Event Title First Global Alliance for Research on Avian Diseases (GARAD) Conference
Session Title Unknown
Event Date & Time On Tue, 30 Jun 2015 at 10:45:00 - 11:20:00
Venue Edmond J. Safra Lecture Theatre
Abstract Title From basic immunology to application in infectious disease research
Authors Bernd Kaspers
Affiliations Institute for Animal Physiology, University of Munich, Germany
Abstract Content

Avian immunology has made considerable progress since the discovery of the function of the bursa of Fabricius and an additional boost came with the publication of the chicken genome sequence. However, at a functional level progress has been slow which is largely due to a lack of appropriate in vitro and in vivo techniques to investigate adaptive immune responses. In the past years, we have focused our attention on the chicken B-cell system to gain a better understanding of bursal B-cell development, post bursal B-cell maturation and the germinal center response. Through this work we identified a range of cytokines and chemokines critically involved in these biological processes. As a side effect, in vitro culture systems were established which finally allowed the maintenance and expansion of bursal and peripheral B-cells for extended periods of time. For the first time, these cultures enabled the in vitro infection of primary B-cells with the Marek’s Disease Virus (MDV) and the confirmation of the “Cornell model” of MDV pathogenesis. In addition, cultured primary B-cells can be infected efficiently with Infectious Bursal Disease Virus (IBDV) the second economically important pathogen with a high B-cell tropism. Both in vitro infection models now provide opportunities for in-depth studies on host-pathogen interaction with the natural target cells. In vitro infected cells can easily be sorted out and subjected to state of the art transcriptomic and proteomic analysis to gain insides into the host cell response and viral infection biology.

Studies aimed at understanding cytokine function in vivo led to the establishment of a simple and rapid overexpression system based on retrovirus mediated gene transfer into early chicken embryos. We applied the Rouse Sarcoma Virus based vector system RCAS to overexpress several B-cell cytokines and soluble decoy receptors as knock-down tools to define their role in chicken B-cell biology. In addition, we were able to apply this technology to investigate the role of the interferon system in highly pathogenic avian influenza virus infection. While RCAS mediated gene transfer is a straight forward approach, it comes with a number of drawbacks. The system does not lead to germ line transmission nor does it lead to gene overexpression in all somatic cells. From our experience it is suitable for research on soluble signaling molecules such as cytokines but inappropriate to study cellular protein function. Consequently, germ line modification of genes of interest would finally enable in vivo analysis of gene functions in the same way as demonstrated in the murine system over the past decades. Progress towards this technology came with primordial germ cell cultures and has led to the first true gene knock out bird having an immunoglobulin heavy chain knock out. These birds show interesting phenotypes in bursal B-cell development but completely lack peripheral B-cells and antibodies. They provide an easy system to gain insides into the role of the humoral immune response to infections and during vaccination as well as the importance of B-cells for highly B-cell tropic MDV and IBDV. We have now focused our interest on developing birds with αβ- and γδ-T-cell knockouts to finally get experimental access to T-cell mediated immune responses. Generating such birds on a syngeneic background would allow adoptive cell transfer experiments from e.g. immunized wild type birds into T-cell deficient animals which can subsequently be challenged by pathogens to dissect the role of T-cell subsets in vaccine induced immunity.