Assertion: antigen's antibody | /r/AtLocation | the serum
Facets:
value: before viral infection
type: TEMPORAL
Source sentences:
text: If antibodies to HIV are present in the serum, they may bind to these HIV antigens.
text: Humans and higher primates also produce "natural antibodies" that are present in serum before viral infection.
text: -The higher the concentration of the primary antibody that was present in the serum, the stronger the colour change.