TABLE 2.
Size and frequency of syncytia induced by HRSV F protein mutantsa
| HRSV strain | Sizeb | Frequencyc | Fusion indexd | Relative fusion index (%)e |
|---|---|---|---|---|
| Parental F | 8.7 | 0.39 | 3.4 | 100 |
| N27Q | 8.8 | 0.37 | 3.3 | 97 |
| N70Q | 9.4 | 0.51 | 4.8 | 141 |
| N116Q | 9.1 | 0.41 | 3.7 | 109 |
| N120Q | 8.0 | 0.33 | 2.6 | 76 |
| N126Q | 10.3 | 0.54 | 5.6 | 165 |
| N500Q | 4.3 | 0.10 | 0.4 | 12 |
| N500A | 4.6 | 0.11 | 0.5 | 15 |
| S502A | 4.6 | 0.12 | 0.6 | 17 |
| N27/70Q | 6.0 | 0.31 | 1.9 | 56 |
| N116/120Q | 8.9 | 0.44 | 3.9 | 115 |
| N27/500Q | 3.6 | 0.07 | 0.3 | 9 |
| N70/500Q | 4.1 | 0.09 | 0.4 | 12 |
| N27/70/500Q | 3.4 | 0.03 | 0.1 | 3 |
a
BSR-T7/5 cells transiently expressing parental or mutated HRSV F protein were analyzed by immunofluorescence (see Fig. 5). Results are mean values of data from three independently performed transfections.
b
The size of syncytia was determined by counting their nuclei.
c
The frequency of syncytium formation is the relation between the number of syncytia and the number of fluorescent cells.
d
The fusion index represents the product of syncytium size and syncitium frequency.
e
The relative fusion index was estimated by setting the fusion index of the parental F protein to 100%.