Table 2.
Titer and fusion ability of viral particles containing heterooligomers composed of two separate chimeric envelope proteins
| DNA | CEETR | D84KTR | 33E67TR | 33K67TR |
|---|---|---|---|---|
| CEE+ | +(7.0 × 106) | +(6.8 × 106) | +(3.5 × 106) | +(3.0 × 106) |
| D84K | +(5.3 ± 106) | −(0) | −(0) | −(0) |
| 33E67 | +(1.7 × 106) | −(0) | −(0) | −(0) |
| 33K67 | +(1.4 × 106) | −(0) | −(0) | −(0) |
To determine titer, supernatants from transfected cells were collected and added to 3T3/CD33 cells. After 10 days of selection in G418 (0.6 mg/ml), G418-resistant colonies were counted (data in parentheses). Except for CEE + (4 × 106) and CEETR (2.5 × 102), the titer of the supernatant from each of the other single DNA transfections is zero. Syncytia formation of 3T3/CD33 cells mediated by transfected envelope protein plasmid is indicated by a “+,” and no syncytia, by a “−.” Unless monomers of the wild-type (CEE+) or R-less wild-type (CEETR) envelope protein are present in the mixed heterooligomer, no syncytia formation occurs (see text).