Table 4.
Identification of critical residues of E2-specific mAbs binding by site-directed mutagenesis of CSFV and BDV E2 proteins a.
| Mutated Residue b | Strain c | mAbs against E2 | ||||||
|---|---|---|---|---|---|---|---|---|
| Domain B/C | Domain A | |||||||
| CSFV d | BDV | CSFV | ||||||
| 1C7A1 | 3C1E12 | WH220 | WH304 | WS381 | WS384 | WH303 | ||
| None | TD/96 | + | + | + | + | + | + | + |
| 94.4 | − | + | − | + | − | + | + | |
| LPC | − | − | + | + | − | − | + | |
| Moredun | − | + | − | − | + | + | − | |
| C693A | TD/96 | − | − | − | − | − | − | + |
| C737A | − | − | − | − | − | − | + | |
| P709G | TD/96 | + | + | + | + | − | − | + |
| P709L | TD/96 | + | + | + | + | − | ± | + |
| L709P | LPC | − | − | + | − | + | + | + |
| P709G | Moredun | − | + | − | − | − | − | − |
| P709L | Moredun | − | + | − | + | − | − | − |
| E713G | TD/96 | + | ± | + | + | + | ± | + |
| G713E | LPC | − | + | + | + | − | + | + |
| E713G | Moredun | − | ± | − | − | + | ± | − |
| G725D D725G |
TD/96 | − | + | + | + | + | + | + |
| LPC | + | − | + | + | − | − | + | |
| I738T T738V V738T |
TD/96 | + | + | − | + | + | + | + |
| 94.4 | − | + | + | + | − | + | + | |
| LPC | − | − | − | + | − | − | + | |
a Results were interpreted as positive (+), weak (±) or negative (−) in IFA. The grey highlights indicate mutations that result in a change in binding reactivity compared to the non-mutated E2. b Mutant E2 proteins are annotated according to the amino acid position of CSFV and the substitution introduced. Refer to Figure 3 for the selection of residues of interest to mutate. c TD/96, 94.4 and LPC indicated CSFV strain TD/96/TWN of genotype 2.1, 94.4/IL/94/TWN of genotype 3.4 and LPC/AHRI of genotype 1.1, respectively. Moredun indicated BDV Moredun strain of genotype 1.a. d Derived from CSFV or BDV.