Una O'Doherty
Assistant Professor, Dept of Pathology and Laboratory Medicine

Microbiology, Virology and Parasitology Program

Address

265 John Morgan
3620 Hamilton Walk
Philadelphia, PA 19104

Office tel.: 215 573-7273
Lab tel.: 215 573-7781
Fax: 215 573-0879
E-mail: unao@mail.med.upenn.edu

Dr. O'Doherty's Lab webpage

Barnard College: BA (Biochemistry), 1987.

Rockefeller University: PhD (Cellular immunology), 1994.

Cornell Univeristy Medical College: MD (Medicine), 1995.

Research Interests

• Differences between HIV infection of resting and activated CD4+ T cells.
• HIV integration levels in subsets of resting CD4+ T cells and patient samples.
• Gene therapy of resting CD4+ T cells.

Key words: HIV, latency, reservoirs, dendritic cells, viral pathogenesis, proviral integration, retrovirus, virology, T cell activation, resting T cells, gene therapy, naïve, memory resting CD4+ T cells.

Description of Research

A new picture is emerging: while much of the scientific community has studied HIV infection of activated CD4+ T cells, evidence has accumulated that direct infection of resting CD4+ T cells occurs and that it differs significantly from infection of activated cells. Now it makes sense to work toward understanding infection of resting CD4+ T cells both because these cells are the major infected cell type during acute infection and because latent infection of resting cells is a major reason that HIV is incurable. There has been great success in targeting HIV infection of activated CD4+ T cells; indeed, current treatments can reduce plasma HIV-1 levels to undetectable. It follows that a better understanding of HIV infection of resting CD4+ T cells may lead to new therapies that target resting cells and prevent or treat acute HIV-1 infection.

We developed an in vitro system in which resting CD4+ T cells can be efficiently infected by HIV. Using this system, we demonstrated that HIV integrates into resting cells without entering the cell cycle and that these infected cells can be stimulated to produce new virions. Therefore, this system serves as an in vitro model of latent HIV infection.

We also developed sensitive, quantitative assays to measure HIV binding, fusion, reverse transcription, and integration in resting and activated CD4+ T cells. Our integration assay detects integration levels as low as 1 provirus in 100,000 resting cells. Moreover, the assay is sufficiently sensitive to measure integration in low inoculum infections and in samples from HIV-infected patients.

Using these tools, we are focusing on three main projects in our lab: (1) dissecting the differences between HIV infection of resting and activated CD4+ T cells, (2) expanding the applications of our integration assay, and (3) designing a gene therapy vector that transduces resting CD4+ T cells efficiently.

Selected Publications

Swiggard WJ, Baytop C, Yu JJ, Dai J, Li C, Schetzenmair R, Theodosopoulos T, O'Doherty U: Human Immunodeficiency Virus type 1 can establish latent infection in resting CD4+ T cells in the absence of activating stimuli. J.Virol. 2005.

Agosto LM, Yu JJ, Dai J, Kaletsky R, Monie D, O'Doherty U: HIV-1 integrates into resting CD4+ T cells even at low inoculums as demonstrated with an improved assay for HIV-1 integration. Virology 2007.

Plesa G., Dai J., Baytop C., Riley J.L., June C.H., Una O'Doherty: Addition of deoxynucleosides enhances HIV-1 integration and 2LTR formation in resting CD4+ T cells. J. Virol. December 2007.

Yu, J. J., Wu, T. L., Liszewski, M.K., Dai, J., Swiggard, W. J., Baytop, C., Frank, I., Levine, B. L., Yang, W., Theodosopoulos, T., O'Doherty, U.: A more precise HIV integration assay designed to detect small differences finds lower levels of integrated DNA in HAART treated patients. Virology. 2008 Sep 15;379(1):78-86.

Search PubMed for more articles

Lab

Rotation Projects

1. Dissect the differences between HIV infection of resting and activated CD4+ T cells.
   • Identify viral factors that play a critical role in infection of resting cells.
   • Define the mechanisms by which these viral factors act.
   • Compare HIV integration sites in resting and activated CD4+ T cells.
2. Expand the applications of our HIV integration assay.
• Compare integration levels in subsets of CD4+ T cells and other CD4+ cells such as dendritic cells.
• Monitor integration in samples from HIV-infected patients.
3. Design a gene therapy vector that transduces resting CD4+ T cells efficiently.

Lab personnel

Jenny Yu, research specialist
Luis Agosto, graduate student
Matt Pace, graduate student
Megan Liszewski, research specialist