Immunity to viruses

Abstract

The analysis of the innate and adaptive immune response to viruses has provided fundamental insight into the functioning of the immune system. Early studies on the host response to virus infection were instrumental in establishing the concept of immunological tolerance (1). Similarly, the realization that T lymphocytes are ‘restricted’ in their recognition of antigens by gene products encoded within the major histocompatibility complex (MHC) locus came from the analysis of T-lymphocyte recognition of virus-infected cells (2). Likewise, important initial insights into antigen processing and presentation came from the analysis of viruses and virus-infected cells (3, 4). Until recently, it was convenient to view immunity to infectious agents like viruses as a separate branch of immunology distinct from immunity to tumors, self-molecules (antigens), or allergens. As demonstrated in many of the articles in this volume of Immunological Reviews, the mechanisms underlying the induction and regulation of the innate and adaptive immune response to viruses represent the same processes controlling immunity to tumor antigens, allergens, and self-constituents. Thus, the results summarized in these review articles and the implications of these findings are applicable not only to those of us who study immunity to viruses but also to the immunology community at large. In selecting the topics for review in this volume of Immunological Reviews, we were first and foremost limited by space. Consequently, many important contributors to the field of viral immunology (indeed several topics) are not represented in this volume. Our selection of topics and authors was biased towards emerging areas, such as the application of systems biology approaches to viral pathogenesis and immunity, the contribution of inflammatory and stress responses to the induction of Innate and adaptive immune responses, and the impact of the microbiome on immunity to virus infection. We also considered it relevant to include reviews focused on well defined areas where recent findings have resulted in potential paradigm shifts in our understanding of topics such as B-lymphocyte or T-lymphocyte responses to virus infection. This volume of Immunological Reviews is also somewhat weighted towards analyses of the immune response to respiratory viruses. With the recent episodic infections with the severe acute respiratory syndrome (SARS)-like coronavirus and the outbreak of human infections with the avian influenza A H7N9 virus, respiratory viruses such as these organisms are recognized as major human pathogens with the potential for pandemic spread. Therefore, this class of viruses is a focus of immunological research. The reviews in this volume can be grouped according to the following scheme: (i) molecules and cells regulating the induction of the innate and adaptive response, (ii) expression of immune effector activity, (iii) regulation of the antiviral immune response, and (iv) systems analysis of the host response to infection and vaccination (Fig. 1). Fig. 1 Immunity to viruses