Viral Infections and their Role in Autoimmune Diseases, with Emphasis on Mechanisms and Molecular Interactions

Introduction: The exact cause of most autoimmune diseases is still unknown; however, several factors play a role in causing or exacerbating autoimmune reactions. In addition to environmental factors such as bacterial, parasitic, fungal and viral infections, factors such as genetic characteristics and lifestyle are also included. Infections caused by viruses usually trigger a strong immune response that is essential to control the infection. However, in some cases, failure to regulate this immune response may lead to destructive immune reactions against host antigens. The present article discusses about mechanisms that viral infections and the path way that immune system responds to those infections. In addition, the present article review data related to ncidence of viral infections in development or exacerbation of autoimmune diseases. Methods and Materials: This review article has been performed by searching in international databases including PubMed, Scopus, and Google scholar as well as Persian databases such as SID and Magiran. Results: Epidemiological studies on humans as well as experimental studies on animals have shown that viral infections can cause autoimmune damage depending on various factors including genetic characteristics, host immune responses, type of virus strain, viral load, and time of onset of infection. They can induce or protect against its occurrence. However, limited data are available to describe the apparent interaction between the virus and the immune system to induce immune reactions. Discussion and Conclusion: Available data indicates that autoimmunity derived from viral infections can be activated through a number of mechanisms including molecular mimicry, epitope spreading, bystander activation, and immortalization of infected B cells. Protective effects can be achieved through overlooking autoimmune responses that were suppressed autoimmune events. Therefore, it is essential to have a better understanding of immune-related molecular processes in autoimmunity arises from viral infections.