The phrase "viral antigens" refers to substances found on a virus that trigger the body's immune system. They can cause the body to produce antibodies, which help fight off the virus and prevent further infection. Full definition
The most commonly used vaccine against panleukopenia, herpesvirus and calicivirus is a multivalent vaccine: it contains viral antigens for several diseases together in the same dose, and is commonly abbreviated as the «FVRCP» vaccine. (cattime.com)
The ELISA (enzyme linked immunosorbent assay) test that detects viral antigen in fecal material is one of the most common tests shelters use. (animalsheltering.org)
Alpha Herpesviruses such as FHV - 1 cause disease by two distinctly different mechanisms: 1) cytolytic (cell - rupturing) disease which involves active viral replication and destroys the epithelial cells of the cornea and conjunctiva causing ulceration; and, 2) immune - mediated disease results from the deposition of viral antigen in subepithelial tissues. (eyespecialistsforanimals.com)