The V protein of the paramyxovirus simian virus 5 blocks interferon (IFN) signaling by targeting STAT1 for proteasome-mediated degradation. Here we report on the isolation of human cell lines that express the V protein and can no longer respond to IFN. A variety of viruses, particularly slow-growing wild-type viruses and vaccine candidate viruses (which are attenuated due to mutations that affect virus replication, virus spread, or ability to circumvent the IFN response), form bigger plaques and grow to titers that are increased as much as 10-to 4,000-fold in these IFN-nonresponsive cells. We discuss the practical applications of using such cells in vaccine development and manufacture, virus diagnostics and isolation of newly emerging viruses, and studies on host cell tropism and pathogenesis.
In vitro and in vivo specificity of ubiquitination and degradation of STAT1 and STAT2 by the V proteins of the paramyxoviruses simian virus 5 and human parainfluenza virus type 2 Previous work has documented that the V protein of simian virus 5 (SV5) targets STAT1 for proteasome-mediated degradation, whilst the V protein of human parainfluenza virus type 2 (hPIV2) targets STAT2. Here, it was shown that the processes of ubiquitination and degradation could be reconstructed in vitro by using programmed rabbit reticulocyte lysates. Using this system, the addition of bacterially expressed and purified SV5 V protein to programmed lysates was demonstrated to result in the polyubiquitination and degradation of in vitro-translated STAT1, but only if human STAT2 was also present. Surprisingly, in the same assay, purified hPIV2 V protein induced the polyubiquitination of both STAT1 and STAT2. In the light of these in vitro results, the specificity of degradation of STAT1 and STAT2 by SV5 and hPIV2 in tissue-culture cells was re-examined. As previously reported, STAT1 could not be detected in human cells that expressed SV5 V protein constitutively, whilst STAT2 could not be detected in human cells that expressed hPIV2 V protein, although the levels of STAT1 may also have been reduced in some human cells infected with hPIV2. In contrast, STAT1 could not be detected, whereas STAT2 remained present, in a variety of animal cells, including canine (MDCK) cells, that expressed the V protein of either SV5 or hPIV2. Thus, the V protein of SV5 appears to be highly specific for STAT1 degradation, but the V protein of hPIV2 is more promiscuous. well-established that SV5 and hPIV2, and many other paramyxoviruses, at least partially circumvent the IFN response by blocking IFN signalling and IFN production (reviewed by Garcia-Sastre, 2004;Horvath, 2004;Nagai & Kato, 2004). In human cells, SV5 and mumps virus block IFN signalling by targeting STAT1 for proteasomemediated degradation, whilst human hPIV2 targets STAT2 for degradation (Andrejeva et al., 2002b;Didcock et al., 1999a;Nishio et al., 2001;Parisien et al., 2001;Yokosawa et al., 2002;Young et al., 2000). As a consequence, SV5 inhibits both IFN-a/b and IFN-c signalling, whilst, in human cells, hPIV2 only blocks IFN-a/b signalling. Intriguingly, it has recently been reported that mumps virus, but not SV5, can also target STAT3 for degradation, although the biological significance of this has yet to be established (Ulane et al., 2003). The importance of IFN in controlling SV5 infections can be judged from studies in mice: SV5 fails to degrade STAT1 in murine cells and is non-pathogenic in normal and severe combined immunodeficient mice (which fail to make an adaptive immune response; Didcock et al., 1999b;Randall & Young, 1991) INTRODUCTION
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.