TABLE 1.
Biological activities of SPE C mutants
| Protein tested | Pyrogenicitya (Δ4h°C) | No. of rabbits surviving/total no. of animals
|
Half-maximum superantigen activity (μg/well)d | |
|---|---|---|---|---|
| Endotoxin enhancementb | Miniosmotic pump lethalityc | |||
| Wild type | Pyrogenic (1.67) | 0/6 | 0/6 | 10−8 |
| H167A | Pyrogenic (0.90) | 1/3 | 3/3 | 10−4 |
| H201A | Nonpyrogenic (0.30) | 3/3 | 3/3 | 10−2 |
| D203A | Nonpyrogenic (0.37) | 3/3 | 3/3 | 10−2 |
| H35A | Pyrogenic (0.73) | 0/3 | NDe | 10−5 |
| N38D | Nonpyrogenic (−0.30) | 3/3 | ND | 10−3 |
| Y15A | ND | ND | ND | >1 |
| N38D/D203A | ND | ND | ND | 10−2 |
| H167A/H201A/D203A | ND | ND | ND | >1 |
| Y15A/H167A/H201A/D203A | ND | ND | ND | >1 |
| Y15A/H35A/N38D | Nonpyrogenic (0.27) | 3/3 | ND | >1 |
Δ4h°C, average change in rabbit temperature (in degrees centigrade) at 4 h after intravenous injection.
Five micrograms of protein/kg/rabbit was given intravenously to each rabbit at time 0 followed by 10 μg of endotoxin/kg at 4 h. Animals were monitored for lethality for 2 days.
Five hundred micrograms of protein/kg/rabbit was administered via subcutaneous minosmotic pumps. Mortality was monitored for 15 days.
Rabbit splenocytes were incubated with protein in 96-well plates. After 3 days of incubation, 3H-labeled thymidine was added, and the plates were incubated an additional day. DNA was harvested, and radioactivity was measured. Half-maximum activity is reported as the quanity of protein required to give half the cpms of the most-active concentration of the same protein.
ND, not determined.