Understanding the Enigmatic Dance of Immune-Mediated Viral Infections and Their Pathogenetic Mechanisms

The immune system's response to viral infections can be both beneficial and dtrimental. The general immune response in a non-suppressed organism begins with the recognition of the infectious agent and its perception as non-self to the organism and works toward the termination of the viral infection. Conversely, the immune system may contribute to the pathogenicity of a viral infection via different responses. Cytokines, cell-mediated effector mechanisms and antibody-antigen complexes may cause immune-mediated viral disease. The resulting tissue damage was typically classified as four types of hypersensitivity reactions by Gell-Coombs. Notably, Type III (immune complex) and Type IV (cell-mediated) hypersensitivity responses are central in the pathophysiology of many viral diseases. Consequently, the host's defence against infection is more than a mere safeguard-in some cases, an overly vigorous immune response can cause pathology more severe than that induced by the virus itself. A thorough examination of the immune response to viruses also advances our understanding of autoimmune disease mechanisms, as viral infections can trigger autoimmunity through molecular mimicry and bystander activation. Understanding these pathogenic mechanisms is critical for managing the multisystemic consequences of viral diseases. This review focuses on the pathogenetic mechanisms of immune-mediated viral infections in animals.