How does your immune system recognize and fight viruses?

When a virus enters your body, your immune system responds in two main waves. The innate immune system acts first within hours, with cells like macrophages and natural killer cells detecting general signs of infection, such as viral proteins or unusual RNA patterns, and destroying infected cells while releasing signaling molecules called cytokines to trigger inflammation. The adaptive immune system then kicks in over days. B cells produce antibodies that bind specifically to viral surface proteins, neutralizing the virus and marking it for destruction. T cells play dual roles: helper T cells coordinate the immune response, while cytotoxic T cells directly kill infected cells. Crucially, memory B and T cells persist long-term, allowing faster, stronger responses if the same virus appears again.