in order to gain insight into transmission and pathogenesis of infection , specimens from laying hens that had been naturally exposed to lymphoid leukosis virus ( llv ) were tested for group-specific antigen ( gsa ) of the virus by immunofluorescence ( if ) , complement fixation ( cf ) , and the enzyme-linked immunosorbant assay ( elisa ) .
C0017279
group-specific antigen
C0042776
virus