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Jeffrey J. DeStefano
Director of MOCB Graduate Concentration Area (BISI
Graduate Program)
Professor
Ph.D.- University of Connecticut, 1990
Telephone: 301-405-5449
Fax: (301) 314-9489
E-mail:
jdestefa@umd.edu
Lab Web Page
Research Interests: HIV and poliovirus replication and recombination
Research in my laboratory has focused
on studying the role of HIV-reverse transcriptase (RT) and
nucleocapsid protein (NC) in the processes of retroviral
recombination and replication. We also analyze basic properties of
these proteins including how they interact with specific nucleic
acid sequences involved in replication and how the activities of the
proteins as defined in the test tube, function in cellular
replication. Other projects are aimed at isolating nucleic acid
inhibitors (aptamers) that can bind very tightly to RT and inhibit
its function. We also study poliovirus replication, specifically by
examining the polymerase (3Dpol) and 3AB proteins. Recombination is
one of the mechanisms that retroviruses like HIV use to generate
genetic diversity. By producing genetic variants viruses are able to
circumvent the host immune response and escape drug therapies.
Currently we work on several aspects of recombination, including the
basic mechanism(s) by which recombination occurs, NC’s role in
stimulating recombination, and the role of specific viral sequences
in recombination. Our basic approach has been to use in vitro
systems that mimic recombination and replication in the cell to
understand the processes. Our group also collaborates with those of
Drs. Eric Arts and Matteo Negroni on a project to study how
intersubtype recombinants arise (Baird et al., 2006). These are HIV
viruses that form by recombination between two different subgroups
(A and D for example to produce an A/D recombinant). Intersubtype
recombinants are becoming more prevalent, especially in Asia and
Africa. This could complicate attempts to produce effective vaccines
and drugs as therapies developed against the more common B and C
type viruses may not be effective against other types or
intersubtypes. Another goal has been to produce in vitro
replication systems that more closely mimic what occurs in the cell.
Such systems could potentially be used to test reverse transcription
and recombination inhibitors. Recently conditions that allow the
production of near genome length DNA synthesis products have been
uncovered in the lab (Anthony and DeStefano, 2007). This is a major
step as previous systems yielded mostly small products. Another
recent highlight is the discovery of primer-template sequences that
bind HIV-RT with high affinity (DeStefano and Cristofaro, 2006). The
sequences closely resembled the HIV polypurine tract (ppt) sequence
which is pivotal for genome replication. The results suggested that
HIV-RT has co-evolved with this region to ensure tight binding and
efficient replication. We are currently analyzing other retroviruses
to see if all RTs evolved to bind their cognate ppt sequence
tightly. In addition, this information was used to develop a small
nucleic acid inhibitor of HIV-RT that we are currently testing to
see if it can inhibit viral infection of cells. Recent highlights of
our poliovirus work include the finding that 3AB is a nucleic acid
chaperone protein (DeStefano and Titlope, 2006). Chaperones like HIV
NC protein, help nucleic acids fold properly and in the case of NC,
are involved in several steps of the virus life cycle. Protein 3AB
is important for anchoring poliovirus replication complexes to
internal cell membranes (3A portion) and serving as the “protein
primer” for genome replication (3B portion). It has been studied for
several years and our lab was the first to recognize its chaperone
activity. Site-directed mutagenesis is currently by used to map the
chaperone function of the protein. By studying unique aspects of the
HIV and poliovirus life cycle we hope to contribute to new therapies
that exploit these unique functions.
In my capacity as the director of the
CBMG graduate program, I teach an orientation course for in-coming
graduate students, which provides an intensive overview of faculty
research programs, research project design, career opportunities,
academic ethics, and other issues important to graduate students.
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