Joseph P. Casazza, M.D., Ph.D.

My work at the NIH concentrates on two aspects of HIV infection: the control of HIV-infection by the immunologic mechanism and the description of the changes in the CD4 T cell  transcriptome caused by HIV-infection.  In collaboration with individuals at the VRC, the California Institute of Technology and the Ragon Institute I am responsible for a clinical trial in which an AAV vector carries the coding sequence for VRC07, a potent broadly neutralizing Ab, into muscle cells of HIV-infected individuals on effective anti-retroviral therapy. In some individuals production of VRC07 occurred at ug/ml serum quantities for over 3 years. Although this level of VRC07 is not protective, this study shows that it is possible to side-step some of the difficulties in producing an immunogen capable of inducing a broadly neutralizing antibody by using a viral vector to transduction muscle cells.  I have also established methods to identify and sort live HIV-infected CD4 T cells. Unlike matrix proteins, envelope proteins are fully mature when transported to the surface of CD4 T cells.  By using fluorescently labeled broadly neutralizing antibodies that bind HIV envelope protein expressed on the surface of CD4 T cells, it is possible to use index sorting to identify live HIV-infected CD4 T cells.  The transcriptomes of these cells are then characterized using RNA seq. We have used these methods to characterize the transcriptomes from HIV-infected peripheral CD4 T cells and in ACH2 cells transitioning from “latent-infection” to “active-infection”. These studies have allowed us to correlate markers of disease progression such as CD4 down regulation, viral RNA concentrations and viral RNA splice patterns, with activation of NF-B pathway and increased HIV-RNA transcription.  We are currently using these methods to identify and characterize the longitudinal effect of SHIV infection on the CD4 T cell transcriptome of individual SHIV infected CD4 T cells from rhesus macaque lymph nodes.