombinant human parvovirus B19 vectors. Pathol. Biol., 50: 295-306, 2002.
5. Weigel-Kelley KA, Yoder MC, Srivastava A. Recombinant human parvovirus B19 vectors: Erythrocyte P antigen is necessary but not sufficient for successful transduction of human hematopoietic cells. J. Virol., 75 (9): 4110-4116, 2001.
6. Ponnazhagan S, Weigel KA, Raikwar SP, Mukherjee P, Yoder MC, Srivastava A. Recombinant human parvovirus B19 vectors: erythroid cell-specific delivery and expression of transduced genes. J. Virol., 72 (6): 5224-30, 1998.