Constantinos Petrovas, M.Sc., Ph.D.

Chief, Tissue Analysis Core

Major Areas of Interest

  • Development and application of novel imaging methods for analysis of tissue cells
  • T cell dynamics in secondary lymphoid organs in natural infection (HIV/SIV) and after vaccination
  • Generating “tissue imaging signatures” in cancer and cancer/HIV

Program Description

The mission of the Tissue Analysis Core is the development, optimization and application of cutting-edge imaging assays for the analysis of human and nonhuman primate (NHP) tissues in support of VRC goals. 

Imaging methodologies are a prerequisite for the understanding of:

  1. the spatial analysis of tissue immune cells and with respect to tissue structure
  2. the local interactions between immune cells, tissue stromal cells and tissue-expressed antigens (pathogens, cancer, self-antigens) 
  3. the role of local inflammatory mediators for the dynamics of tissue immune cells

A comprehensive tissue analysis requires the application of complementary technologies allowing for the characterization of phenotype, localization, function and molecular signatures of cells under investigation. Merging cutting-edge technologies like multidimensional imaging, multiparameter flow cytometry and deep sequencing allows for the generation of “imaging signatures” that could provide information about viral persistence in specific tissue areas-sanctuaries and assist in the discovery of biomarkers for disease progression and interventional strategies with specific immunotherapies and vaccines.

Current technologies employed in the Tissue Analysis Core include:    

  1. multispectral confocal imaging (A),
    Example of multispectral confocal imaging

    Example of multispectral confocal imaging 

    Credit: NIAID
  2. RNAscope methodology that allows for the simultaneous detection of mRNA and several protein markers (B),
    Example of RNAscope methodology that allows for the simultaneous detection of mRNA and several protein markers

    Example of RNAscope methodology

    Credit: NIAID
  3. live imaging and v) TIRF microscopy (C).
    Example of live imaging and TIRF microscopy

    Example of live imaging and TIRF microscopy

    Credit: NIAID

Several analytical tools (Imaris, Voloom, Histo-cytometry platform and in house developed algorithms) are used for the quantitative analysis of the obtained imaging objects.


 

Biography

Dr. Petrovas has been working in the field of HIV/SIV pathogenesis for more than 15 years. He obtained his Ph.D. in immunology studying anti-phospholipid antibodies in autoimmunity and HIV at the School of Medicine, National University of Athens, Greece. He pursued post-doctoral work at the Department of Biochemistry, Boston University and Department of Microbiology and Immunology, Drexel University before he joined the Immunology Laboratory at VRC in 2005. His previous work focused on the mechanisms mediating the “exhaustion” of SIV/HIV- specific CD8 T cells and he was the first to describe PD-1 as a mediator of SIV/HIV-specific CD8 T cell survival. More recently, his research has been focused on the dynamics of CD4 and CD8 T cells at tissue level and particularly in the lymph node follicles in HIV and SIV infection. His work was the first to describe the phenotype, localization, molecular profile and dynamics of Tfh CD4 T cells in acute and chronic SIV infection. Currently, he is characterizing the dynamics of tissue immune cells in HIV/SIV and cancer and developing tools to understand the interplay between inflammation, adaptive immunity and tissue antigens. 

Selected Publications

Eirini Moysi, Suresh Pallikkuth, Leslie R De Armas, Louis E Gonzalez, David Ambrozak, Varghese George, Rajendra Pahwa, David Huddleston, Richard A. Koup, Constantinos Petrovas and Savita Pahwa, “Multidimensional single cell imaging analysis reveals the impact of follicular dynamics in vaccine-specific B-cell responses in HIV cART donors”, Journal of Clinical Investigation (in press) (co-senior author).

S. Ferrando-Martinez, E. Moysi, A. Pegu, S. Andrews, D. Ambrozak, A.B. McDermott, M. Paiardini, G.N. Pavlakis, J Brenchley, J.R. Mascola, Constantinos Petrovas and R.A. Koup “Accumulation of follicular CD8+ T cells in pathogenic SIV infection”, Journal of Clinical Investigation, 2018 Apr 16. (co-senior author).

Jacob D. Estes, Roger LeGrand, Constantinos Petrovas, “Visualizing the Immune System: Providing Key Insights into HIV/SIV Infections”, Frontiers in Immunology, 2018 Mar 2;9:423.

Donato Amodio, Giulia Macchiarulo, Salvatore Rocca, Nicola Cotugno, Paolo Rossi, Richard Koup, Paolo Palma and Costantinos Petrovas, “Quantitative Multiplexed Imaging Analysis Reveals a Strong Association between Immunogen-Specific B Cell Responses and Tonsillar Germinal Center Immune Dynamics in Children after Influenza Vaccination.” Journal of Immunology, 2017 Dec 13.

Constantinos Petrovas, Sara Ferrando-Martinez, Michael Y Gerner, Joseph P Casazza, Amarendra Pegu, Arik Cooper, Jason Hataye, Sarah Andrews, David Ambrozak, Perla M Del Río Estrada, Eli Boritz, Robert Paris, Eirini Moysi, Kristin L Boswell, Ezequiel Ruiz-Mateos, Ilias Vagios, Manuel Leal, Yuria Ablanedo-Terrazas, Amaranta Rivero, Luz Alicia Gonzalez-Hernandez, Adrian B McDermott, Gustavo Reyes-Teran, Fernando Docobo, Giuseppe Pantaleo, Daniel C Douek, Michael R Betts, Ronald N Germain, John R Mascola and Richard A Koup “Follicular CD8 T cells accumulate in HIV infection and can kill infected cells in vitro via bispecific antibodies.” Science Translational Medicine, 2017 Jan 18;9(373).

 

 

 

 

Content last reviewed on May 7, 2018