TABLE 1.
SIAa
| Conditions and TCLA strain | EC50 (μg/ml) of antibody and class
|
||||
|---|---|---|---|---|---|
| 2G12
|
2F5
|
||||
| IgG | IgM | IgG | IgM | IgA | |
| Standard | |||||
| MN | NT | NT | 0.16 | 0.4 | 2.4 |
| RF | 0.75 | 0.21 | NT | NT | NT |
| NL4-3 | 2.4 | 0.3 | 2.4 | 21 | >50 |
| Standard plus active human complement | |||||
| RF | 0.1 | 0.1 | NT | NT | NT |
| NL4-3 | 0.3 | 0.1 | 0.2 | 10.5 | >50 |
| Standard plus inactivated human plasma | |||||
| RF | 2.9 | 0.3 | NT | NT | NT |
| NL4-3 | 1.7 | 0.6 | 2.4 | 12.5 | >50 |
a
Effective antibody concentrations are listed as EC50s, representing the concentrations of antibody (micrograms per milliliter) causing 100% syncytium inhibition in 50% of the replicate wells. The assay was performed with the laboratory strains MN, RF, and NL4-3 (102 to 103 50% tissue culture infective doses/ml) and AA-2 cells. Normal human serum (diluted 1:8 to 1:16) was added as a source of active human complement in some experiments. Heat-inactivated human plasma was added as a negative control for complement activation in some experiments. The table summarizes the data of two independent assays. Lack of neutralization is indicated by an EC50 of >50 μg/ml. NT, not tested.