TABLE 2.
50% neutralization titers of sera against homologous and heterologous virus strains
| Serum | Results, 50% neutralization capacitya
|
|||||||
|---|---|---|---|---|---|---|---|---|
| Homologous strain | Maximum | Minimum | Ratiob | Minimumc (−strain 244) | Ratioc | Ratio, (+/−C′) AD169d | Ratio, (+/−C′) 244d | |
| P1AN | 1:40,000 | 1:40,000 (P1AN) | 1:2,500 (244) | 16 | 1:6,400 (210) | 6.3 | 1.8 | 1.7 |
| 236 | 1:22,000 | 1:32,000 (236) | 1:2,400 (244) | 13.3 | 1:2,400 (210) | 13.3 | 1.5 | 1.8 |
| 210 | 1:12,800 | 1:13,000 (Towne) | 1:1,000 (244) | 13 | 1:9,000 (P143) | 1.4 | 1 | 1 |
| P143 | 1:3,000 | 1:3,200 (Towne) | 1:350 (244) | 9.1 | 1:1,200 (AD169) | 2.7 | ND | ND |
| R20 | 1:6,400 | 1:7,000 (236) | 1:600 (244) | 11.7 | 1:1,200 (AD169) | 5.8 | ND | ND |
| 244 | 1:300 | 1:3,500 (P143) | 1:300 (244) | 1.7 | 1:700 (AD169) | 5 | ND | ND |
| F3I | 1:1,300 | 1:1,300 (F3I) | 1:160 (244) | 8.1 | 1:350 (P1AN) | 3.7 | ND | ND |
| 209 | 1:380 | 1:1,000 (P143) | <1:50 (244/AD169) | >20 | <1:50 (AD169) | >20 | 1 | 4 |
| 252 | 1:2,500 | 1:3,000 (F3I) | <1:50 (244) | >60 | 1:150 (210) | 20 | ND | ND |
Neutralization was measured as described in Materials and Methods. The neutralization titer refers to the serum dilution, with the respective strain given in parentheses. ND, not determined.
Ratios were calculated according to the following formula: maximum neutralization capacity/minimum neutralization capacity.
Ratios were calculated according to the following formula: maximum neutralization capacity/minimum neutralization capacity without strain 244.
Neutralization assay was performed in the presence (+C′) or absence (−C′) of 2% human complement with strain AD169 or strain 244. The ratios were calculated according to the following formula: neutralization with complement/neutralization without complement.