Viral Antigens

Viral antigens protrude from the capsid and often fulfill important function in docking to the host cell, fusion, and injection of viral DNA/RNA. Antibody-based immune responses form a first layer of protection of the host from viral infection; however, in many cases a vigorous cellular immune response mediated by T-cells and NK-cells is required for effective viral clearance. When cellular immunity is unable to clear the virus, the infection can become chronic, and serum antibodies to the viral pathogen are used as first indicator for the diagnosis of the disease.