TABLE 1.

Binding and VN activity of intact IgG and Faba

AssayEC50 (log10 M)Fab/IgG ratio
IgGFab
ELISA−9.52−9.281.7
VN activity
    MDCK−10.1−9.921.5
    Respiratory tract−9.51−9.221.9
  • a Dilutions of H36-4 IgG and Fab were tested in ELISA for binding to purified PR8 adsorbed to wells of polyvinyl plastic plates. Biotinylated MAb 187 (anti-Cκ) was used for detection of bound IgG and Fab. The mean EC50 values of two independent assays are shown. VN activity was measured in two types of assays. In both, virus-Ab mixtures were first incubated in vitro for 1 h and then inoculated either into MDCK cell microcultures (12 cultures per Ab dilution) or into the respiratory tracts of SCID mice under ketamine-xylazine anesthesia (three to four mice per Ab dilution). Three days later, MDCK cultures and SCID mice were tested for evidence of infection. In each case, the mean of two independent assays is shown.