Recombinant fowlpox virus elicits transient cytotoxic T cell responses due to suboptimal innate recognition and recruitment of T cell help

Copyright © 2008 Elsevier Ltd All rights reserved.Recombinant fowlpox viruses (FPVs) have been used in a variety of vaccine strategies; however strong data clearly demonstrating the characteristics of the strength and nature of the resultant immune response elicited by these vectors are lacking. By utilising a recombinant variant of FPV which expresses the nominal antigen chicken ovalbumin (OVA), and assessing innate FPV- and OVA-specific adaptive immune responses, we show that recombinant FPV induces a rapid type I interferon (IFN) response, mediated primarily by plasmacytoid dendritic cells (pDCs). These cells are necessary for the development of a strong but transient CD8(+) T cell effector response directed against OVA-expressing target cells. We propose that a combination of suboptimal type I IFN production, poor CD4(+) T cell helper function and inefficient DC licensing likely contribute to this transient response. These findings now provide a sound basis for rational modifications to be made to recombinant FPV, designed to improve subsequent vaccine responses.Kerrilyn R. Diener, Erin L. Lousberg, Emma L. Beukema, Anastasia Yu, Paul M. Howley, Michael P. Brown and John D. Hayballhttp://www.elsevier.com/wps/find/journaldescription.cws_home/30521/description#descriptio