Mechanisms of virus-induced immune suppression

The recent demonstration that the acquired immune deficiency syndrome (AIDS) is caused by a retrovirus that affects humans has given rise to widespread concern about the immunosuppressive properties of viruses in general. A wide variety of viruses have been shown to be able to compromise immune function. Sometimes immunosuppression results from the pathologic processes that viruses are able to induce. In other instances virus-induced immune derangements may themselves be responsible for the onset of pathologic change. In some cases a single infectious viral agent may be able to modulate several immunologic mechanisms simultaneously. This review discusses some of the various complex mechanisms through which viral infections can alter the function of the immune system.